RPI production analysis was used to compare the fracture effectiveness of RCS and EconoProp in oil wells at 6000 psi stress. EconoProp was shown to provide twice the conductivity and twice the effective fracture length of RCS. The authors eliminated an early screenout from the analysis, and then EconoProp provided 258 ft of equivalent length, compared to 107 ft for RCS, a 141% improvement.
The Jepson and Holler Draw fields are located in the Powder River Basin of northeastern Wyoming. The fields were discovered in 1974 and produce 36° API oil from the Shannon sandstone. The Shannon is a 20 foot thick barrier island deposit that occurs between 9,650-10,025' TVD. The reservoir is currently undergoing pressure support from water injection. All producing and injecting wells need to be hydraulically fracture stimulated to produce or inject at adequate rates. Current activity in Jepson and Holler Draw consists of in-fill drilling of new producers as well as restimulation of old producers. Various job designs, fracturing fluid systems, and proppant types have been tried.
This paper analyzes well performance and the effectiveness of fracture stimulations in the Jepson and Holler Draw fields. Information from stimulation pressure histories was examined with several fracture simulators to predict overall fracture length from the various treatments. Daily post-frac production was then evaluated using the reciprocal productivity index (RPI) graphical production-analysis method and combined with analysis from pressure build-up tests to determine permeability-height (KH) and effective infinite conductivity fracture length. The overall fracture length was then compared to the effective infinite conductivity fracture length using reservoir simulation to examine possible explanations for the difference in the two lengths. This comparison was used to draw conclusions about how job design, fracturing fluid systems, and proppant types affected the well performance.
Author(s): W.A. Scott, BJ Services Co.; W.R. Guice, Ensign Oil & Gas Inc.
Paper Number: SPE 71071