Type Curves for Pressure Transient Analysis of Horizontal Wells in Shale Gas Reservoirs

Abstract

Horizontal drilling and hydraulic fracturing are necessary to reach economically success in shale gas reservoirs. Pressure transient analysis (PTA) for shale gas reservoirs requires comprehensive understanding related to nonlinear gas flow process as well as hydraulic fracture properties. Even though significant progress has been made in the past few years, there appears to be a lack of information regarding PTA of shale gas formations. A major purpose of this study is to demonstrate how this issue may be addressed by type curves for multi-fractured horizontal wells in shale gas reservoirs.To simplify the mechanism, PTA of horizontal wells in shale gas reservoirs was implemented first. Extensive numerical simulations were conducted to model transient pressure behavior of both horizontal and multi-fractured horizontal wells and applied the results to well test analysis in shale gas reservoirs.The horizontal wells part presents the impacts of well geometries and flow parameters as well as shale gas reservoir system on production behavior and flow regime on PTA. For the multi-fractured horizontal wells, a comprehensive reservoir simulation has been applied to investigate the characteristics of pressure transient responses under the influences of hydraulic fracture properties and nonlinear gas flow mechanism.Results from numerical simulations provided various type curves in terms of dimensionless pseudopressure and time for transient pressure responses in horizontal wells and multi-fractured horizontal wells. Type curve matching for synthetic pressure data in shale gas reservoirs demonstrates that the conventional analysis approach may still be applicable for the 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.