Well Test ObjectivesWell Test Objectives1. Identify and Obtain reservoir fluids; oil, gas

& water2. Determine basic reservoir parametes;

productivity (PI), permeability(k), skin (S), initial Resv. Pressure (P*) & Resv. Temp.

3. Well potential & deliverability (gas well) : It may be mandatory to proof field commerciality

4. Boundary & irregular conditions Reservoir (GOC, OWC & Reservoir Limit)

WELL TESTING METHODSWELL TESTING METHODS

• HOLE CONDITION:– OPEN HOLE– CASED HOLE

• TOOLS RUN IN HOLE :– WIRELINE TESTING : RFT, MDT & DST (IT WAS)– PRODUCTION TEST WITH COMPLETION STRING

IN PLACE : DST

Surface Test Equipment

Downhole TestEquipment & Tool

DST & TCP

WELL TESTING SCHEMATICat

Cased Hole

Subsea SafetyEquipment

DOWNHOLE TESTING EQUIPMENTOpen-Hole Sampling Equipment

RDT & RCI are equivalent with RFT/MDT

Baker RCI®

Halliburton RDT®

Formation Test Tool (FTT) sample chambers hold 420cc to 3 gallons of

reservoir fluid depending on make and model.

Open hole samples aid production and facility designs and are sometimes used

for PVT studies.

1ST GENERATION

RFTREPEATED FORMATION TESTER

- unlimited pressure survey- 1 to 2 fluid sampling

2ND GENERATION

MDTMODULAR FORMATION DINAMIC

TESTER- unlimited pressure survey- many fluid sampling (unlimited?)- able to identify fluid type- able to replace(pump out) unrequired fluid sample

SCHLUMBERGER

DOWNHOLE TESTING EQUIPMENT

RFT / MDT

Mud pressure

Reservoir pressure

Build-up pressure

Example RFT Record

Wireline

Open Hole Testing RFT/MDT/RDT/RCI/etc.

• To identify the reservoir pressure

• To identify the fluid content

• To estimate the permeability

• To estimate the productifity

• To define the fluid contact (OWC, OGC and GWC if any)

Fluid Contact Determination with fluid gradient from RFT

oilwater

RFT depth

Water Gradient 0.433 psi/ft

pressure

dept

h

Oil G

radient 0.367 psi/ft

OWC

Performing Well Test with DST

• Clean up (flow)• Shut-in• Main flow (one period or

flow-after-flow, flowing test with 4 to 5 different choke size)

• Main Build –up (shut-in)

Selective Layer Testing

8 1/2” 7” @ 17690’

12 1/4”

17 1/2”

9 5/8” @ 15500’

26”

Layer B

Layer A

20 ft @ 500’

Example :TEST STRINGDST & TCP

Example

: Pressure

Testing

Result

Build up data analysis

K = 375 mDS = 21 P = 4200 psia4050

[psi

a]

40 60 80 100 120

45000

[Msc

f/D

]

Production Period

Build up period

Pressure, psia

rates

Sanding ControlTest

Testing time, hrs

[Msc

f/D]

45000

4050

[psi

a]

40 60 80 100 120

Well

Productivity

AOFP = 344 MMscf/dCGR = 24.5 STB/MMscf/d

Tested gas and condensate rates can be increased to 125 MMscf/D and 3100 BPD

2.5E+5

IPR plot3500

50000

1500

1.5E+5 3.5E+52.5E+5

Gas Rate, Mscf/d

Pres

sure

, psi

Testing

Risk Factors

Layers communication due topoor cement bondHigh pressure and temperatures(over 350°F)Pressure and fluid loss throughpackersAnnulus-tubing fluid communicationWater coning or sandingLayers crossflow

THE ROLE of WELLSITE/DEVELOPMENT GEOLOGIST (DG)

in WELL TESTING

OPEN HOLE TESTINGwith RFT/MDT

CASED HOLE TESTINGwith DST

DG Propose/selects the testing/perforation sand, interval and depth

Estimate the reservoir fluid contents and it’s static pressure

Provide the reservoir rock parameter for testing analysis such as lithology, porosity and permeability if any (from log, or qualitative)

Stop the testing when unsafe operation Testing Engineer (TE) decision

Decide testing duration TE decide flow & shut-in periods. TE also selects choke size for flow testing.

Select taken fluid sample TE decide fluid sampling methods. And responsible for fluid sample handling

As Operation Witness will validate & analyse the result

TE is prime Operation Witness and will validate & analyse the testing result.DG & TE will be along selecting the

perforation method

PERFORATION1. THROUGH CASING GUN

Hyperjet/HSD(high shot density)2. THROUGH TUBING GUN Enerjet3. TCP (Tubing Conveyed Perforation)

GUN TYPES

DG and/or Wellsite Geologist Responsibilities

in Perforation Job1. Define the perforation intervals at

porous zone & hydrocarbon zone (pay zone.

2. Evaluate and prepare the perforation design such as gun type, size, SPF (shot per ft), Spacing (angle between two shots), charge/explosive type; penetration deep and entrance hole.

3. Perforation environment (fluid type in the hole); using mud or brine water or special completion fluid, under/over balance.

4. Witness the gun loading, correlation, shooting result (whether all charges exploded or not) “SAFETY FIRST”

PERF. At Net pay