Enhancing Hydrocarbon Permeability After Hydraulic Fracturing: Laboratory Evaluations of Shut-ins and Surfactant Additives

Abstract

Abstract Fracturing fluid loss into the formation can potentially damage the hydrocarbon production in shale or other tight reservoirs. Well shut-ins are commonly used in the field as a way to dissipate the trapped water into the matrix near fracture faces. Borrowing from ideas in chemical enhanced oil recovery (CEOR), surfactants can be potentially used to reduce the impact of fracturing fluid loss on hydrocarbon permeability in the matrix as well. Unconventional tight reservoirs can differ significant from one another, which could potentially make the use of these techniques effective in some cases while not in others. We present an experimental investigation based on a coreflood sequence that simulates fluid invasion, flowback, and hydrocarbon production from hydraulically-fractured reservoirs. We compare the benefits of shut-ins and reduction in interfacial tension (IFT) by surfactants on hydrocarbon permeability for different initial reservoir conditions. From this work, we identify the mechanism responsible for the permeability damage in matrix and we then suggest criteria that can be used to optimize the fracturing fluid additives and/or manage flowback operations to enhance hydrocarbon production from unconventional tight reservoirs.