JET Manual 38 version 2_1_4298920_01.pdf

JET Manual 38 WPS-BasicLaboratory Training and FluidQA/QCReference: InTouch content ID# 4298920Version: 2.1Release Date: 15-Oct-2014EDMS UID: 1656171227Produced: 15-Oct-2014 16:46:35Owner: WS Training & DevelopmentAuthor: Lisette Anabella Garcia Sanchez

Private PPCG, WS, SFE, JET Manual 38

Copyright 2014 Schlumberger, Unpublished Work. All rights reserved.

JET Manual 38 / Legal Information

Legal Information

Copyright 2014 Schlumberger, Unpublished Work. All rights reserved.

This work contains the confidential and proprietary trade secrets of Schlumbergerand may not be copied or stored in an information retrieval system, transferred,used, distributed, translated or retransmitted in any form or by any means,electronic or mechanical, in whole or in part, without the express writtenpermission of the copyright owner.

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Schlumberger, the Schlumberger logotype, and other words or symbols usedto identify the products and services described herein are either trademarks,trade names or service marks of Schlumberger and its licensors, or are theproperty of their respective owners. These marks may not be copied, imitatedor used, in whole or in part, without the express prior written permission ofSchlumberger. In addition, covers, page headers, custom graphics, icons, andother design elements may be service marks, trademarks, and/or trade dressof Schlumberger, and may not be copied, imitated, or used, in whole or in part,without the express prior written permission of Schlumberger.

A complete list of Schlumberger marks may be viewed at the SchlumbergerOilfield Services Marks page: http://markslist.slb.com

Marks of Schlumberger include but may not be limited to CLEAN SWEEP*,ClayACID*, ClearFRAC*, DAD*, DGA*, EB-Clean*, EZEFLO*, FracCADE*,GelSTREAK*, LCA*, MSR*, MaxCO3 Acid*, NARS*, OCA*, OilSEEKER*, PCM*,POD*, SDA*, SXE*, SuperX*, ThermaFRAC*, VDA*, YF GO*, YF*.

PrivateCopyright 2014 Schlumberger, Unpublished Work. All rights reserved.W

STraining&Development\LisetteAnabellaGarciaSanchez\InTouchcontentID#4298920\2.1\ReleaseDate:15-Oct-2014\EDMSUID:1656171227\Produced:15-Oct-201416:46:35

JET Manual 38 / Document Control

Document ControlOwner: WS Training & Development

Author: Lisette Anabella Garcia Sanchez

Reviewer: Samuel Danican, Sylvie Daniel; Olesya Levanyuk, Bruce MacKay, SalimTaoutaou

Approver: Fabricio Moretti, Steve Uren

Contact InformationName: WS Training & DevelopmentLDAP Alias: WS-PPC-TechCom

Revision HistoryVersion Date Description Prepared by

2.1 15-Oct-2014 Updated chemical name. Author: Daphne Chang(TechCom)

2.0 28-Aug-2012 Document updated as per ticket 5774619 andtransferred to EDMS.

Author: Lisette Anabella GarciaSanchez

1.0 05-Jun-2007 Initial release of the manual. Author: WS Training &Development



iv JET Manual 38 / Table of Contents iv

Table of Contents

Foreword ________________________________________________________ viii

1 Introduction ____________________________________________________ 1-11.1 Learning Objectives __________________________________________ 1-1

2 Safety Considerations __________________________________________ 2-12.1 Personal Protective Equipment _______________________________ 2-12.2 Emergency Equipment _______________________________________ 2-22.3 Chemical Spills ______________________________________________ 2-22.4 Key Service Quality Requirements (KSQR) ____________________ 2-3

3 Laboratory Truck and Technician _______________________________ 3-1

4 QA on Location ________________________________________________ 4-14.1 Water Tests __________________________________________________ 4-14.2 Gel Tests ____________________________________________________ 4-24.3 Other QA Tasks while Pumping _______________________________ 4-3

5 Typical Laboratory Tests _______________________________________ 5-15.1 Water Analysis _______________________________________________ 5-15.2 Linear Fluid Viscosity ________________________________________ 5-135.3 Vortex Closure ______________________________________________ 5-145.4 Fracturing Fluid Crosslink Delay _____________________________ 5-165.5 Static Gel Break Test ________________________________________ 5-185.6 HPHT Gel Rheology Tests ___________________________________ 5-205.7 Fracturing Sand Sieve Analysis ______________________________ 5-225.8 Proppant Turbidity Test ______________________________________ 5-255.9 Silt Turbidity Test ____________________________________________ 5-265.10 Proppant Sphericity and Roundness Test _____________________ 5-275.11 Fluid Compatibility with Resin-Coated Proppants (RCP) Test ___ 5-285.12 Vapor Pressure Test _________________________________________ 5-29

6 Hydraulic Fracturing Fluids ____________________________________ 6-16.1 Preparing Linear Gel Fluids ___________________________________ 6-16.2 Preparing YF100HTD Fluids __________________________________ 6-26.3 Preparing YF100FlexD Fluids _________________________________ 6-46.4 Preparing YF800HT Fluids ___________________________________ 6-66.5 Preparing YF100LG Fluids ___________________________________ 6-86.6 Preparing YF100LGD Fluids _________________________________ 6-106.7 Determining Crosslink Delay Time ___________________________ 6-12



v JET Manual 38 / Table of Contents v

6.8 Preparing ThermaFRAC Fluids ______________________________ 6-126.9 Preparing YF GO V Fluids ___________________________________ 6-156.10 Preparing SuperX Emulsion (SXE) ___________________________ 6-176.11 Preparing ClearFRAC XT Fluids _____________________________ 6-18

7 Preparing Matrix Acidizing Fluids ______________________________ 7-17.1 Preparing Hydrochloric Acid (HCl) _____________________________ 7-17.2 Mixing Intensified Acid _______________________________________ 7-27.3 Mixing ClayACID _____________________________________________ 7-37.4 Mixing Mud Acid _____________________________________________ 7-57.5 Mixing Organic Mud Acid _____________________________________ 7-77.6 Preparing Organic ClayACID _________________________________ 7-87.7 Preparing Alcoholic Acid ______________________________________ 7-97.8 Mixing Dynamic Acid Dispersion (DAD) ________________________ 7-9

8 Quality Assurance/Quality Control (QA/QC) Practices __________ 8-18.1 Fracture Fluid QA/QC ________________________________________ 8-18.2 Acidizing fluid QA/QC ________________________________________ 8-38.3 Fluid Additives QA/QC _______________________________________ 8-4

9 References _____________________________________________________ 9-1

10 Check Your Understanding ____________________________________ 10-1



vi JET Manual 38 / List of Figures vi

List of Figures

2-1 Key Service Quality Requirements for Fracturing ____________________ 2-42-2 Key Service Quality Requirements for Matrix Acidizing _______________ 2-53-1 Field Laboratory Truck _____________________________________________ 3-13-2 Field Quality Assurance/Quality Control (QA/QC) Kit _________________ 3-23-3 Laboratory Technician Hard at Work ________________________________ 3-35-1 HACH DR/2000 Spectrophotometer with Two Sample Cells __________ 5-55-2 High-Pressure, High-Temperature (HPHT) Viscometers _____________ 5-205-3 ASTM Standard Sieves and Sieve Shaker__________________________ 5-235-4 Sphericity Versus Roundness _____________________________________ 5-276-1 Sample Linear Gel_________________________________________________ 6-16-2 Sample Crosslinked Gel ___________________________________________ 6-4



vii JET Manual 38 / List of Tables vii

List of Tables

5-1 Alkalinity Indicators ________________________________________________ 5-75-2 Specific Gravity (SG) of Fluid Versus Amount of Sample _____________ 5-75-3 Recommended Sieve Sizes for Fracturing Sands ___________________ 5-246-1 Quantities of J511 in YF100 LGD __________________________________ 6-116-2 J518 and Activator for YF GO V gel________________________________ 6-167-1 Acid Systems Most used by Schlumberger __________________________ 7-17-2 Dilutions of Concentrated Hydrochloric acid _________________________ 7-27-3 Formulations for ClayACIDs ________________________________________ 7-57-4 Formulations for Low-Temperature ClayACIDs_______________________ 7-57-5 Mud Acid Formulations_____________________________________________ 7-67-6 OCA Formulations_________________________________________________ 7-87-7 Conditions for Using OCA Formulations _____________________________ 7-8



viii JET Manual 38 / List of Tables viii

Intentionally Blank



i JET Manual 38 / Foreword i

Foreword Well Services, PPCG, PPC, forewordNew releases of this document supersede any other version. The most currentversion of the document is in www.InTouchSupport.com.

If you have a printed copy, check the "Release Date" against the content inInTouch to be sure you have the most current version.

This document is OBSOLETE when printed.



1-i JET Manual 38 / Introduction 1-i

1 Introduction

1.1 Learning Objectives ____________________________________________ 1-1



1-1 JET Manual 38 / Introduction 1-1

1 IntroductionPPCG, WS, SFE, JET Manual 38

Stimulation treatments restore or enhance the productivity of a well. Fracturingtreatments occur above the fracture pressure of the reservoir formation to createa highly conductive flow path between the reservoir and the wellbore. Matrixtreatments occur below the reservoir fracture pressure to restore the naturalpermeability of the reservoir following damage to the near-wellbore area. Thestimulation fluid is a critical component of the stimulation treatment. In fracturing,the fracturing fluid function is to open the fracture and to transport propping agentalong the length of the fracture. In matrix stimulation, the main acid function is toetch the formation, creating highly conductive paths (wormholes), or removingdamage. To ensure the fluid, proppant and acid pumped are of the best qualityand to maintain the quality during the treatment, the laboratory technician mustperform a variety of tests. This module introduces basic field and laboratory teststhat employees performing the fluid tests should know.

1.1 Learning ObjectivesThe objective of this manual is to introduce you to Well Productivity Services(WPS) basic laboratory training and fluid quality assurance/quality control(QA/QC). After reading this manual, you should be able to do the following:

Perform water analyses.

Understand Fann Model 35 viscometer operation and perform gel viscositymeasurement.

Understand the vortex closure test.

Perform the fracturing fluid crosslink delay test.

Perform the static gel break test.

Understand Fann Model 50-type viscometer operation and perform an HPHTgel rheology test.

Perform sand sieve analysis.

Prepare hydraulic fracturing fluids.

Prepare matrix acidizing fluids.

Understand fracturing fluids QA/QC.



1-2 JET Manual 38 / Introduction 1-2

NoteAlthough the Fann brand is stated here, Chandler (3500 or 5550) or Grace(M5600) instruments may also be used. Refer to specific Chandler or Graceinstrument manual for operating details.



2-i JET Manual 38 / Safety Considerations 2-i

2 Safety Considerations

2.1 Personal Protective Equipment _________________________________ 2-12.2 Emergency Equipment _________________________________________ 2-22.3 Chemical Spills ________________________________________________ 2-22.4 Key Service Quality Requirements (KSQR) _____________________ 2-3



2-1 JET Manual 38 / Safety Considerations 2-1

2 Safety ConsiderationsPPCG, WS, SFE, JET Manual 38

All employees working in a stimulation laboratory must follow specific rules andprocedures to prevent injuries and loss of equipment.

All Well Services (WS) and Oilfield Services (OFS) safety standards must becomplied with. All personnel must comply with WS QHSE Std 24: LaboratoryOperations, InTouch content ID# 3313702.

2.1 Personal Protective EquipmentProper personal protective equipment (PPE) should be worn while working inthe laboratory.

Eye protection Safety glasses with fixed side shields are required at all times as minimumeye protection (this requirement does not apply to offices, restrooms, orother protected areas not in the laboratory working area).

Indirect vented chemical goggles must be worn when handling chemicalssuch as cement, unless these chemicals are in sealed containers.

Face shields must be worn when handling hot liquids, acids, or liquidsthat are under pressure, or working with flammable liquids where theflash point is less than 100 degF [38 degC].

Visitors must wear safety glasses with side shields and laboratory coatswhile in the laboratory work areas.

Protective clothing Laboratory coats with long sleeves must be worn as the minimumprotective clothing.

Rubber or plastic protective aprons must be worn, depending on thetype of chemical. Read the material safety data sheet (MSDS) for eachchemical for the protective clothing requirements.

Types of clothing that allow exposure to a large area of skin must not beworn in a laboratory (e.g., sleeveless tops, short skirts, or short pants).




Other requirements Safety boots are not required in the laboratory. Shoes that provideprotection from liquids must be worn, such as a leather shoe that coversthe foot. Sandals and open shoes are not permitted.

Gloves must be worn when handling chemicals, according to the MSDS.

Refer to SLB QHSE Standard S003 (Personal Protective Equipment), InTouchcontent ID# 3260259, for more information.

2.2 Emergency EquipmentEvery WS laboratory must have the following emergency equipment available:

at least one eyewash station and one emergency shower

fire extinguishers that are easily accessible in case of fire

a complete first aid kit

fire blankets available in any laboratory where tests are performed withflammable liquids

Chemical spill control kits; the kits must include rubber gloves, absorbentmaterial or spill booms, disposal bags or containers with labels.

easy access to exits so that personnel can leave the laboratory in case ofa fire

emergency numbers and procedures displayed at the entrance to thelaboratory.

2.3 Chemical SpillsThe following lists the precautions that must be taken for chemical spills.

Each laboratory and laboratory field van must be equipped with the spilldisposal kit.




A spill response plan should be prepared that follows this general outline: Make sure all personnel are removed from the area.

If flammable or combustible fluids are used, shut off or remove allpossible sources of ignition.

Stop the chemical discharge.

Apply absorbent material to control all free liquids and place any mate-rial into a disposal container found in the spill disposal kit.

Add a label to the disposal container that shows the contents and date.

Place the container with other chemicals ready for disposal.

Report the spill to the health, safety, and environment (HSE)representative.

Chemicals must not be put into a sink drain or any drain that is connected toa sewer or waste water drainage system.

All drain pipes must comply with local regulations. The contents of all drainsmust be analyzed every 12 months. The data must be recorded and kept onfile.

The Schlumberger mercury-free policy prohibits mercury anywhere in thelaboratories; this includes a prohibition of mercury thermometers.

2.4 Key Service Quality Requirements (KSQR)The Well Services - Key Service Quality Requirements (KSQR), InTouch contentID# 4147783, detail the steps that must be taken to ensure that fracturing (Figure2-1) and matrix acidizing (Figure 2-2) jobs are performed right the first time. It iscrucial to follow these requirements for successful job preparation and execution.

Additionally, base fluid laboratory testing and proppant testing must be donefor ALL jobs as per Key Service Quality Testing Requirements (Fluids andProppant), InTouch content ID# 3051128.

KSQRs are periodically reviewed and updated. Refer to the respective InTouchpages for the latest KSQRs. The job must be pumped as designed. Anydeviation from original job procedure requires that SLB QHSE Standard S010(MOC and Exemptions), InTouch content ID# 3260269, and SLB QHSE S010,WS Appendix: Exemptions, InTouch content ID# 3999148 be followed.




Figure 2-1: Key Service Quality Requirements for Fracturing




Figure 2-2: Key Service Quality Requirements for Matrix Acidizing



3-i JET Manual 38 / Laboratory Truck and Technician 3-i

3 Laboratory Truck and Technician



3-1 JET Manual 38 / Laboratory Truck and Technician 3-1

3 Laboratory Truck and TechnicianPPCG, WS, SFE, JET Manual 38

A laboratory truck (Figure 3-1) or similar dedicated laboratory unit, equippedwith basic fluid quality testing tools (Figure 3-2) must be present at the job siteduring a fracture treatment.

Figure 3-1: Field Laboratory Truck




A

B C

D

F

G

HI

JKL

M

N

Field QA/QC kit

E

Figure 3-2: Field Quality Assurance/Quality Control (QA/QC) Kit

Key: A: Mud balance

B: Water bath

C: Balance

D: Digital titrator

E: Retort kit

F: Hydrometers, graduated cylinders, syringes, flasks, beakers, samplebottles

G: Stopwatch

H: Process controlled rheometer

I: Variable speed mixer

J: Emulsion stability meter

K: Conductivity meter, remote laser thermometer, dry probe pH meter

L: Bacteria luminometer

M: Reagents

N: Production screen tester




Fluid samples gathered from the field blending equipment, or frac tanks if batchmixed, are checked for quality control. On land-based fracture treatments, thefluid is most often mixed in a PCM* (precision continuous mixer) and suppliedto a POD* (programmable optimum density) blender. The QA that can beperformed with this truck in the field laboratory ensures that the treatment isexecuted as designed. Simple QA steps can greatly increase the odds ofsuccess for a hydraulic fracturing treatment.

The laboratory technician (Figure 3-3):

works under the direction of the job supervisor to collect samples and performfluid quality control

must understand the principles of stimulation and fluid rheology

must be able to calculate and prepare solution concentrations and additives

checks the quality of the water before gel is prepared

collects samples for testing and troubleshoots all problems of hydration,gel loading or crosslinking.

Figure 3-3: Laboratory Technician Hard at Work



4-i JET Manual 38 / QA on Location 4-i

4 QA on Location

4.1 Water Tests ____________________________________________________ 4-14.1.1 Iron Concentration Test _______________________________________ 4-14.1.2 Bicarbonate Concentration ___________________________________ 4-24.2 Gel Tests _______________________________________________________ 4-24.3 Other QA Tasks while Pumping ________________________________ 4-3



4-1 JET Manual 38 / QA on Location 4-1

4 QA on LocationPPCG, WS, SFE, JET Manual 38

The following are quality assurance (QA) tasks that must be performed onlocation before pumping the stimulation treatment.

4.1 Water Tests

NoteLaboratory personnel must ensure that reagents, buffers, and chemicals are indate, and that all pH meters must be calibrated before use.

Tests must be performed on the mix water for:

temperature

pH

specific gravity (SG)

iron concentration

bicarbonate concentration.

You will need a sample of water from each tank (3 to 5 L). At least 1 L ofwater should be reserved in case additional testing is necessary in the districtlaboratory after the fracture, such as in the case of a screenout.

Test the water parameters to ensure that they are within the range of acceptablevalues for the fluid pumped.

4.1.1 Iron Concentration TestPerform this test using a HACH iron test kit as follows:

1. Insert the iron color disk into the comparator.

2. Fill a clean color test tube to the 5-mL mark, add the chemical packet to thetube and shake to mix. An orange color will develop if iron is present.

3. Insert the tube of prepared sample into the right top opening of thecomparator.




4. Fill the other color viewing tube with an untreated water sample. Place it inthe left top opening of the color comparator.

5. Hold the comparator up to a light source and view through the openingsin front. Rotate the disc to obtain a color match. Read the mg/L iron (Fe)concentration through the scale window.

6. If the concentration is greater than 10 mg/L, perform another test with adiluted sample as follows:

a. Use a 1-mL sample of water to be tested and 4 mL of distilled ordeionized (DI) water.

b. Follow the procedure in Steps 1 through 5, but multiply the results by 5.

4.1.2 Bicarbonate ConcentrationTo test for bicarbonate concentrations:

1. Measure 100 mL of undiluted sample into a 300-mL glass beaker.

2. Insert a clean delivery tube into the titration cartridge (1.6N H2SO4). Attachthe cartridge to the titrator body.

3. Hold the digital titrator with the cartridge tip pointing down. Turn the deliveryknob to eject air and a few drops of titrant.

4. Reset the counter to zero and wipe the tip.

5. Add the contents of one Bromocresol green-methyl red indicator powderpacket to the glass beaker and swirl to mix.

6. Titrate with sulfuric acid to a light pink color. As the titration progresses, thecolors will change from light greenish blue-gray to light pink.

7. Record the value shown on the digital titrator as the total bicarbonate (theunits are in mg/L as CaCO3).

4.2 Gel TestsThe linear gel must be tested before beginning the job. A linear gel sampleprepared with the actual water and chemical samples on location must be mixedand analyzed before job fluid mixing commences. Use the procedure detailed inSection 6.1: Preparing Linear Gel Fluids, to check the viscosity of the gel usingthe Fann 35-type viscometer and compare the tested viscosity and temperaturewith the expected ranges. When this sample meets the specification, begin initialmixing with the PCM or GelSTREAK* and perform the following tests.

1. Measure the pH of the linear gel and record it.




2. Divide the linear gel into two beakers of 250 mL each.

3. Make a crosslinked solution using the volumes recommended in laboratorytesting procedure. Ensure you check the specific gravity and pH of activatorand specific gravity of the breaker sample.

4. Start the mixer at a low speed and add the chemicals.

5. Measure and record the time it takes for the fluid to have a vortex closure inthe mixer and the time it takes for the fluid to have a good hang lip (crosslink).

6. Test and record the pH of the crosslinked fluid.

7. For borate fluid systems only: Perform a shear test of the fluid bysubmitting it to high speeds in the mixer and ensuring that the fluid will healitself after shear.

8. Perform a breaker test at bottomhole temperature (BHT). Use concentrationsdictated by the latest laboratory report to add the correct amount of breaker toa beaker of crosslinked gel. Place the sample into a water bath at bottomholetemperature. Test and record the time until the gel starts to break.

4.3 Other QA Tasks while PumpingThe following are common QA tasks while pumping:

Throughout the job, linear gel should be continually checked for viscosity toconfirm the proper gel loading.

Samples should be taken from the outlet of the blender or fracture pumps totest the delay time of the crosslinked fluid as well as pH, temperature, BHTstability, and break testing (water bath).

The physical quantities of all liquid and dry additives should be continuallychecked throughout the job and compared to the designed amount to bepumped.



5-i JET Manual 38 / Typical Laboratory Tests 5-i

5 Typical Laboratory Tests

5.1 Water Analysis _________________________________________________ 5-15.1.1 Testing pH, Specific Gravity, and Turbidity _____________________ 5-2

5.1.1.1 Testing pH _______________________________________________ 5-25.1.1.2 Testing Specific Gravity ___________________________________ 5-35.1.1.3 Testing Turbidity __________________________________________ 5-45.1.2 Testing Alkalinity (Indicator Method) ___________________________ 5-65.1.3 Testing Chloride _____________________________________________ 5-75.1.4 Testing Calcium and Magnesium ______________________________ 5-8

5.1.4.1 Testing Calcium __________________________________________ 5-85.1.4.2 Testing Magnesium _______________________________________ 5-95.1.5 Testing Sulphate, Barium, Iron, and Potassium ________________ 5-10

5.1.5.1 Testing Iron (HACH Method) _____________________________ 5-115.1.6 Testing Sodium (Calculation Method) _________________________ 5-125.2 Linear Fluid Viscosity _________________________________________ 5-13

5.2.1 Determining Water-Base Fluid Linear Gel Viscosity ____________ 5-135.3 Vortex Closure ________________________________________________ 5-145.4 Fracturing Fluid Crosslink Delay ______________________________ 5-165.5 Static Gel Break Test __________________________________________ 5-185.6 HPHT Gel Rheology Tests _____________________________________ 5-205.7 Fracturing Sand Sieve Analysis _______________________________ 5-22

5.7.1 Sampling Techniques _______________________________________ 5-235.7.2 Sand Sieve Analysis (Modified API Method) __________________ 5-245.8 Proppant Turbidity Test _______________________________________ 5-255.9 Silt Turbidity Test ______________________________________________ 5-265.10 Proppant Sphericity and Roundness Test _____________________ 5-275.11 Fluid Compatibility with Resin-Coated Proppants (RCP) Test __ 5-285.12 Vapor Pressure Test ___________________________________________ 5-29



5-1 JET Manual 38 / Typical Laboratory Tests 5-1

5 Typical Laboratory TestsPPCG, WS, SFE, JET Manual 38

Several tests are commonly performed at the district laboratory before the job.For details and procedures on the required tests for each type of stimulationjob, refer to Stimulation District Lab Procedures, InTouch content ID# 5563263,and Key Service Quality Testing Requirements (Fluids and Proppant), InTouchcontent ID# 3051128.

Typical laboratory tests include:

Water analysis

Linear fluid viscosity

Vortex closure

Fracturing fluid crosslink delay

Static gel break test

HPHT gel rheology

Fracturing sand sieve analysis

Proppant turbidity test

Silt turbidity test

Proppant sphericity and roundness

Fluid compatibility with resin-coated proppants (RCP)

Vapor pressure test

5.1 Water AnalysisThe oil industry uses water analysis for quality control, formation identification,compatibility studies, and environmental evaluations.

The following procedures have been developed to perform the necessary wateranalyses.

pH testing (meter) and temperature

specific gravity (SG) testing (hydrometer and SG bottle method)

turbidity testing (HACH method)




total dissolved solids (TDS) (by gravimetric analysis)

ion concentrations (e.g., chlorides, calcium, magnesium, sulfate, iron,etc.)

5.1.1 Testing pH, Specific Gravity, and TurbidityYou will need the following items to test water for pH, specific gravity, andturbidity:

pH meter and calibration solutions

SG bottle

balance

filtering apparatus and accessories (filter paper, vacuum pump and funnelassembly).

5.1.1.1 Testing pH

The normal pH range for brines is between 6 to 8. A low pH may indicate spentacid, whereas a high pH may indicate contamination by mud, filtrate or bacteria.Some of the constituents that control the pH of water are dissolved solids,precipitation of iron, carbon dioxide, bicarbonate, borate, and hydrogen sulfide.The pH of water can strongly affect the hydration of a polymer and mechanismof some crosslinking reactions. It should be tested using pH paper and morepreferably a digital pH meter.

pH paper is appropriate for a quick check on most fluids, providing the paper isnot beyond its shelf life and has not been exposed to extreme heat or sunlight.The pH paper test procedure is very simple:

1. Dip a piece of pH paper into the water sample.

2. Match the color of the paper with the chart on the package of pH paper.

For a more accurate reading, a pH meter should be used:

1. Calibrate the pH meter as described in the pH meter manual.

2. Shake the water sample to homogenize it.

3. Insert the pH probe into the water sample.

4. Read the pH on the meter screen after the reading stabilizes. Check thetemperature. Record the pH and temperature.




Note The closer the pH is to 8.0, the slower the gel will hydrate.

If the pH is close to or equal to 8.0, it is recommended to buffer with acid.

If the pH is above 8.0, the water must be buffered.

If buffering the tank, add 1 galUS 36% HCl per 20,000 galUS and checkthe pH. If the pH is at or above 7.5, add HCl by the quart until the pHis below 7.5.

5.1.1.2 Testing Specific Gravity

Specific gravity is the ratio of the weight of material to the weight of water, or thedensity of the material to the density of water. Freshwater has a specific gravityof 1.000. The higher the specific gravity, the heavier the liquid will be. Specificgravity can be used to differentiate hydrocarbons (condensate) from water. Ahydrometer is used to measure specific gravity.

There are two different procedures that can be performed to test water forspecific gravity: the hydrometer procedure and the SG bottle procedure.

Hydrometer procedure (the preferred method in the field):

1. Fill a graduated cylinder with the fluid to be tested. Use a 100-mL cylinder fora 7-in hydrometer and 250-mL cylinder for a 12-in hydrometer.

2. Carefully drop the hydrometer into the liquid with a slight spin.

3. Read the value for specific gravity where the top of the fluid intersects one ofthe lines on the hydrometer.

4. The value for specific gravity should be corrected for temperature by usingthe temperature correction table (rule of thumb: Add 0.0002 to the SG forevery degree above 60 degF).

HCl strength can also be determined from its specific gravity and comparedto the chart in the acid strength chart found in the Field Data Handbook.

Use this equation to relate API (American Petroleum Institute) gravity tospecific gravity:

=+

SG API

141.5131.5

=AP1 SGSG

141.5 131.5 ( )




NoteThe higher the API gravity, the lighter the fluid.

SG Bottle procedure:

To determine the SG using the SG bottle:

NoteClean everything you used for this test with deionized (DI) water.

1. Weigh the empty SG bottle and record the weight as W1.

2. Fill the bottle with DI water until water runs out of the capillary and cap it.

3. Weigh the bottle containing DI water and record the weight as W2.

4. Clean the bottle to be used for the water sample three times, fill it with thewater sample, and cap it.

5. Weigh the bottle containing the water sample and record the weight as W3.

Calculate the SG of the sample water from the formula:

=

SG W WW W

3 12 1

5.1.1.3 Testing Turbidity

Make sure you use unfiltered water for this test. To test water for turbidity:

1. Switch on the HACH DR/2000 spectrophotometer (Figure 5-1) and enter themethod number 750.




Figure 5-1: HACH DR/2000 Spectrophotometer with Two Sample Cells

2. Adjust the wavelength to 450 nm for this test.

3. Fill a clean sample cell with 25 mL of the water sample and another cleansample cell with 25 mL of DI water.

4. Insert the DI water sample cell into the cell holder and close the shield.

5. Press ZERO to zero the machine.

6. Place the sample cell with the sample water into the holder and close theshield.

7. Press READ/ENTER to obtain the FTU water turbidity.

8. Turn off the HACH DR/2000 and clean up the cells with DI water.




5.1.2 Testing Alkalinity (Indicator Method)Fluids should be tested for alkalinity; bicarbonates, carbonates, and hydroxidecan all increase alkalinity.

Bicarbonate measurement is very important for fracture fluid quality control.Fracturing fluids require various bicarbonate concentrations depending on thespecific fluid. High bicarbonate concentrations will tend to slow gel hydration anddelay fluid crosslink. If high bicarbonate concentrations are encountered, the fluidmay be treated with calcium chloride (S001), which will react with bicarbonateion. Calcium carbonate will precipitate, thereby reducing the dissolvedbicarbonate concentration. The precipitate will not interfere with the fluid.

The other reason to determine the bicarbonate concentration is to identify thewater source. High bicarbonate concentrations may be characterized by a highpH or be an indication of carbonates present in the water.

Most formations do not contain carbonates or hydroxides. If a water samplecontains carbonates and/or hydroxide, it may be a clue to a problem inthe customers well, possibly indicating the presence of some drilling mudcontamination.

To test the alkalinity, use a 50-mL sample regardless of the specific gravity. Then:

1. Add 3 drops of phenolphthalein indicator. If the sample did not turn pink, thesample does not contain carbonates or hydroxide. Continue with Step 2.

If the sample did turn pink, continue to Step 5.

2. If the sample did not turn pink, add dropper of methyl purple.

3. Titrate with 0.1N HCl or 0.0164 N HCl to the purple endpoint.

4. Calculate the bicarbonate concentration:

For 0.1N HCl, bicarbonate (mg/L) = mL of 0.1N HCl x 122

For 0.0164N HCl, bicarbonate (mg/L) = mL of 0.0164N HCl x 20

NoteThese equations are valid only for 50-mL samples.

5. If the sample did turn pink after Step 1, titrate with 0.1 N HCl until the pinkcolor disappears. The amount of 0.1N HCl used will be P in the calculations.

6. Add 3 drops of methyl purple.




7. If the sample turns green, titrate with 0.1 N HCl to the purple endpoint. Thetotal amount of 0.1 N HCl used in both titrations will be T in the calculations.

8. Perform the calculations indicated in Table 5-1.

Table 5-1: Alkalinity Indicators

Indicator Bicarbonate Carbonate Hydroxide

P 1/2P None 2(T-P) 2P-T

P = T None None T

where:

P = amount of 0.1 N HCl required to titrate sample to a colorless endpointafter adding phenolphthaleinT = amount of 0.1 N HCl required to titrate samples to a colorless endpointafter adding phenolphthalein plus the amount of 0.1 N HCl required to titratesample to the purple endpoint after adding of methyl purple

bicarbonate (mg/L) = mL of 0.1N HCl x 122

carbonates (mg/L) = mL of 0.1N HCl x 60

hydroxides (mg/L) = mL of 0.1N HCl x 34.

5.1.3 Testing ChlorideThe chloride test is generally used to determine if the sample is formation fluid ortreatment fluid. Fracturing fluids today can contain 2% KCl. The chloride contentof a 2% potassium chloride solution should be approximately 9,600 mg/L.

The chloride test can also be used to determine if a sample is spent acid.The characteristics of spent acid are a high chloride content and a pH ofapproximately 3.0 to 6.0.

1. Check SG to determine the proper sample size according to Table 5-2.

Table 5-2: Specific Gravity (SG) of Fluid Versus Amount of Sample

Specific Gravity Amount of Sample, mL

1.000 to 1.003 50

1.003 to 1.020 10

1.020 and over 1

2. Dilute sample to 50 mL with distilled or DI water.




3. Add 3 to 4 drops of potassium chromate.

4. Titrate to the orange/red endpoint with 0.1N silver nitrate.

NoteIf a sample contains H2S (it will have a rotten egg smell), heat the samplein a fume cupboard until the odor is eliminated.

5. Perform the following calculation:

=Cl mg L ( / ) x mL of silver nitratesample size mL

3, 545 ( )

For concentrations of silver nitrate other than 0.1N, use this calculation:

=Cl mg L ( / ) mL of silver nitrate x normality of silver nitrate xsample size mL

35, 500 ( )

5.1.4 Testing Calcium and MagnesiumThe following sections describe how to determine the calcium and magnesiumcontent in the water. Magnesium and calcium are the most common sourcesof hardness in produced waters; any other components that may contribute tototal hardness are negligible.

5.1.4.1 Testing Calcium

Most produced water will have less than 15,000 mg/L of calcium. If higherconcentrations of calcium are encountered, the water is almost certainly from alimestone or dolomite formation that has recently been acidized. If you suspectyou might have an acid sample, check the chlorides and compare it to values intthe table on chloride discussion. If less than 15,000 mg/L calcium is detected,continue the water analysis.

To determine the calcium content:

1. Determine the correct sample size. The sample size depends on the SG ofthe fluid (refer to Table 5-2).

2. Dilute the sample (if less than 50 mL) to 50 mL with distilled water.

3. Add 3 to 4 drops NH4OH.

4. Add 2 scoops of Calver II hardness reagent.




5. Titrate with 0.025 M EDTA (ethylenediamine tetraacetic acid) to the blueendpoint.

6. Perform the following calculations:

=Ca Mg L ( / ) mL of M EDTA used xsample size mL

0.025 1, 000 ( )

For EDTA concentrations other than 0.025 M, use this equation:

=Ca Mg L ( / ) mL of EDTA x Molarity of EDTA xsample size mL

40, 100 ( )

5.1.4.2 Testing Magnesium

The magnesium test used (standard titration method) is a test for total hardness.

This test assumes that the water hardness is due to dissolved magnesium andcalcium only. Generally, the magnesium concentration is used for total dissolvedsolids (TDS) calculations to identify the water source. However, high magnesiumis generally due to a recent acid treatment of a dolomite formation.

The following standard titration method requires that calcium be determinedbefore calculating the magnesium concentration. Subtract the calciumconcentration from the total hardness and assume the remaining hardness isdue to magnesium.

Follow this procedure.

1. Determine the correct sample size.

2. Dilute to 50 mL with distilled water.

3. Add 3 to 4 drops NH4OH.

4. Add 2 scoops of Univer II hardness reagent.

5. Titrate with 0.025 M EDTA to the blue endpoint.

NoteThis test is for the total hardness. To find the amount of 0.025 M EDTA formagnesium, subtract the number of mL of 0.025 M EDTA used to determinecalcium. This difference is the number of mL of 0.025 M EDTA used todetermine the magnesium.

6. Perform the following calculation:




=Mg mg L ( / ) mL of M EDTA for Mg mL EDTA for Ca x

sample size mL(( 0.025 ) ( )) 606

( )

For EDTA concentrations other than 0.025 M, use this equation:

=Mg mg L ( / ) mL of M EDTA for Mg mL EDTA for Ca x M of EDTA x

sample size mL(( 0.025 ) ( )) 24, 340

( )

5.1.5 Testing Sulphate, Barium, Iron, and PotassiumTo test the quantity of sulfate, barium, iron, and potassium in the sample usingthe HACH DR/2000 spectrophotometer, you will need the following items:

HACH DR/2000 with accessories

DI water

SulfaVer Reagent Powder Pillow for SO42-

BariVer 4 Reagent Powder Pillow for Ba2+

FeroVer Iron Reagent Powder Pillow for Fe2+/Fe3+

potassium I/II/III reagent, for K+

water sample.

Follow this procedure.

1. Switch on the HACH DR/2000. Repeat Steps 2 through 14 for eachcontaminant being tested for.

2. Enter the appropriate stored program number (680 for sulphate, 20 forbarium, 265 for iron, and 950 for potassium).

3. Rotate the wavelength dial until the display shows 450 nm for sulphate orbarium, 510 nm for iron, or 650 nm for potassium.

4. Press READ/ENTER.

5. Pour 25 mL of sample into the sample cell.

6. Add the contents of appropriate reagent powder pillow to the sample cell (theprepared sample). Swirl to dissolve.

7. Press SHIFT TIMER.

8. When the timer beeps, fill another sample cell (blank) to 25 mL of samplewith DI water. Place it into the cell holder and close the light shield.

9. Press ZERO to zero the machine.




10. Within a few minutes after the timer beeps, place the prepared sample intothe cell holder. Close the light shield.

11. Press READ/ENTER.

12. Record the reading.

13. Dilute the sample if the reading flashes (over limit) and repeat the aboveprocedures.

To determine the quantity of the contaminant, use the following equation.

Contaminant content (mg/L) = HACH DR/2000 reading dilution factor (ifany)

5.1.5.1 Testing Iron (HACH Method)

When high iron is encountered in fracture fluid mix water, Breaker J218(ammonium persulfate) will have an accelerated effect. In high iron environments,J218 may cause premature breaking of the fracture fluid.

In addition, high iron content will interfere with the crosslinking of the fracturefluid, resulting in poor crosslink integrity.

The maximum iron concentration for fracturing water ranges from 8 to 25 mg/L,depending on the fluid.

During acid treatments ferric iron (Fe3+) is the major concern. When ferric ironreaches approximately 2,000 ppm in the acid system and is not 100% reduced,emulsion or sludging may be encountered. Commonly total iron is considered tobe a ratio of 3:1 or 5:1 ferrous to ferric iron.

The dissolved iron concentration may need to be determined after an acid jobor be monitored during pickling of tubulars. In those cases much higher ironconcentration would be expected. Monitoring iron concentration in returnedspend acid and returned pickling acid will aid Schlumberger and the customer indetermined adequate iron control for future acid treatments.

If pH is between 1 and 7 test the sample with an iron strip to determine ageneral range of iron concentration.

If iron concentration is zero ppm this test is sufficient.

If iron concentration is above approximately 10 ppm (10 mg/L) but below 25ppm (25 mg/L), use the HACH Color Comparator Kit No 187.

You will need a CHEMetrics kit if pH is below 1.0.

Follow this procedure to determine the iron content.




1. Fill the dilutor snapper cup to the 25 mL mark with iron-free water.

2. Fill the microtest tube halfway with your sample.

3. Holding the VACUette almost horizontally, touch the tip to the contents of themicrotest tube. The tip fills completely by capillary action.

4. Completely immerse the VACUette tip into the contents of the dilutor snappercup. Snap the tip of the ampule and wait until the VACUette fills up. Thesample fills the ampoule and begins to mix with the reagent.

NoteA small bubble of inert gas will remain in the ampoule to facilitate mixing.

5. Remove the VACUette from the dilutor snapper cup. Mix the contents of theVACUette by inverting it several times, allowing the bubble to travel fromend to end each time.

6. After 1 minute, use the appropriate comparator to determine the level ofiron in the sample.

5.1.6 Testing Sodium (Calculation Method)To determine the sodium content of the water using the results of the testsdescribed in Sections 5.1.1 through 5.1.5, use this equation:

mg/L of Na+ = 23 (A/35.5 + B/61 + C/60 + D/17 E/56 F/137 G/24 H/40I/39)

where:

A = chloride (mg/L)B = bicarbonate (mg/L)C = mg/L of carbonate (mg/L)D = mg/L of hydroxyls (mg/L)E = mg/L of iron (mg/L)F = mg/L of barium (mg/L)G = mg/L of Magnesium (mg/L)H = mg/L of calcium (mg/L)I = mg/L of potassium (mg/L).




5.2 Linear Fluid ViscosityTo determine the viscosity of linear fluids (including water-based fracturingfluids, gelled oils, and gelled acids), the Fann Model 35 rheometer (Fann 35)is primarily used.

Follow these practices to calibrate the rheometer:

Perform a full calibration the Monday of each week or each 75 hours ofoperation, whichever comes first.

The rheometer must be cool and clean.

The rheometer must agree with the calibration oil chart to within 1 cP (1mPas).

If the rheometer does not calibrate, then service the unit or send out for repairas instructed by the instrument manual.

After each test, do the following: Take off rotor and bob. Clean each piece with soap and water.

Wipe off the shaft with a damp cloth in a down motion. Do not pressagainst the shaft-up motion pushes fluid up the shaft.

Reassemble unit ensuring that each piece is finger tight. Tightening thebob or the rotor too much can damage the shaft and torque transducer.

5.2.1 Determining Water-Base Fluid Linear Gel ViscosityTo determine water-base fluid linear gel viscosity, you will need the followingitems:

Fann 35 viscometer with appropriate parameters (speed factor, R-B factorand spring factor)

rotor and bob

Fann 35 sample cup

fracturing fluid

thermometer

water sample.




The approach is to hydrate the polymer following the procedures in the FracturingMaterials Manual Volume I, Volume II and Volume III: Fluids, InTouch contentID# 4223817, sample the fluid, load the fluid into the Model 35 sample cup, andrecord the bob deflection at different rotor rotational speeds. Generally 6 rpmsare available: 3, 6, 100, 200, 300, 600 rpm.

1. Power on the Fann 35.

2. Install the rotor and bob if they are not in there already.

3. Fill the sample cup to the mark with fracturing fluid.

4. Place the sample cup on the stage. The three pins on the bottom of thecup sit in three holes on the stage.

5. Raise the stage until the sample cup is at the mark on the rotor.

6. Set the Fann 35 to the desired shear rate.

NoteShift gears only when the instrument is running.

7. Let the dial come to a steady reading and record the reading.

8. Measure and record the fluid temperature.

9. Compare the reading with the appropriate hydration curve. All laboratoriesand laboratory trucks should have the hydration curves onsite; you can alsofind them in the Fracturing Materials Manual Volume I, Volume II and VolumeIII: Fluids, InTouch content ID# 4223817.

Allow the gel to hydrate for an additional 10 minutes if the viscosity is95% of the nominal value.

Verify that the pH and water temperature are within the prescribed limits.

Add polymer in 2-lbm/1,000 galUS increments if the viscosity is still lowafter 10 additional minutes of hydration and the pH and water temperatureare within specification.

5.3 Vortex ClosureVortex closure is one method for estimating a crosslink time, as are the crosslinkdelay temperature and crosslink delay time tests. But, whereas the crosslinkdelay temperature or crosslink delay time tests indicate the time or temperaturerequired to achieve a lipping fluid, the vortex closure test simply indicates theonset of viscosity development (and rarely coincides with full crosslinking).

There are three distinct fluid behaviors during a vortex closure test:




1. The first is the linear fluid behavior. This is the initial state of the fluid andis characterized by a deep vortex.

2. The second is the viscosity increase that results in vortex closure, but doesnot stop fluid circulation in the blender cup.

3. The third behavior is fluid crowning, which is the formation of a dome of fluidover the center of the blender cup (over the blades). This is the point atwhich the fluid no longer completely circulates in the blender cup. It indicatescrosslinking has occurred and an elastic lipping material has formed.

It is important to determine the time to both vortex closure and fluid crowningduring a vortex closure test.

NoteContinuing to shear the fluid after vortex closure will degrade the thermal stabilityand appearance of the gel. Therefore, you must prepare a new fluid samplefor breaker tests or for baseline fluid performance characterization; do not usethe same fluid sample from which the vortex closure and crowning times aredetermined.

You will need the following items to perform the vortex closure test:

Waring blender

timer

fluid to be tested, including all additives

crosslinker to be tested.

To perform the vortex closure test:

1. Prepare 250 mL of the base fluid (KCl or L064, surfactants, stabilizers, andbuffers for polymer fluids; the fracturing oil and the recommended additivesfor gelled oils). Include all additives except the crosslinker.

2. Add the base fluid to a 1-L glass Waring blender cup. Adjust the mixingspeed to develop a deep vortex. The top of the blade nut should just bevisible, but the flats of the blade should be covered in the fluid.

3. Simultaneously add the crosslinker/activator package and start a timer.

4. Record the time at which the vortex closes. At vortex closure, the fluid willstill be circulating in the blender and will appear to fold away from the blendersides into the center of the cup. There may still be a depression in the fluidsurface at the center of the cup, but the vortex that remains is very little.




5. Continue mixing the fluid. Record the time at which the fluid surface stopsmoving and forms a small dome at the center of the blender cup. This timeis the crowning time.

5.4 Fracturing Fluid Crosslink DelayCrosslinking is a chemical reaction allowing a continuous, three-dimensionalstructure to form in a fluid under the right conditions. Crosslinking reactions aredelayed to reduce friction pressure during pumping and to reduce the time acrosslinked fluid is exposed to high shear rates. Most metal-crosslinked polymerfluids are irreversibly destroyed when they are exposed to high shear rates aftercrosslinking.

The delay between adding the crosslinkers and the actual crosslinking isthe crosslink delay time. Any factor that affects the dissolution rate (such astemperature, concentration, shear rate, particle size distribution) will change thecrosslink delay. Typically, fluids that use dissolving particles are time delayed.

It is also possible to add additives that affect the interaction between thecrosslinker and the polymer until the fluid temperature increases. Thetemperature at which crosslinking will occur is called the crosslinking delaytemperature.

You will need the following items to test the crosslinking delay and thecrosslinking delay temperature:

Waring blender

4 plastic cups

glass beaker

pH meter

thermometer

timer

fluid sample.

There are numerous ways to determine the crosslink delay time and crosslinkdelay temperature of hydraulic fracturing fluids. Unfortunately, the mostcommonly employed methods are highly subjective. This JET manual outlinesthe basic procedures used for these subjective tests.




NoteBe careful to follow this procedure exactly. Subtle differences in the initialconditions and the mixing steps will change the results.

Sample preparation

You will repeat the following steps to prepare samples for the crosslink delay timeand the crosslink delay temperature tests.

1. Prepare 250 mL of the fracturing fluid following the procedure given in therelevant section of the Fracturing Materials Manual.

NoteDo not add the last ingredient (typically the crosslinker and/or buffer) untilthe initial fluid temperature and pH are measured.

2. Measure and record the fluid temperature and pH.

3. Add the last ingredient, the crosslinker and/or buffer, to the fracturing fluidand mix in the Waring blender at 2,000 rpm for 30 seconds. The crosslinkdelay time measurement starts as soon as the last ingredients are added tothe fluid; record this time. Measure the final fluid pH during this step.

Crosslink delay temperature

Follow this procedure to determine the crosslink delay temperature.

1. Transfer the entire contents of the blender cup into a glass beaker. Place thebeaker into a microwave oven and heat the fluid for 10 seconds.

2. Remove the cup and briefly stir the fluid with a thermometer at a rate similarto whipping eggs with a whisk. Then, allow the thermometer to equilibratewith the fluid and record the temperature. Take 15 seconds or less for thismixing and temperature measurement step.

3. Repeat Steps 1 and 2 as necessary. Record the temperature at which thefollowing three characteristics are evident.

a. Initially, the fluid begins to thicken. It may remain linear or it may becomestringy and cling to the thermometer. However it manifests this stage, thefluid is now substantially more viscous than the linear gel was. Somecall the temperature at which this point is reached the initial crosslinktemperature.




b. The fluid can support a pencil-thick tongue hanging off the edge of thebeaker. The temperature at which it is possible to pull the tongue backinto the beaker is the crosslink temperature. This is the temperaturethat should be used for designing the crosslink delay temperature forthe treatments.

c. The fluid eventually becomes dry (usually) and can support a broad, thicktongue hanging off the edge of the beaker. The temperature at whichthis occurs is the full dry crosslink.

5.5 Static Gel Break TestThe static gel break test determines the time at which the gel breaks enoughto flow back. A gel is usually considered broken enough to flow back when ithas degraded to a viscosity of 20 cP (20 mPas) at the required temperature.This test is important for the field operation that does not have high-pressure,high-temperature (HPHT), gel break test equipment.

You will need the following items to perform the static gel break test for anytemperature:

1,000 mL jar with cap

200-mL high temperature bottles

HPHT fluid-loss cell and heating jacket

Fann 35 rheometer with proper accessories

water bath with temperature control

thermometer

stopwatch

gel and breaker sample.

Follow this test procedure for temperatures less than 100 degF [38 degC].

1. Prepare the base gel.

2. Place the required amount of breaker solution into the linear gel beforeadding the crosslinker solution. Dissolve J218 or J481 into a small amountof water; use equivalent amounts of J218 and J481 if J475 and J490encapsulated breaker are used and refer to FMM Vol III - Section 4: Breakersand Breaker Aids, InTouch content ID# 4879459, for the encapsulatedbreaker release rate.

3. Crosslink the gel according to fluid preparation procedures that are publishedfor that particular gel.




4. Preheat the water bath to the required temperature.

5. Pour 500 mL of gel into the jar. Replace the cap.

6. Place the jar containing the gel in the water bath to bring the sample tothe required temperature. Stir it slowly while heating, to accelerate thecrosslinking process. Start the timer when the temperature reaches theindicated bottomhole temperature (BHT).

7. Tighten the cap. Shake the jar vigorously every 30 minutes and visuallyobserve the viscosity.

8. Install the Fann 35s rotor, bob, and sample cup. Heat the sample cup.

9. Take enough of the gel from the jar to fill the sample cup and place it into theheated sample cup.

10. Place the thermometer into the sample. Watch the thermometer closely.Start testing the fluid viscosity at 170 s-1 as quickly as possible when the fluidtemperature is at the required temperature (the BHT). The Fann 35 doesnot have heating capabilities, so the sample should be heated to BHT inthe water bath.

11. Continue the process in Step 3 until fluid viscosity reaches 20 cP (20mPas). Record the time required to reach this viscosity, which is the staticgel break time.

Follow this test procedure for temperatures greater than 100 degF [38 degC],using a HPHT fluid-loss cell.

1. Prepare the base gel.

2. Place the required amount of breaker solution into the linear gel before addingthe crosslinker solution. Dissolve J218 or J481 into a small amount of water;use equivalent amount of J218 and J481 if J475 and J490 encapsulatedbreaker are used, and refer to FMM Vol III - Section 4: Breakers and BreakerAids, InTouch content ID# 4879459, for encapsulated breaker release rate.

3. Crosslink the gel according to the fluid preparation procedures.

4. Preheat the heating jacket to the required bottomhole static temperature(BHST).

5. Place the crosslinked gel into the bottle and finger tighten the cap. Put thebottle with the sample into the HPHT cell containing the proper level of oiljust below the bottle cap connection, to avoid oil getting into the bottle andcontaminating the fluid. Keep the whole cell assembly vertical while puttingthe bottle into the HPHT cell.

6. Place the HPHT cell assembly with bottle/oil heating medium into the heatingjacket; again, keep all components vertical.

7. Start the timer when the HPHT cell temperature reaches the indicated BHT.




8. Visually observe the viscosity of the fluid by cooling down the cell andtaking out the bottle at the expected breaking time. Using your laboratoryexperience, determine whether it has broken or not. If it does not break,repeat the test with more breaker.

5.6 HPHT Gel Rheology TestsThe following breaker tests are to be completed to generate or verify anappropriate breaker schedule and verify fluid stability at temperature.

1. Control fluid (fluid without breaker) at PAD stage BHT.

2. PAD fluid (with breaker, when applicable) at PAD stage BHT.

3. Additional stage testing (different stages/breaker loadings/BHTs) sufficient tosuccessfully generate or verify a breaker schedule.

A Fann Model 50-type viscometer is used for performing a crosslinked gelbreaking test when a BHT above 100 degF [38 degC] is required (refer to Figure5-2).

Figure 5-2: High-Pressure, High-Temperature (HPHT) Viscometers. Left toright: Fann 50, Chandler 5500 and Grace M5600

You will need the following items to perform this test:

High-pressure, high-temperature (HPHT) viscometer, e.g., Fann Model50-type viscometer with appropriate parameters (speed factor, R-B factor,and spring factor).

Rotor and bob 5 or bob 5X; different bobs will have different shear rateramps. For example, shear rate ramp corresponds to 118 rpm, 88 rpm, 59rpm, 88 rpm, and 118 rpm with a B5 bob.




fracturing fluid sample.

To perform the HPHT gel rheology tests:

NoteThese steps could vary with different types of viscometers.

1. Power on the viscometer and its computer.

2. Supply water and nitrogen (N2) (usually at 450 psi (3,105 kPa) (or 800 psi(5,520 kPa) for encapsulated breakers)) after the machine is calibratedproperly.

3. Prepare the crosslinked fracturing fluid as described in the specific fracturingfluid laboratory preparation procedures.

4. Activate the viscometer computer program and select Operating Menu, thenHeat Bath. Type in the required temperature to start preheating the oil bath.

5. Place about 26 mL (for a bob 5) of the crosslinked gel inside the rotor cup,followed by the required amount of breaker.

6. Place approximately 26 mL more of the crosslinked gel into the rotor cup.

7. Screw the bob counterclockwise to the shaft until it is finger tight.

8. Slowly screw the rotor containing the sample to the expansion fitting untilit is finger tight.

9. Take off the cover of the oil bath and close the glass door.

10. Go to the Operating Menu, and then Custom (or API). The API ramp shouldbe one of the following:

118 rpm (100 s-1)

88.5 rpm (75 s-1)

59 rpm (50 s-1)

29.5 rpm (25 s-1)

59 rpm (50 s-1)

88.5 rpm (75 s-1)

118 rpm (100 s-1)

11. Choose bob 5, interval stir rate (118 rpm), and final temperature set point.

12. Click Initial test in the operating menu followed by Yes and OK to go to ASCIIFILE and report printout. Choose the options you need.




13. Follow the screens through until Perform Test appears; click it. (Theinstrument will automatically run until the program finishes and prints out theresults. If you want to stop the machine during testing, go to the operatingmenu and select Shut down.)

14. Click the file on the top of screen and find the Reprint report. Click it toprint out the report manually.

15. Allow the machine to cool down below 100 degF [38 degC]. Release thepressure and close the water line.

16. Disassemble the rotor cup and bob gently and clean them up using therecommended cleaner.

17. Turn on the nitrogen to 10 to 20 psi (69 to 138 kPa) to get all excess wateror gel residue out of the expansion fitting.

18. Spray some WD40 on the shaft to lubricate the bearing. Use a paper towelto wipe the moisture and gel off the shaft very gently (do not press againstthe shaft). Clean everything used and cover the oil bath.

19. Turn off the machine and release the pressure in the main nitrogen line.

5.7 Fracturing Sand Sieve AnalysisThe sand used as a proppant must be analyzed for size of the grains. You willuse a series of sieves that are stacked in a specified order; refer to Figure 5-3.




Figure 5-3: ASTM Standard Sieves and Sieve Shaker

5.7.1 Sampling TechniquesA proper sampling ensures that a representative sample of the fracturing sandis obtained for quality control testing.

Delivery samples

Nine samples per railroad car and three samples per truck load areneeded, and five samples per 100,000 lbm (45,359 kg) when on location.

When the proper number of samples are obtained, combine the samplesfor one test.

Conveyor belt samples

Sand falling from a conveyor belt into a truck or railcar should be allowedto flow for at least 2 minutes before catching sample; wait 2 minutes afterthe start of each compartment when catching location samples.




Place the sampling device in the stream of sand with its longitudinal axisperpendicular to the flowing sand. Move the sampling box at a uniformrate from side to side in the sand stream. Several samples should beextracted at uniform intervals through the body of sand and combinedfor a representative sample.

Alternate sampling method (non-API)

If a flowing sample is not possible or desired, then a grain thief may beused to obtain a sample. It is recommended to catch at least three sampleswhenever possible and combine them for testing.

5.7.2 Sand Sieve Analysis (Modified API Method)This method has been modified to meet specific criteria requested by clients.This method exceeds the API recommended practice for sand sieve analysis.

1. Refer to ISO 13503-2 (Petroleum and natural gas industries Completionfluids and materials Part 2: Measurement of properties of proppants used inhydraulic fracturing and gravel-packing operations) or Table 5-3 to determinethe recommended sieve sizes used in testing designated sand sizes.

Table 5-3: Recommended Sieve Sizes for Fracturing Sands

Fracturing Sand Size Designations

USA Sieves Recommended

6/12 8/16 12/20 16/30 20/40 30/50 40/70 70/140

4 6 8 12 16 20 30 50

6 8 12 16 20 30 40 70

8 12 16 20 30 40 50 100

10 14 18 25 35 45 60 120

12 16 20 30 40 50 70 140

16 20 30 40 50 70 100 200

Pan Pan Pan Pan Pan Pan Pan Pan

2. Establish an accurate weight (WT) of the 100 g split sample to within 0.1 g.

3. Make sure that all sieves are completely cleaned with themanufacturer-recommended brush. Weigh each sieve accurately and recordthe weights.

4. Stack the sieves in order of increasing mesh size from bottom to top, withthe pan on the bottom.




5. Pour the sample onto the top sieve and place the sieve set plus the pan inthe test sieve shaker. Cover the sieves and tighten the sieve set.

6. Power on the sieve shaker for 10 minutes.

7. Remove each sieve and weigh each sieve separately with its contents.Weigh the pan as well.

NoteRemember to brush off the particles from the bottom of each sieve into thenext size sieve before weighing either.

8. Calculate the percent by weight of the total sand sample retained on eachsieve and the pan. To calculate the percentage by weight of the sand fallingwithin the designated sieve sizes, use these equations:

weight of the retained sand (WR) = sieve weight after shaking sieveweight before shaking

wt % of the total sand sample retained on each sieve = WR/WT x 100.

9. For fracturing proppants, a minimum of 90 wt % of the tested proppantsample (96.0% for gravel packing) shall be pass the coarse designed sieveand be retained on the fine designated sieve. Not over 0.1% of the totaltested proppant sample shall be larger than the first sieve size in the nestspecified in Table 5-3 and not over 1.0% of the total tested proppant sampleshall be smaller than the last designated sieve size.

NoteThe cumulative weight should be within 0.5% of the sample weight used inthe test; if not, the sieve analysis must be repeated using a different sample.

5.8 Proppant Turbidity TestThe turbidity test is performed to determine the cleanliness of the fracture sand(amount of fines present).

You will need the following equipment and materials to perform the proppantturbidity test:

sand sample

distilled or DI water

glass medicine bottle graduated to 100 mL with cap

black felt tip permanent marker




small funnel to pour sand into medicine bottle.

To perform the proppant turbidity test:

1. Mark the flat side of the bottle with an X using the black felt tip marker.

2. Fill the bottle to the 20-mL mark with sand.

3. Add distilled water to the 100-mL mark and secure cap.

4. Shake the bottle vigorously for 20 seconds.

5. In a well-lit area, hold the bottle at arms length with the flat side away fromyou. If the X can be seen clearly, the sand passes the turbidity test. If the X isbarely distinguishable or cannot be seen, the sand fails the test.

NoteAfter the turbidity test is complete, check the pH of the sample; if the pH isabove 6.0, the sand will be acceptable for YF*100 and YF200 series fluids.

5.9 Silt Turbidity TestTurbidity in water is the result of suspended clay, silt, or finely divided inorganicmatter being present. The HACH DR/2000 spectrometer measures the opticalproperty of the suspension, providing a turbidity value for the tested proppantsample. The turbidity of the tested proppant sample should be 250 (FTU)formazine turbidity units or less.

You will need the following items to perform the silt turbidity test:

HACH DR/2000-type spectrometer

sample vials

6-oz or larger, plastic-capped, wide-mouth bottle

syringe/pipette

DI water

proppant sample.

To perform the silt turbidity test:

1. Measure 20 mL of dry proppant sample and 100 mL of DI water in a 6-ozwide-mouth bottle, mix well, and allow to stand for 30 minutes.

2. Shake the bottle vigorously by hand for 45 to 60 shakes in 30 seconds. Allowit to stand for 5 minutes.




3. Switch on the spectrometer.

4. Dial the method number 750 and set the wavelength to 450 nm.

5. Zero the FTU using DI water in the test vial.

6. Using a syringe or pipette, extract 25 mL of water-silt suspension from nearthe center of the water volume.

7. Place the water-silt suspension in the test vial.

8. Determine the sample turbidity in FTU and record.

5.10 Proppant Sphericity and Roundness TestParticle sphericity is a measurement of how closely a sand particle or grainapproaches the shape of a sphere. Grain roundness is a measure of the relativesharpness of grain corners, or of grain curvature. Figure 5-4 illustrates theseconcepts.

The test method is specified by ISO 13503-2 (Krumbein and Sloss visualestimation method).

Figure 5-4: Sphericity Versus Roundness

You will need the following equipment to test for sphericity and roundness:




optical microscope Heerbrugg, Model Wild M3 or scanning electronmicroscope (SEM), Phillips, Model XL30

sample sticker/platform

proppant sample.

To test for sphericity and roundness:

1. Stick 20 or more grains of proppant on the glass plate platform for electronicscanning electron microscope (ESEM).

2. Switch on the optical microscope. Refer to the SEM analysis for ESEMstartup procedures.

3. Adjust the magnification until a clear picture of proppant particles appears.

4. Compare the shape of the particles visually with the standard chart (refer toISO 13503-2) and determine the sphericity and roundness of each particle.

5. Record the average of the above reading as the sphericity of the proppantsample.

5.11 Fluid Compatibility with Resin-CoatedProppants (RCP) TestLaboratory testing is performed to determine the compatibility of RCP withfracturing fluids.

You will need the following items to test the fluid's compatibility with the RCP:

pH meter

water bath

Waring blender

linear gel sample

all additives

RCP sample

fluid not exposed to RCP.

To test the fluids compatibility with the RCP:

1. Prepare 500 mL of linear gel plus all additives except crosslinker. Thecrosslinker is not added for zirconate crosslinked fluids to prevent sheardegradation during compatibility test.




2. Measure pH using the pH meter.

3. Add 10 ppa (lbm of proppant added) of RCP, and mix for 30 seconds at amixer speed that creates a vortex without significantly entraining air.

4. Place the mixture in a water bath at 150 degF [66 degC] for 30 minutes.

5. After 30 minutes, remove the mixture from the bath and mix for 30 secondsmore. Stop blender and allow proppant to settle to bottom of container.

NoteAllow fluid to cool before continuing.

6. Transfer 250 mL of fluid (without proppant) into a clean blender.

7. Measure pH using the pH meter.

8. Add crosslinker and perform the benchtop and rheology tests describedhere, or use the Fracturing Materials Manual. Follow the relevant qualitycontrol standard procedures.

9. Compare fluid properties and rheology profile with that of a fluid not exposedto RCP. Viscosities measured on a Fann 50-type rheometer should be similarfor fluids prepared with and without RCP exposure (typically within 100 cP(100 mPas) for same test conditions).

10. If a loss in viscosity is observed, fluid performance may be improved byincreasing the crosslinker concentration.

However, if significant loss in viscosity is observedthe fluid is not stable andlooks brokenthen that fluid is not compatible with that RCP.

5.12 Vapor Pressure TestThe Reid method is used to determine the vapor pressure of petroleum products.This method offers the type of data commonly requested for the field.

NoteWarning:

Keep heat and ignition sources away from the test.

You will need the following items to perform the vapor pressure test:

sample to be tested




NoteSample should be handled carefully to minimize vapor loss.

water bath, adjustable from 100 to 140 degF [38 to 60 degC]

For details on the Reid vapor pressure tester, refer to ASTM232-82.

To perform the vapor pressure test:

1. Unscrew the testing chamber at its midsection and inspect the O-ring seal.

2. Transfer 25 to 30 mL of sample to the bottom half of the testing chamber andthen quickly screw the upper and lower halves together.

3. Immerse the apparatus into the water bath and start heating. Heat bathslowly so that the sample temperature remains close to the bath temperature.

4. Using the Reid vapor pressure tester, record the vapor pressure of thesample when the temperature is 100 degF [38 degC]. Note the exacttemperature and pressure when taking a reading. Be sure to shake the testchamber vigorously before each reading to ensure that the validity of thesample has been maximized.

5. Continue heating and record the vapor pressure when the bath temperaturereaches 130 degF [54 degC]. Note the exact temperature and pressure atthe time of the reading.

6. Discard the sample and thoroughly wash the apparatus with water.

7. To find the vapor pressure, plot pressure versus temperature of the datacollected. Extrapolate to obtain the exact pressure at 100 and 130 degF [38and 54 degC] for reporting.


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JET Manual 38 version 2_1_4298920_01.pdf

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