On November 11th, China National Petroleum Corporation (CNOOC) successfully completed the core extraction operation for complex formations in key exploration wells in Changqing Oilfield using its latest developed Large Particle Wellbore Coring Instrument (HRCT). 27 core samples were obtained in one go, with a 100% recovery rate, and the core extraction results were accepted by Party A.

The key exploration well deployed by the natural gas exploration project team in Changqing Oilfield is mainly located in carbonate rock formations with high rock hardness and difficulty in coring. Traditional rotary wellbore coring instruments are unable to meet the operational requirements.

Compared with traditional rotary wellbore coring instruments, large particle wellbore coring instruments use mechanical direct drive instead of hydraulic drive for rotary drilling, with high torque, stable and controllable speed, miniaturization, modularity, stronger reliability, better environmental adaptability, and higher success rate of coring. By combining design requirements and geological data, China National Petroleum Corporation (CNOOC) developed a detailed construction plan and risk control measures. The instrument was used to safely and effectively complete the coring task, providing an important basis for accurately obtaining reservoir parameters.

The innovative scientific research and management mechanism of CNOOC Logging relies on the "Basic and Frontier Reserve Technology Research of Logging Applications" of ten major scientific and technological projects. After three years of technical research and development, it has overcome key problems such as high-temperature DC brushless motor control, high-efficiency mechanical direct drive, high-power cable power supply and anti-interference communication, and created a large particle wellbore coring instrument with completely independent intellectual property rights.

This instrument has been applied in 6 wells in Changqing Oilfield, Fushan Oilfield in China, and Indonesia Block abroad this year, collecting a total of 114 rock cores, creating favorable conditions for subsequent large-scale promotion and application.