Multistage hydrajet-fracturing combines hydrajet perforating and hydraulic fracturing to perform separate, sequential fracture stimulations without mechanical packers. It can reasonably place fractures according to geological condition, and then accurately treat them. Without packer, it uses dynamic isolation to seal flow into target, saving operating time and lowering operating risk. Therefore, the process not only especially adapts to stimulate open hole, but effectively treats slotted liner completion.
The mechanisms and fluid dynamics of multistage hydrajet-fracturing technology are investigated with numerical simulation and laboratory experiments. More than 70 oil and gas wells have been successfully treated using this technology since 2009. On average, three hydraulic fractures with total 120m3 proppants were placed at strategically selected locations in well, typically several hundred meters apart without sealing equipments. The deepest treatment in oil well 203-19 in Zhongyuan oilfield, using tubing string, was 3692m, and surface pressure reached 88MPa. Significant stimulation results were achieved in these wells. For example, production increased by more than 50 times after stimulation to the gas well XS311H in Sichuan oilfield. The oil well 92-2 in the Zhongyuan oilfield, which had been a dead horizontal well, has been revived using this technology with average oil production of 15 tons per day.
Multistage hydrajet-fracturing stimulation shows promising feature for horizontal, vertical, deviated, and even multilateral wells.