Key Drilling Fluid Technology in the Ultra Deep Section of Well Ying-1 in the Shunbei Oil and Gas Field

LIN Yongxue1 WANG Weiji1 JIN Junbin

(1.Sinopec Research Institute of Petroleum Engineering, Beijing, China 100101)

【Abstract】Well Ying-1 is an ultra-deep pre-exploration well with key risk deployed by Sinopec in the Shunbei Oil and Gas Field with designed well depth of 9 016.85 m (TVD 8 603.00 m). When drilling the well, we encountered downhole problems including wellbore instability, well leakage and borehole wall sloughing. These problems also easily occur in drilling hard brittle mudstone formations, such as the Silurian Kepingtage Formation and the Ordovician Sangtamu Formation. For this reason, laboratory studies were carried out to analyze the mechanisms contributing to the instability of large section of hard brittle mudstone shale. The reasons for leakage in the Silurian high-pressure sensitive fissured formation and the reasons for instability in Ordovician fractured formations were also analyzed. Based on the basic theory of “multivariate synergistic” wellbore stability, the drilling fluid system SMHP-1 with strong inhibition and sealing capacity was constructed, and the technical measures of mud loss and borehole wall collapse prevention were worked out. The well successfully drilled through a large section of hard brittle mudstone and broken formation to a total depth of 8 588 m without borehole wall instability and drilling fluid loss, setting a record of the deepest onshore well depth in Asia. The field application showed that the drilling fluid system SMHP-1 could effectively solve the problems of wellbore stability and leakage in deep mudstone and broken formations by strong inhibition and sealing capacity and provide best practices for safe drilling of deep or ultra-deep wells in the world.

【Keywords】 ultra-deep well drilling; wellbore stability; leakage protection; plugging; drilling fluid; Well Ying-1; Shunbei Oil and Gas Field;


【Funds】 National Science and Technology Major Project (2017ZX05005-005)

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This Article



Vol 47, No. 03, Pages 113-120

May 2019


Article Outline


  • 1 Difficulties challenging drilling fluid technology in ultra-deep well sections and the analysis of their causes
  • 2 Key drilling fluid technology in the ultra-deep section
  • 3 Field application effects
  • 4 Conclusions and suggestions
  • References