Coated proppants with self-suspension and tracer slow-release functions

Abstract

Proppants play an important role to increase oil and gas output in shale oil and gas development process. Tracers are used to study the degree of heterogeneity and dynamic equivalence between injection and production wells to judge the state of oil reservoir. However, it is difficult to integrate both slow-release tracing and shale supporting functions in one material. The development of functional coated proppants with tracer slow-release function is of great significance. Here a simple method is developed to introduce a carbon quantum dots (CQDs) into polyvinyl alcohol (PVA) coated proppants and fabricate novel self-suspension proppants with tracer slow-release function. The PVA coating layer on ceramic proppants achieves the self-suspension ability. In the well, the PVA film melted in fracturing fluid and the CQDs were released as a tracer for downhole monitoring. The surface adhesion force of PVA-CQDs coated proppants is 2 times larger than that of ordinary ceramic proppants, and the liquid conductivity of the self-suspension slow-release tracer proppants (SSTP) can reach 51 D cm, which is 22.45% higher than original ceramic proppants at the closure pressure of 40 MPa. This work combined the coated proppants with the quantum dot tracer and obtained a new type of coated proppants with tracer slow-release function, which has a promising significance to improve oil and gas production and conducting cross-well monitoring.