Coping methods for low-permeability and high-pressure formations with narrow pressure windows in the western South China Sea
High-pressure and low-permeability strata are widely developed in the Yingqiong Basin in the western South China Sea.The low-permeability and high-pressure strata may not overflow when the pump is turned on under conditions of low specific gravity.There may even be no casing pressure for a short period of time when the pump is shut down,resulting in the formation of stabilized strata.The circulating gas measurement was relatively high,and the gas in a single pipe was obvious.During the drilling process,it was found that grouting was difficult and overflow occurred.In addition,high-temperature and high-pressure wells usually have narrow pressure windows.When the high-pressure and low-permeability formations are exposed at low specific gravity,it often happens that the formation has not been stabilized after increasing the specific gravity until there is no operating window.If the specific gravity is continued to increase,there is a risk of leakage,and the drilling proceeds to the next step.Operations involve well control risks.Point at the above problems,this article summarizes the method of field exploration of pressure in low-permeability formations,and also summarizes the evaluation method of whether low-permeability and high-pressure formations can be drilled for further operations without complete pressure stabilization and without a window to increase the specific gravity.
High pressure and low permeability formationnarrow pressure windowPressure gropingTrimming evaluation
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