An Integrated Petrophysics and Geomechanics Method for Fracability Evaluation in Tight Sandstone Reservoirs: A Case Study in the Yingcheng Formation, Jinshan Gas Field, Songliao Basin, China

Abstract

There are abundant gas resources in tight sandstone reservoirs in China, and hydraulic fracturing is essential for developing this kind of resources. Optimizing the highest quality reservoirs for hydraulic fracturing is critical to raising oil and gas production. Therefore, it is very important to evaluate the reservoir fracability. Taking tight gas sandstone reservoirs in the Yingcheng Formation, Jinshan Gas Field as an example, this paper proposes an integrated petrophysics and geomechanics method for fracability evaluation based on the analytic hierarchy process (AHP). In this study, as many as nine influencing factors, including brittleness, brittle mineral content, cohesive strength, internal friction angle, unconfined compressive strength, Model-I toughness, Model-II toughness, horizontal stress difference, and fracture height control are considered in the evaluation model. Both a transfer matrix and a fuzzy matrix were introduced into this AHP model to make the evaluation results more objective. All the influencing factors were derived from the lab experiments conducted on the cores drilled from the Yingcheng formation of six vertical wells in Jinshan Gas Field. The fracability evaluation of the six candidate wells was analyzed based on the proposed evaluation model. According to the evaluation results, the fracability of the six wells was ranked according to the fracability coefficients.