Parametrized inversion framework for proppant volume in a hydraulically fractured reservoir

Abstract

Hydraulic fracturing is an important technique to allow mobilization of hydrocarbons in tight reservoirs. Sand or ceramic proppant is pumped into the fractured reservoir to ensure fractures remain open and permeable after the hydraulic treatment. As such, the distribution of proppant is a controlling factor on where the reservoir is permeable and can be effectively drained. Methods to monitor the fracturing process, such as tiltmeters or microseismic, are not sensitive to proppant distributions in the subsurface after the fracturing treatment is complete (Cipolla and Wright, 2000).

An electrically conductive proppant could create a significant physical property contrast between the propped region of the reservoir and the host rock. Electromagnetic geophysical methods can be used to image this property (Heagy and Oldenburg, 2013). However, traditional geophysical inversions are poorly constrained, requiring a-priori information to be incorporated through known electrical properties. We examine a strategy to invert directly for the proppant volume using a parametrization of electrical conductivity in terms of proppant distribution within the reservoir.