Advanced Hydraulic Fracturing Technology For Unconventional Tight Gas Reservoirs
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Transcript of Advanced Hydraulic Fracturing Technology For Unconventional Tight Gas Reservoirs
Advanced Hydraulic Fracturing Technology For Unconventional Tight
Gas Reservoirs
Students: Pieve La Rosa, A.; Correa, J.; Kubacak, T.; Ouyang, L. and Awoleke, O.
Principal Investigators: Ding Zhu and A. D. Hill
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Outline Project Overview
Experimental Determination of Hydraulic Fracture Conductivity
Static Yield Stress Study and Gel Displacement Modeling
Tight Gas Sand (TGS) Advisory System
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Dynamic Fracture Conductivity Tests(Task 4)
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Introduction
Polymer damage in the fracture reduces fracture conductivity and effective fracture length
Static conductivity tests in general overestimate fracture conductivity
Dynamic conductivity test is designed to simulate filter cake buildup and gel behavior in a condition closer to field conditions
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Conductivity Experiments – Schematics
Leak off Fluid
Data Acquisition and
Processing
Pressure Gauge
Metering Pump
Crosslinker
Hydraulic Load Frame
Hydraulic Load Frame
Core A
Side Piston
Core B
Side Piston
Centrifugal Pump Centrifugal Pump
Base Gel
Valve ValveTap water
Pressure Transmitters
Heating Tape
FracturingFluid
High-pressure Vessel
Diaphragm PumpMixer
Heating Jacket
Proppant
Valve
P-97
P-98P-99
Force
Back Pressure Regulator
Check Valve
Force
Data Acquisition and
Processing
Hydraulic Load Frame
Hydraulic Load Frame
Core Sample
Side Piston
Pressure Transmitters
Heating Jacket
Back Pressure Regulator VentMass Flow
Controller
N2
WaterChamber
Setup for Slurry Pumping Setup for Fracture Conductivity Measurements
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Conductivity Experiments – Core Properties and Dimensions
• Length: 7.25 in• Width: 1.65 in• Height: 3 in• Permeability: 0.05-0.1 md
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Conductivity Experiments – Conductivity Computation
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Conductivity Experiments – Summary of Previous Results
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Static Test @ 30 lb/Mgal
Polymer concentration has a small but clear impact on clean up efficiency
Gas flux has a large effect on clean up efficiency
Presence/absence of breaker has a clear impact on clean up efficiency
Static tests will produce higher clean-up efficiencies compared to dynamic tests
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Conductivity Experiments – Current Work
Addition of new equipment to previous setup• Diaphragm pump to handle solid pumping• Load frame
Accurate load control Accurate vertical displacement measurement Automatic data acquisition
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Conductivity Experiments – Apparatus
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Conductivity Experiments – Range of Test Variables
1. Nitrogen rate: 0.5-3 standard liter minute2. Temperature: 150-250 F⁰3. Polymer loading: 10-30 lb/Mgal4. Breaker: Presence or absence of breaker5. Closure stress: 2000-6000 psi6. Proppant concentration: 0.5-2 ppg7. Fracture fluid pumping rate: 0.7-1.5 gpm
Develop an experimental schedule based on Design of Experiments to identify the most important factors
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Conductivity Experiments – Design of Experiments
Screening experiments in order to determine which variables
are the most important.
Two-factor / multiple factor experiments to refine
information and develop a conductivity model.
Optimization, to determine which levels of the critical variables result in the best
system performance.
Experimental Design allows us to have a more efficiently designed schedule of experiments and determine interaction between multiple and complex system variables.
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Experimental Schedule based on Design of Experiments
No. N2 rate (sl/min) X1 T (
⁰
F) X2 Polymer loading (lb/1000gal) X3
Breaker X4
Closure Stress (psi) X5
Proppant conc. (ppa) X6
Fluid rate (gpm) X7
1 1.75 200 20 half loading 4000 1.25 1.12 0.5 150 30 normal loading 2000 0.5 1.53 3 150 30 no breaker 2000 2 0.74 0.5 250 10 normal loading 2000 2 0.75 0.5 250 30 no breaker 6000 0.5 0.76 1.75 200 20 half loading 4000 1.25 1.17 3 250 30 normal loading 6000 2 1.58 3 250 10 no breaker 2000 0.5 1.59 0.5 150 10 no breaker 6000 2 1.5
10 3 150 10 normal loading 6000 0.5 0.711 1.75 200 20 half loading 4000 1.25 1.112 3 250 10 no breaker 6000 2 0.713 3 150 30 no breaker 6000 0.5 1.514 0.5 150 10 no breaker 2000 0.5 0.715 0.5 250 10 normal loading 6000 0.5 1.516 0.5 250 30 no breaker 2000 2 1.517 3 250 30 normal loading 2000 0.5 0.718 0.5 150 30 normal loading 6000 2 0.719 3 150 10 normal loading 2000 2 1.520 1.75 200 20 half loading 4000 1.25 1.1
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Recent Results
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Time (hours)
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Polymer concentration: 10 lb/Mgal Clean-Up Gas Rate: 0.5 slm Cleanup Efficiency: 57.2%
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Dynamic Fracture Conductivity Experiments-Future Work
Continue running experiments based on the experimental schedule
Identify the most critical factors affecting dynamic fracture conductivity
Determine the effect of these critical factors on dynamic fracture conductivity
Develop correlations for predicting dynamic fracture conductivity based on critical variables
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Gel Damage Investigation(Task 5)
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Gel Damage Investigation - Objectives
Yield stress measurement Investigating the relationship between yield
stress, polymer concentration and breaker concentration
Modeling of gel movement in proppant pack
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Static Yield Stress Measurement
DigitalScale
Water Outlet
Water
Fracturing Gel
A range of polymer concentration was tested
Force change is (static yield stress) measured while water is drained
Building relationship between the gel concentration and yield stress
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20 40 60 80 100 120 140 160 180 200 2200
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Gel Concentration (lb/Mgal)
Yie
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Static Yield Stress of Polymer Gel
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Breaker Concentration (gal/Mgal)
Yie
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tres
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Yield Stress of Polymer Gel with Breaker Concentration
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100 lb/Mgal guar
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Breaker Concentration (gal/Mgal)
FIG
(psi
/ft) Porosity = 0.2
Proppant Pack Permeability = 80 Darcies
Flow Initiation Gradient (FIG) with Breaker Concentration
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Gas Velocity
Formation
Filter CakeDelta P
Gel Movement Modeling
Flow in cylindrical tubeSolve equations of
motion and momentum with appropriate boundary conditions
Velocity profile must be continuous
Stress profile must be continuous
No slip boundary condition at the walls of the tube
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Stress Distribution in Tube
For a given pressure gradient, the linear shear stress profile is given by
This equation is independent of the fluid properties and state of fluid motion (i.e., laminar or turbulent)
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Laminar Flow Newtonian Flow (Gas)
Yield Pseudo-Plastic Fluid (Gel)
shear rate combined with
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Case 1 Case 2 Case 3
Flow Patterns Identified Under Imposed Pressure Gradients
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Future Work- Gel Damage
Identify the critical gas flow rate for gel clean up for tube geometry
Derive equations for 2-phase stratified flow in the turbulent flow regime
Extend the results to flow in porous proppant pack
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Tight Gas Sand Advisory System(Task 6)
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Tight Gas Sand Advisory System – Previous Work
Literature review of hydraulic fracturing practices in tight gas reservoirs
Development and testing of Tight Gas Sand Advisory System
Source: SPE 126708
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TGS – Current and Future Work Communication with Newfield Exploration
Company for data to support current studies
A rigorous field study of the Tight Gas Sand Advisory System
Application of the TGS Advisory System in fracture treatment design
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Tentative Field Study Plan Receive stimulation and production data for the Cromwell
formation in the Arkoma Basin from Newfield Exploration Company
Compare the stimulation treatment designs and well performances to the suggestions made by the Advisory System
Review micro-seismic and pressure data from fracture treatments
Optimize the stimulation design for the Cromwell formation using the results of the field study
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TGS – Advanced Treatment Design Combine information from….
• TGS Advisory System• Dynamic Fracture Conductivity Experiments• Gel Damage Studies
….To develop an optimized fracturing design methodology.
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Thank youPrincipal Investigators: Dr. D. Zhu and Dr. A. D. Hill
Harold Vance Department of Petroleum Engineering Texas A&M University 3116 TAMU, Richardson Building College Station, TX 77843-3116
Advanced Hydraulic Fracturing Technology For Unconventional Tight
Gas Reservoirs