Research on Drag Type Multi-stage Fracturing Technology for Casing Damaged Wells

In the process of oilfield development, some casing-damaged wells occur, and the remaining oil controlled by them requires fine subdivision fracturing to tap the potential. Developed Φ95 mm small-diameter packer, added additives to rubber barrels, optimized the combination of cords, and combined the steel body with the salt-bath graded quenching heat treatment process to improve the overall pressure-bearing and fatigue resistance of the packer. At the same time, a small-diameter pressure guiding Sandblaster, the sandblasting port adopts the oblique section porous structure design, which reduces the abrasion. The oil pipe blowout prevention valve is designed, and the repeated switching and sealing mechanism are optimized. Through the indoor and field evaluation tests, the casing-damaged wells with finely divided fracturing process as a whole achieved a temperature resistance of 120 °C and a pressure of 70 MPa, the sand volume of a single set of sandblasters was 230 m³, and there were 11 stages of subdivision fracturing in a single trip, it can be suitable for fracturing wells with casing damage over Φ100 mm, and has been applied to 106 wells in Daqing Oilfield. The technology has successfully solved the technical problems of wellbore shrinkage after casing damaged well repair, fracturing tools need to take into account the technical problems of small diameter, high passing capacity and fine layered fracturing. The network improvement has played a positive role, and the process can also be extended to fine layered fracturing of small cased wells with the same well diameter.