奥陶系地层压力剖面预测新方法研究

利用欠平衡钻井能及时发现并保护油气藏,其关键是要准确预测地层压力剖面。根据井壁失稳力学机理,分析地应力、地层孔隙压力、拖拽力和温度对井壁应力分布影响,建立欠平衡钻井的井壁力学模型;利用Boit理论及室内实验,建立奥陶系地层孔隙压力模型。研究结果表明:有效应力与体积弹性模量呈指数关系;拖拽力和温度对井壁应力分布的影响不可忽略。对奥陶系地层进行压力预测,经现场验证,该预测结果对现场施工具有很好的指导意义。

New Method of Studying on Formation Pressure Profile on Ordovician

oil and gas reservoirs can be detected and protected timely using underbalanced drilling technology, the key is to ensure borehole stability. Based on mechanical mechanism of borehole instability, analysis the effect of in-situ stress, formation pore pressure, drag force and temperature on the borehole stress distribution, develop borehole mechanical model on underbalanced drilling. The pore pressure model of carbonate rocks can be studied using Boit theory and laboratory experiments; Studies have shown that the relationship between effective stress and bulk modulus is an exponent; It can not be ignored that the effect of drag force and temperature on the borehole stress distribution in underbalanced drilling; Three pressure profile of carbonate rocks can be predicted using this model, compared to the measured data, it is proved that this model is suitable for the field operation.