Performance Evaluation and Application of a High Temperature Temporary Plugging Agent for Fracturing

ABSTRACT: Currently, the transformation of unconventional reservoirs such as tight oil and gas reservoirs commonly uses multi-stage, multi-cluster volume fracturing techniques to enhance production. After perforating, multiple injections of temporary plugging agents are needed to open more fluid pathways and improve stimulation efficiency through diversion fracturing. This is particularly crucial for the repeated stimulation of old wells, where temporary plugging is required to force fracture diversion and connect new remaining oil zones to obtain new production capacity. Therefore, the performance of the temporary plugging agent, including its pressure-bearing capacity, degradability, and the degree of damage to the reservoir, is critical. Some temporary plugging agents on the market cannot fully dissolve in water for complete flowback, which causes varying degrees of reservoir damage. Additionally, some agents exhibit low plugging efficiency and require large amounts to be effective. In practice, hydrolysable polyester-based materials have been used as temporary plugging agents. Their final degradation products are CO2 and H2O, which effectively reduce the damage to the reservoir. These agents belong to polymer-based plugging agents, suitable for fracturing operations in reservoirs with temperatures ranging from 90 to 160 Degrees Celsius. The evaluation is made from the aspects of degradability, plugging performance, and damage to low-permeability cores. The results show that the temporary plugging agent exhibits excellent temperature-controlled hydrolysis properties, achieving effective hydrolysis even at high concentrations, with a hydrolysis rate exceeding 99%. The agent also demonstrates strong polymer bonding characteristics, providing effective sealing of fractures with a pressure-bearing capacity of over 40 MPa, along with stable pressure retention, meeting the requirements for temporary plugging and fracturing in field operations. After degradation, the agent leaves no residue, does not increase viscosity, and causes minimal damage to low-permeability cores, significantly reducing the impact on the reservoir.