Analysis of variable rate pressure data using Duhamel's principle
Three general methods have been developed for generating equivalent constant sandface rate wellbore pressure data, given simultaneously recorded measurements of variable sandface rate and bottomhole pressure. The numerical schemes for the analysis of variable rate drawdown pressure data are based on the exact Duhamel's Principle Solution for Darcy flow of a slightly compressible fluid of constant viscosity in a porous medium. Schemes for analyzing buildup pressure-rate data are based on an approximate Duhamel's Principle solution which neglects producing time effects. The numerical schemes based on Duhamel's principle may be employed to (1) remove wellbore storage effects on well test data, (2) analyze declining rate reservoir limit tests, and (3) decouple commingled layered systems to yield individual layer properties, provided individual layer sandface rates are measured. The methods are equally applicable to cylindrical or vertically fractured wells in homogeneous or heterogeneous reservoirs. The effect of variation in producing rate prior to shut-in on the maximum shut-in time for which pressure buildup data is analyzable using the classical analysis methods is investigated. In certain cases, rate stabilization prior to shut-in may actually decrease the maximum shut-in time for which data is analyzable.
- Research Organization:
- Tulsa Univ., OK (USA)
- OSTI ID:
- 5160546
- Country of Publication:
- United States
- Language:
- English
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