Geological Methods for Evaluation in a Brave New World – Unconventional Reservoir Monitoring

Abstract

Summary The physics of unconventional reservoir development boils down to two processes – reservoir stimulation during hydraulic fracturing, and fluid recovery during depletion. How these two processes come together and interact with naturally present, pre-existing geological attributes (faults, mineralogy, stresses etc.) to affect well performance is a subject of great interest and fierce debate. At Shell, we have attempted to answer this question by deploying comprehensive instrumented pilot programs that employ various reservoir monitoring technologies including but not limited to microseismic monitoring, chemical tracers, fiber optics, downhole pressure gauges and production logs. These technologies are often implemented in shale gas (SG) and liquid rich shale (LRS) plays to provide insight into the following:  Stimulated Rock Volume produced during completions  Hydraulic fracture half-lengths  Mechanical stratigraphy and geomechanical profiles The above are all important inputs needed to make informed decisions regarding well spacing, well lengths, stage spacing, stage placement, well orientation and well landing – decisions that can challenge or ease the economic feasibility of a project. These data also have the potential to serve as an integrated platform where geologists, geophysicists, production, reservoir and geomechanical engineers can converge to discuss the key uncertainties and issues that affect unconventional reservoir development. However, in order to properly leverage the power of integrated analysis, we must develop novel and innovative workflows that combine existing geological characterization techniques (3D seismic interpretation, core interpretation and analysis, static modeling etc.) with reservoir monitoring and engineering data.