Research progress in the evaluation theory and control technology of wellbore instability in ultra-deep strata
Ultra-deep strata is an important field of oil and gas exploration and development in China.Wellbore instability caused by complex geological environment is one of the huge challenges restricting the exploitation of oil and gas resources in such strata.In this paper,the mechanism of wellbore instability in ultra-deep strata is analyzed from the geological and engineering perspectives.Then,the petrophysical-mechanical experiments and the geomechanical parameter evaluation technologies such as constitutive equation,in-situ stress measurement and formation pressure prediction for ultra-deep strata are investigated,and the wellbore stability evaluation theory and control technology for ultra-deep strata are discussed.Finally,some suggestions are put forward to promote the drilling theory and technology for ultra-deep strata.The results are obtained in three aspects.First,the petrophysical,mechanical and physical simulation experimental studies on the environment of ultra-deep strata and the research and development of in-situ stress and wellbore pressure measurement instruments for high-temperature and high-pressure conditions are crucial to understanding the rock and geomechanical properties of ultra-deep strata in extreme environment.Second,the multi-field coupled rock mechanics theory under high temperature and high pressure is the basis for establishing a technical system of wellbore stability evaluation on ultra-deep strata.Third,the integration of wellbore instability control technologies such as multi-section casing program design for large-sized boreholes,HTHP drilling fluid system,leakage prevention and plugging techniques and materials,and theory and tool for precisely managed pressure drilling is a prerequisite for safe and efficient drilling of ultra-deep wells.In conclusion,the development of the evaluation theory and control technology of wellbore instability in ultra-deep strata promotes the drilling of ultra-deep wells in China,and also drives the update and upgrade of theory and equipment for deep engineering survey and ultra-deep oil and gas exploration and development.
Ultra-deep strataOil and gas drillingWellbore stabilityGeological parameter evaluationStrata control
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维普
