SPE DISTINGUISHED LECTURER SERIESis funded principally

through a grant of the

SPE FOUNDATIONThe Society gratefully acknowledges

those companies that support the programby allowing their professionals

to participate as Lecturers.

And special thanks to The American Institute of Mining, Metallurgical,and Petroleum Engineers (AIME) for their contribution to the program.

Giovanni Da Prat, Ph.D.

Da Prat Consulting

Well Testing ManagementImpact on Reservoir Evaluation

and Well Productivity

Presentation Outline

Objectives and Concerns

Environment and Risk Factors

Testing Management

Conclusions

Field Cases of Application

Well Testing Alternatives

Well Test Objectives

Temporary well completion to acquire well andreservoir data under controlled conditions

Testing management approach is a key driverto achieve evaluation objectives

Data interpretation providesvaluable reservoir managementinformation

Industry Concerns and Remarks

Used to minimize uncertainties and increase profit

Avoided investment in attractive prospect

It may be mandatory to proof fieldcommerciality

Operationally successful job however objectiveswere not obtained

Multilayer Testing Environment

Layer B

Layer A

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’

Basic Evaluation Program

Testing Time and ProgramSampling Procedures

Perforation

Well Testing

Completion orAbandonment

Well Test Design

FlowNo

Yes

InformationObjectivesCostsGeologySeismicPetrophysicsOpen hole testsWireline Testers

Testing Risk Factors

Layers communication due to poor cement bond

High pressure and temperatures (over 350°F)

Pressure and fluid loss through packers

Annulus-tubing fluid communication

Layers crossflow

Water coning or sanding

Testing Management Key Issues

Test Design

Testing Time

InformationValue

FluidSampling

AvailableTechnology

Expertise

Risk Factors

Cost - Effective

Testing Field Cases

The following field cases are intended to illustrate testingapplications and successful achievement of evaluation objectives

Well Production Increase (Ref. SPE ATW Workshop, London)

Reservoir and Well Evaluation (Ref. SPE 81065)

Reservoir and Well Evaluation

0 1Km.

Interpreted Seismic Section

well

Confirm seismic and geologyexpectations

Obtain reservoir parametersand well potential

Evaluate dynamic conditions forsand flow

Obtain fluid samples for PVT analysis

Temporary Completion

Well completion for testing

TCP-DST Equipment

Reservoir is isolatedafter testing

Tested Reservoirs

Testing History

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

Testing time

28%Reservoir Testing

10%DST pulling out

12%Well Control

9%Reservoir isolation

41%

DST string settingand running todepth

Reservoir model consistent with seismic interpretation

Testing Evaluation

Testing program changes based on team decisions

Tested gas and condensate rates are sustainable

Considerable well skin effect

Development Well

Tested Reservoirs

Complete using 7 inch production tubing

Perforation-Completionand Testing Strategy

Use high shot density guns

Flow after flow and isochronal type of tests

Testing evaluation to be obtained in 2.5 days

Well Completion

Layer B

Layer A9 5/8 in. SHOE

No-Go Nipple Profile

7 in. Production Tubing

9 5/8 in.Permanent PackerNo-Go Nipple

Profile

7 in. SHOE

Testing History

2500

3000

5 15 25 35 45 55

Production period

Build-up period

Pressure, psia

Rates

155 25 35 45 55

Testing time, hrs

[MM

scf /D

][p

sia ]

3000

2500 E -3 0 .0 1 0 .1 1 1 0 1 0

1 E + 7

1 E + 8

1 E + 9

Log-Log plot: dm(p) and dm(p)' [psi2/cp] vs dt [hr]

Build up data analysis

Conclusions

Increased and optimized tested production rates

Obtained testing results are in agreement with test design

No evidence of fault or aquifer

Water production due to poor cement bond

Well Testing Alternatives

Information

Sampling

HeterogeneitiesBoundariesConnectivity

Permeability andskin

Pressure

Scale of Measurement(large)

Static data

Quality depends on fluid type and contamination

degree

Scale of Measurement( Up scaling Uncertainties)

Initial Reservoir Pressure

Comments

Wireline FormationTesters(WFT)

Geology andGeophysics, WFT

GeochemistryCross well seismic

WFT, Cores and Logs

WFT

Method

Testing data acquisition and interpretation methodology has advanceddramatically during the last ten years, still there are manycases were evaluation objectives are not obtainedat all or questioned. There are no alternativesto well testing and appropriate testingmanagement is the solution formost of the cases

Conclusions