Recently, Daqing Drilling successfully completed a pressurized coring operation at the Hao 20 well in the Ordos Basin, setting four new records within PetroChina Coalbed Methane Company’s Hancheng Block: the longest cumulative coring footage for a single well, the highest core recovery rate, the largest number of core barrels used, and the most comprehensive coring intervals. This achievement has overcome long-standing difficulties in coal seam coring in the area and provided a powerful new tool for unconventional oil and gas exploration.

Hao 20 is a vertical evaluation well deployed by PetroChina Coalbed Methane Company on the eastern part of the Yishan Slope in the Ordos Basin. Designed to a depth of 2,506 meters, the well completed 95.77 meters of pressurized coring and serves the critical task of evaluating reservoir characteristics and gas content in the No. 5 and No. 8 coal seams. It also explores shale reservoirs in the Shanxi and Benxi formations of the Daning–Jixian block, as well as the gas-bearing potential of limestone in the Taiyuan Formation and carbonate reservoirs in the Majiagou Formation.

Coalbed methane reservoirs in the Hancheng Block are characterized by complex stratigraphy and gas that easily escapes, making it difficult for conventional coring technologies to preserve in-situ reservoir conditions. Any loss of original core integrity would directly affect reservoir evaluation and gas content testing, thereby influencing regional exploration decisions.

To address the complex geological conditions of the Hao 20 well, the coring team from the Engineering Technology Transformation and Promotion Division of the Daqing Drilling Engineering Technology Research Institute upgraded its independently developed DQBYM194-80 pressurized coring tool. By improving the self-locking ball valve sealing structure, the team successfully resolved sealing challenges under high-pressure formations.

The success of the operation relied on close cooperation between the Shaanxi–Shanxi Project Department of the Western Drilling Company and the Daqing Drilling coring team. Clear division of responsibilities and close coordination created an effective working mechanism combining strong drilling support with robust technical backing.

A construction plan featuring “precise layer targeting, dynamic pressure control, and full-process monitoring” was implemented. Downhole temperature and pressure were tracked and recorded in real time, while key parameters such as weight on bit and rotation speed were finely adjusted to ensure close matching between coring operations and formation characteristics. The 30607 drilling crew optimized well trajectory in advance, fine-tuned the drill string assembly, and maintained a stable downhole environment. Leakage control achieved a 100% success rate, and maximum well deviation was limited to 1.42 degrees, ensuring both wellbore safety and quality.

Throughout the operation, the joint team adhered to strict standardized procedures, with 24-hour on-site technical guidance and real-time equipment monitoring. Rapid responses to sudden formation pressure fluctuations effectively prevented core contamination and tool damage.

The successful application at Hao 20 demonstrates that Daqing Drilling’s special coring technology has reached an industry-leading level. A mature operational model combining customized tools, refined processes, and full-process monitoring was established. The project delivered 94.22 meters of high-quality pressurized core, with a coal seam core recovery rate of 98.38%, exceeding the design target by 18.38 percentage points. Crucially, the independently developed tool achieved full pressure preservation from downhole coring to surface retrieval, maximizing restoration of in-situ reservoir conditions and enabling more accurate geological models for key production layers in the Hancheng Block.

This technological breakthrough provides critical support for coalbed methane exploration in the Ordos Basin and highlights the strong application potential of Daqing Drilling in unconventional oil and gas exploration. The company’s coring tools have been tested in nearly 1,000 wells across major basins including Songliao, Hailaer, Shaanxi–Shanxi, Sichuan–Chongqing, and Xinjiang, with an average recovery rate consistently around 98%.