Performance Evaluation and Field Application of Self-Consolidating Plugging Agents

In light of the low success rate of plugging by conventional compound plugging agents, self-consolidating plugging agents were studied. A fluidized coating equipment was adopted to coat the outer surface of the plugging agents with a layer of epoxy adhesive that can be consolidated at downhole temperature, so as to increase the underground plugging strength of plugging agents. By adjusting the inlet air temperature of the fluidized coating equipment at 50–100 °C, the air outlet temperature at 25–40 °C, and the rate of the spray gun at 0.5–2.0 L/h, the spray, coating, and drying could be achieved. The laboratory experiments of plugging at high temperature showed that the developed plugging agents could resist the disturbance of drilling fluids and the negative-pressure suction. By selecting the specific type of epoxy resin, the dosage of curing agent and accelerator DL-1, the downhole consolidation time of the self-consolidating plugging agents could be adjusted. At 110 °C, the plugging agents began to consolidate after 2 h, and the strength increased to 4.6 MPa after 15 h. Scanning electron microscope photographs of the plugging layers showed that the coating layers were softened and then consolidated as the temperature rose, and the materials bound tightly after consolidation. The result indicated that the self-consolidating plugging agents can greatly improve the success rate of plugging in severely fractured thief zones and provide technical supports for effective plugging.