Application of Autonomous Healing Cement Slurry System in Sichuan

Aiming at the problem of damage effect of cementing isolation caused by formation of crack in cement sheath during the development of oil and gas wells, the hydrocarbon-triggered swelling polymer was used as self-healing particles to form an autonomous healing cement slurry system. The experimental results show that when the self-healing particle size is 200-250 nm and the amount is about 10%, the cement stone has better oil absorption healing effect and mechanical properties: the cement stone crack healing rate is 70%-100% within 8 days, and the 2 d compressive strength is 16.2 MPa, elastic modulus 6 GPa. Seepage experiments show that the flow rate of oil and gas in cracks of cement stone larger than 0.1 mm is reduced from 9 g/min to 6 g/min, and the flow rate of cracks smaller than 0.1 mm can be reduced from 6 g/min to 0. This shows that once the autonomous healing cement is damaged, the oil and gas molecules infiltrated into the crack and the self-healing particles spontaneously expand and adhere, then the cracks are gradually repaired. It can realize that the cement has self-healing function. The smaller the crack, the better the self-healing effect. The field application in Sichuan shows that the cementing quality of the autonomous healing cement system reached 88.9%, and the technical casing pressures after cementing and fracturing were not appeared, showing good application effects.