(Yicai Global) Aug. 21 -- China National Petroleum Corp. (CNPC) successfully completed on-site tests of a high-performance water-based drilling fluid developed by its Sichuan-based subsidiary, Chuanqing Drilling Engineering Co. Compared with existing products, the new drilling fluid is better at preventing well collapses and offers improved stability and lubricity. It is first Chinese-made drilling fluid free of sulfonating agents.

It was injected into a shale gas well in Sichuan's Weiyuan county on May 30 and left there for 69.53 days. The fluid worked well underground at a temperature of 150 degrees Celsius, and its density was as high as 2.2 grams per cubic centimeter, CNPC said.

The water-based drilling fluid has improved heat resistance relative to traditional products, and effectively reduces frictional resistance and torque in drilling operations, a drilling team instructor at Chuanqing Drilling Engineering said.

"The Type II drilling fluid offers enhanced performance in terms of stability, lubricity and collapse prevention compared with its predecessors," said Li Maosen, the head of the team that developed the fluid.

Drilling fluid is an umbrella term for various circulating fluids used in oil and gas drilling operations. Their functions include keeping well bottoms clean, drill lubrication, blowout prevention and drill power transmission.