Well Decline in Fractured Reservoirs with Fractal Geometry
Abstract/Contents
- Abstract
- This report addresses the problem of well decline for fractured reservoirs with fractal networks of fractures. The fracture network is treated as a continuum of generally noninteger dimension, additionally characterized by its degree of connectivity expressed in terms of the spectral dimension of the fracture set.The case when adsorption is an important storage mechanism in the reservoir is considered by including an additional term in the partial differential equation with the mass of adsorbed fluid represented by a Langmuir isotherm parametric approach. The partial differential equation governing tlhe pressure distribution is solved using a numerical solver and the flow rate for the case of constant wellbore pressure is computed. The effect of the geometrical parameters of the fractal fracture set, the adsorption characteristics of the reservoir rock and the skin factor on the well decline are presented.Well decline in reservoirs with fractal networks of fractures is found to obey a power law of time. This type of decline corresponds to the empirical generalized hyperbollic decline. The controlling factor for the rate of flow rate decline is the spectral dimension of the fractal fracture set. In the presence of adsorption storage the decline is delayed and at late times the controlling factors of the flow rate decline are the mass fractal dimension of the adsorbed phase space and the connectivity parameter of the fractal fracture set.Application of the model to field cases was possible for a tight gas reservoir and a geothermal vapor dominated reservoir with significant adsorption. Nonlinear estimation of parameters gave the values for two out of five model parameters for the tight gas reservoir where adsorption was not present and of three parameters out of eight parameters for the geothermal reservoir. Although coalbed methane reservoirs could be analysed within the same model framework, provisions for two phase flow must be made, as initial dewatering of coal seams is part of the production history.The usefulness of the model approach over the more traditional empirical decline curve analysis when analysing well decline data resides in the fact that variable well pressure schedules can be easily accommodated in the analysis. Where applicable, the method is a convenient short cut for the problem of upscaling in single phase fluid flow in fractured reservoirs.
Description
| Type of resource | text |
|---|---|
| Date created | October 1995 |
Creators/Contributors
| Author | Tudor, Monica |
|---|---|
| Primary advisor | Hewett, Thomas A. |
| Degree granting institution | Stanford University, Department of Petroleum Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Genre | Thesis |
Bibliographic information
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Preferred citation
- Preferred Citation
- Tudor, Monica. (1995). Well Decline in Fractured Reservoirs with Fractal Geometry. Stanford Digital Repository. Available at: https://purl.stanford.edu/bj615mb0587
Collection
Master's Theses, Doerr School of Sustainability
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