Effects of Feldspar Content on Microstructure and Property for High-Strength Corundum-Mullite Proppants

Abstract

High strength ceramic proppants are a significant factor during the hydraulic fracturing process. Although many system ceramic proppants have been developed, their strength remained relatively low. In this work high strength ceramic proppants have been successfully prepared by solid state sintering at 1450°C using low grade bauxite and varying contents of feldspar; XRD analysis revealed that the prepared ceramic proppants mainly consisted of corundum and mullite phases. The effects of feldspar content on the microstructure and properties of ceramic proppants have been investigated. With the increase in feldspar content, the bulk density and apparent density slightly declined and then remained steady, while the breakage ratio initially decreased and then increased and achieved the lowest value (9.8%) for 4 wt% feldspar under 80 MPa closed pressure, which satisfied the requirement of Chinese Petroleum and Gas Industry standard (SY/T5108-2014). The study can provide guidance for design of high strength ceramic proppants to employ in low closed pressure oil and gas wells.