During the exploration drilling process in the southern margin of the Junggar Basin,due to the complex pressure systems in the deep formations,the pore and fracture pressures of the formation cannot be accurately predicted.The potential for a narrow or no window of safety density will bring significant well control risks to the drilling operations.In the risk exploration wells,technologies and processes such as early kick detection,constant formation ECD drilling,and constant pressure exhaust are employed to improve the precision of pressure control drilling.Through real-time drilling tests,a safety pressure window is mapped,equivalent drilling fluid density is detected,micro-flow dynamic control of the annular pressure is carried out,pressure control parameters are optimized,and the bottom hole pressure remains constant during trips with variable density.The safe drilling fluid density and pressure control values are clarified,ensuring the stability of the drilling wellbore effectively preventing the continuous invasion of high-pressure formation fluids into the wellbore,and achieving safe drilling from narrow density windows to no windows.The experience gained provides technical reference for pressure control drilling in the exploration and development of ultra-deep and high-pressure complex formations.
pressure control drillingpressure windowmicro-flow controlvariable densitywell leakagesouthern margin of Junggar Basin
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