利用井底压力采集短接准确计算地层压力的方法

Precise Calculation Methods for Formation Pressure with Downhole Pressure Collection Joint

摘要:

介绍了现有技术情况下求取欠平衡地层压力的方法以及存在的缺点，在此基础上研制了井底压力采集短接，通过现场试验，实测出关井求压过程中井下气液两相流时的井底压力，根据常规试井理论和地层渗流理论建立一种利用实测数据计算地层压力的新方法，该方法是在井筒内建立压力平衡，采用实际测量出的平衡点的井底压力，消除了套压、立压不稳定以及钻井液密度不准带来的误差，准确计算出该井段各分层地层压力的大小。该方法非常接近实际地层压力，使关井求压计算值误差降低4%左右。

Abstract:

Calculation methods of under balanced formation pressure under existing technology and its defects are introduced. Down hole pressure collection joints are development. Air/liquid double phase pressure down the well was measured during well shut off through in situ test. A new formation pressure calculation method was established based on conventional well test theory and formation transfusion theory and using measured data. The method was established on pressure balance around well wall and the down hole pressure at balance point which was actually measured. It eliminated the errors caused by unstable casing and stand pipe pressure and imprecise drilling fluid density. It can precisely calculate the formation pressures along the borehole. The calculated pressure by the method is much closed to actual pressures. The calculation errors of well shut off pressure were down about 4%.