well test interpretation 2.pptx

8/13/2019 well test interpretation 2.pptx

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Lecture 02 Types of well test

*


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*In well testing, we provide input and observe

the output.

*Input is the parameter under our control

whereas, output is dependent upon system and

input

*In well testing input is a change in flow rate

and output is the pressure response

*Input may be change in production rates or

change in injection rates (if applicable)


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*Types of Well tests:

Drawdown test

Buildup test

Injection test

Fall off testDrill Stem Test

Interference test


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*Drawdown Test

In a drawdown test, we start flowing a wellthat is initially shut-in, static and stable.

The flow rate is supposed to be constant.


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Drawdown Test


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Suitable for reservoirlimits.

Traditional analysismethods aredeveloped fordrawdown tests.

Difficult to flow a wellat a constant rate.

Well conditions maynot be static or stable.


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*Buildup Test

In a buildup test, a well that is flowing

(ideally at a constant rate) is shut in and

downhole pressure measured as the

pressure builds up.


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Buildup Test


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Constant flow ratecondition is easilyachieved as the flowrate is zero.

Only slightmodification ofanalysis techniquesused for drawdownanalysis is required

Difficult to achieveconstant rateproduction prior toshut in.

Production loss whilethe well is shut in.


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*Injection Test

Similar to drawdown test except that the

flow is into the well rather than out of it.


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*


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Injection rates

are easier tocontrol thanthe productionrates.

Complicated

analysis ifmultiphaseeffects areobserved


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*Fall off test

Similar to buildup test except that

injection is stopped rather than

production. In fall off test we observe

pressure decline.


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Injection ratesare easier tocontrol.

Production loss issmall ascompared to

buildup test

Multiphaseeffects makeanalysis difficult


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*Interference Test

In an interference test, one well is

produced (or shut in) and the pressure

response is measured at another well (or

wells). Interference tests helps to

characterize the reservoir over a largerscale than the single well test.

Interference test is possible with any

type of pressure disturbance

(drawdown, buildup, injection, fall off)


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*Drill Stem Test

This test is carried over a newly drilled

well. We temporarily complete the well

and produce it for a small period of time.

Then we shut in. Again we start producing

but this second flow period is longer.Then we shut in the well again.


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*

*Modern well test analysis a computer aided

approachby Ronald N. Horne


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*

*Continued discussion regarding fundamental

concepts

well test interpretation 2.pptx

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