Laboratory evaluation of a controllable self-degradable temporary plugging agent in fractured reservoir

In order to solve the uncontrollable swelling ratio and degradation time and insufficient strength of conventional self-degradable temporary plugging agent (CSD-TPA), a controllable self-degradable temporary plugging agent (SD-TPA) was proposed. A series of SD-TPA were prepared with free radical polymerization, and the SD-TPA was synthesized by different mass ratios of acrylamide, acrylic acid, hydrophobic monomer, and modified nanoparticles. The effects of modified nanoparticles content, hydrophobic monomers content, temperature, and salinity on its swelling performance, self-degradable performance, and rheological properties were researched systematically. The plugging and unblocking performance of SD-TPA were studied by a core displacement test. The experimental results showed that SD-TPA can be gelatinization after 4 h at 40 degrees C. Under the formation condition, SD-TPA had better viscoelasticity, shear resistance, and higher yield stress than CSD-TPA. The core plugging rate increased from 86.44% to 91.41%, and the formation damage rate decreased to 14.11%. This work provides a new temporary plugging material during hydraulic fracturing process and the swelling ratio, degradation time, and insufficient strength of SD-TPA can be adjusted according to the requirement of fracturing.

Automated summary

To address the issues of uncontrollable swelling ratio and degradation time, as well as insufficient strength, a controllable self-degradable temporary plugging agent (SD-TPA) was developed. SD-TPA was synthesized using different mass ratios of acrylamide, acrylic acid, hydrophobic monomer, and modified nanoparticles. The effects of modified nanoparticles content, hydrophobic monomers content, temperature, and salinity on the swelling performance, self-degradable performance, and rheological properties of SD-TPA were systematically investigated. The results showed that SD-TPA exhibited improved viscoelasticity, shear resistance, and higher yield stress compared to conventional self-degradable temporary plugging agent (CSD-TPA).