A transient semi-analytical wellbore/reservoir model for gas well pressure buildup tests /
It has already been widely accepted that, during a pressure transient test, wellborn effects often change the pressure transient behavior and mask important reservoir information contained in early-time pressure response. This work considers wellborn effects on gas well pressure buildup tests with s...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=732843311&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | It has already been widely accepted that, during a pressure transient test, wellborn effects often change the pressure transient behavior and mask important reservoir information contained in early-time pressure response. This work considers wellborn effects on gas well pressure buildup tests with surface shut-in. Wellbore effects can cause errors in the results of interpretation. The pressure data distorted by wellborn effects can be mistakenly interpreted as a reservoir response. Also the combination of wellborn effects usually make the pressure buildup data deviate from the traditional type curves. Being able to distinguish between wellborn effects and reservoir behavior in the pressure response is very important. A general and rigorous wellborn/reservoir model is desired to help solve the problems. This is the motivation of this research. In this work we present a semi-analytical transient wellborn/reservoir model for gas well pressure buildup tests. The governing equations of the wellborn model are based on mass, momentum, and energy balances for single-phase gas in one-dimensional space. The gas PVT correlation is also used. Different flow regimes (laminar, transition, and turbulence) inside the wellborn are modeled for calculating the friction factor. As one boundary condition, a simple analytical reservoir model is connected to the wellborn model at the buttonhole location using Duhamel's principle. Heat loss effects account for forced- convection heat transfer inside the tubing, heat conduction between tubing and formation, natural convection and radiation heat transfer of annular fluid, and transient heat flow in the formation. A simulator is developed from the model. Pressure, temperature, velocity, and gas properties inside the wellborn can be predicted at any depth during an entire pressure buildup test. Variable wellborn storage, momentum, and thermal effects can be simulated with the simulator. Detailed sensitivity studies show that different combinations of reservoir and wellborn parameters cause different wellborn effects. Forward modeling was performed and tested with field data. Examples are presented to demonstrate how the rate deconvolution method can be performed to remove the wellborn storage effects using the afterglow rate calculated from the simulator and the measured the pressure data. |
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| Item Description: | Vita. |
| Physical Description: | xv, 199 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references: pages 172-176 . |