Type curves for pressure transient analysis of horizontal wells in shale gas reservoirs

Abstract

Shale gas has been recently emerged as a potentially enormous resource. Even though significant progresses have been made in the past few years, there appears to be a lack of information regarding the characterization of shale gas formations. A major purpose of the study is to demonstrate how this issue may be addressed by pressure transient analysis for horizontal wells in shale gas reservoirs. Extensive numerical simulations were conducted to model transient pressure behavior of a horizontal well and apply the results to well test analysis in shale gas reservoirs. For the simulation of realistic reservoir flow processes, the model incorporates a number of important formation properties and nonlinear processes in shale gas reservoirs including effects of well vertical location and length, dual porosity/dual permeability model, Klinkenberg effect, non-Darcy flow behavior, and adsorption/desorption under reservoir flow condition in addition to skin effect. Results from numerical simulations for nonlinear gas flow provided various type curves in terms of dimensionless pseudopressure and time for transient pressure responses in horizontal production wells. Results from type-curve matching for synthetic pressure data in shale gas reservoirs demonstrate that the conventional analysis approach may still be applicable for analysis of shale gas reservoirs. The results were shown to be a useful tool for the quantitative analysis on the transient gas flow behavior and determination of formation properties. Copyright 2010, Society of Petroleum Engineers.