Production Decline Analysis of Horizontal Wells Intersecting Multiple Transverse Vertical Hydraulic Fractures in Low-Permeability Shale Reservoirs

Abstract

AbstractThis paper reports the development and application of production performance decline analysis techniques that are applicable for the characterization of the well and reservoir properties of low permeability fractured shale gas or oil reservoirs which are completed with horizontal wells intersected by multiple, transverse, finite-conductivity, vertical fractures. This type of well completion is now the most common type of completion technique that is currently being used to develop wells in low permeability fractured shale gas and oil reservoirs in North America.It can be extremely difficult, if not technically impossible, to fully characterize the physical properties of unconventional reservoirs using conventional transient testing methods within a reasonable amount of time or at an acceptable cost. Instead, the production performance of these wells can be evaluated using transient production decline analysis techniques to determine the reservoir properties [permeability and estimated Stimulated Reservoir Volume (SRV)] and the well completion effectiveness [effective fracture half-length and conductivity] of the system.The production decline analyses that have been developed in this work include both graphical production decline diagnostic analyses and history matching with a multiple-transverse fracture horizontal well transient solution using regression analysis techniques. Specialized diagnostic analyses have been developed for the intermediate flow regimes that are commonly exhibited in the transient performance of multiply-fractured horizontal wells to obtain estimates of or limits on the reservoir and well properties, which are then refined using nonlinear minimization techniques in a history matching analysis.A field case history example is presented in this paper to demonstrate the application of the production performance analysis procedures. The evaluation of the reservoir properties and well completion effectiveness of multiply-fractured horizontal wells in fractured shale reservoirs using the transient production performance of these wells is of tremendous importance to the petroleum industry. It has been found that a combined production diagnostic - history matching analysis provides a reliable and accurate means of properly characterizing the properties and production performance of multiple-transverse- fractured horizontal wells in low permeability shale reservoirs.