Pressure Transient Analysis of Wells with Horizontal Drainholes
Abstract/Contents
- Abstract
- Drainholes have been drilled in several areas of the world and there is a need to understand these drainage systems for accurate well test analysis. A drainhole pressure transient solution could also aid in the evaluation of production induced drainholes. Although pressure transient analyses have considered many reservoir systems, there has been no publication t o date of pressure transient analysis for horizontal drainholes. This study presents an analytical solution for the transient pressure response of a uniform flux horizontal drainhole in an anisotropic reservoir of finite thickness. The solution also applies for a reservoir with multiple drainholes in a vertical array. The analytical solution is developed using instantaneous source functions, Green's functions and the Newman product method. The solution shows that there are two possible types of transient pressure behavior depending on the length of the drainhole relative to the height of the reservoir. If the drainhole is short, flow is characterized by three flow periods: an initial radial flow perpendicular to the drainhole axis, a transition flow period, and a pseudo-radial flow period. If the drainhole length is long relative to the reservoir height, the initial radial flow period ends instantaneously for all practical purposes. The transient pressure behavior here is identical to that of a uniform flux vertical fracture and is characterized by early time linear flow followed by a transition period and late time pseudo-radial flow.It is demonstrated that the pressure transient response for multiple drainholes is identical to the single drainhole solution if dimensionless variables are defined relative to the number of drainholes. Consequently, the pressure response of a uniform flux vertical fracture can also be approximated by several short drainholes. The solution for infinite conductivity drainholes is also suggested by analogy to the infinite conductivity vertical fracture solution.Log-log type curves are presented for various drainhole radii and can be used in the conventional manner to determine reservoir characteristics including directional permeability or drainhole half length. Short and long time approximations are presented along with appropriate time limits. Finally, conditions for greater productivity than with vertical wells or hydraulic fractures are presented.
Description
| Type of resource | text |
|---|---|
| Date created | June 1985 |
Creators/Contributors
| Author | Clonts, Michael D. |
|---|---|
| Primary advisor | Ramey Jr., Henry J. |
| Degree granting institution | Stanford University, Department of Petroleum Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Subject | Stanford University Petroleum Research Institute |
| Genre | Thesis |
Bibliographic information
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Preferred citation
- Preferred Citation
- Clonts, Michael D. (1985). Pressure Transient Analysis of Wells with Horizontal Drainholes. Stanford Digital Repository. Available at: https://purl.stanford.edu/sx594yg2017
Collection
Master's Theses, Doerr School of Sustainability
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