Experimental Study of Proppant Crushing and Conductivity Reduction Within Rough Fracture in Shale Gas Formations

ABSTRACT: To investigate the impact of surface roughness on proppant crushing and its effect on fracture conductivity in Shale Gas Formations, laboratory conductivity experiments were performed on standard core columns drilled along hydraulic fractures. The morphology of proppants within the fractures was observed using computed tomography (CT) and scanning electron microscopy (SEM). The results indicate that the roughness of the fracture surface has a greater impact on ceramic proppants than on quartz sand in terms of crushing rate. For high roughness surfaces, quartz sand is suitable for shallow reservoirs, while ceramic proppant is more suitable for deep reservoirs. The rougher the surface of the fracture, the greater the decrease in its conductivity. When the compressive stresses vary from 20 MPa to 50 MPa, the quartz sand crushing rate increases from 10% to 33%, while the ceramic proppant crushing rate grows from 8% to 22%. The CT scan results indicate that the proppant is prone to breakage at the raised area of the fracture surface. The scanning electron microscopy (SEM) results show that the proppant is more prone to crushing and damage at the raised areas of the surface of the fracture. This article innovatively analyzes the crushing of proppants under various rough fracture surfaces, offering guidance for optimizing proppants in different reservoir conditions. 1. INTRODUCTION On a global scale, oil and gas resources remain irreplaceable and non-renewable energy sources. With the decreasing recoverable reserves of conventional oil and gas resources year by year, shale oil, as a new type of unconventional oil and gas resource with great potential, has become an important component of global oil and gas resources (Shah et al., 2010; Davies et al., 2012; Zeng and Wei, 2017). Reservoir fracturing transformation is the core technology for enhancing the utilization of oil and gas reservoirs (Cui A et al., 2014; Saldungaray PM et al., 2015). However, the effective establishment of an artificial fracture network in reservoir fracturing transformation is crucial for creating high-conductivity oil and gas flow channels. The efficient migration and placement of proppants in artificial fractures are fundamental for enhancing the support provided by fractures. (Asabi et al., 2018; Wei et al., 2019; Ghanizadeh et al., 2016; Han, J. A. et al., 2016).