Progress in ultra-deep drilling and completion technology in the Sichuan Basin and its implications for extra-deep wells of more than ten thousand meters in depth
The ultra-deep marine carbonate rocks in the Sichuan Basin are rich in oil and gas resources,which is an important direction for searching for super large oil and gas fields and exploring new fields for oil and gas reserves and production increase.However,drilling and completion of ultra-deep wells face engineering and technical challenges such as more complex stratigraphic conditions and more extreme wellbore environments.In order to provide a guidance for the safe and efficient drilling of extra-deep wells of ten thousand meters deep,this paper sorts out the technical difficulties in ultra-deep drilling and completion,systematically summarizes the key technologies in the ultra-deep drilling and completion in the Sichuan Basin,and proposes the development of drilling and completion technologies in the next step.And the following research results are obtained.First,the three-pressure prediction and monitoring technology for ultra-deep complex strata can accurately predict the distribution of pressure system and in-situ stress field in complex strata,and accurately describe the distribution laws of faults,fractures and vugs.And combined with the unconventional well structure prolongation technology,it can improve its ability of casing program design to deal with the drilling in complex strata.Second,the fine pressure control technology for the whole process of drilling,logging and cementing can solve"overflow and leakage coexistence",poor cementing quality and other problems caused by narrow safety density window of drilling fluid in ultra-deep wells and special complex wells.Third,the high-temperature ROP improvement tools such as efficient bit,large-torque screw and torsional impactor can address the engineering difficulties in drilling deep hard-to-drill strata,e.g.bit wear and low rock breaking efficiency.Fourth,the high-temperature drilling fluid system can enhance the ability to guarantee drilling fluid technologies in high-temperature deep wells.The upgraded second generation of tenacious cement improve the high temperature resistance of working fluid,ensuring the construction quality of ultra-deep wells.In conclusion,the development and advancement of ultra-deep drilling and completion technology has made the drilling depth of over 9 000 m come true.Those key technologies provide a powerful support for the efficient exploration and development of ultra-deep oil and gas resources in the Sichuan Basin and play an important role in supporting the scientific drilling in extra-deep strata of ten thousand meters in depth and the discovery of new fields for oil and gas reserves and production increase.
Sichuan BasinUltra-deep strataDrilling and completion technologyTechnological progressExtra-deep well of ten thousand meters in depthDifficulties and challengesDevelopment suggestions
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