Fracture-injection-test interpretation: Leakoff coefficient vs. permeability
- Union Pacific Resources, Fort Worth, TX (United States)
- Texas A and M Univ., College Station, TX (United States)
Determining the leakoff coefficient from a minifracture pressure decline has become a relatively common industrial procedure. A main assumption of the method, which is often referred to as the Nolte analysis, is a constant leakoff coefficient. Frequently there is no constant leakoff coefficient. The definition of the coefficient is based on a constant pressure differential and a prescribed mode of leakoff. In contrast, the analysis for fracture-pressure decline, introduced by Mayerhofer et al., couples unsteady-state linear flow from the fracture with a varying skin effect at the fracture face, and superposes the leakoff history on the pressure decline. This guarantees a correct rate convolution to account for pressure-dependent fluid loss. The reservoir permeability, fracture-face resistance, and leakoff area can be determined. A comparison of the two methods and their relationship is presented in this paper, using real field cases (a deep and a shallow gas reservoir). The authors show that the use of modern well-testing log-log diagnostic plots to determine fracture closure pressure is superior to drawing a straight line on a G-function plot or a square-root-of-time plot.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 549428
- Journal Information:
- SPE Production and Facilities, Journal Name: SPE Production and Facilities Journal Issue: 4 Vol. 12; ISSN 1064-668X; ISSN SPRFEZ
- Country of Publication:
- United States
- Language:
- English
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