【摘要】 实际工程要求对井壁稳定问题做到提前预知,因而井壁稳定实时预测研究意义重大。基于实钻录井和测井资料提出了井壁稳定实时预测方法。将发生变形的井眼看作椭圆形,应用弹性理论的复势解法及叠加原理得到井壁应力分布,从而建立井壁围岩的变形程度与岩石物理力学性质、地应力、孔隙压力、泥浆密度及理化性质的关系,在此基础上由泥浆录井和测井资料,反算地应力及孔隙压力,从地震反演得到的岩石力学模型中提取钻头下方一定深度范围内的地层密度和声波时差数据,计算待钻地层的压力曲线,从而实时预测钻头下井段井壁稳定。该方法应用在川东北部地应力复杂地区,取得了较满意的效果。更多还原

【Abstract】 The borehole instability in practical engineering should be predicted and handled as soon as possible,so a study on the real-time prediction of borehole instability(referring to the prediction of the borehole stability under bit based on the information from drilled sections) is of significance.The present paper introduced a method to predict borehole instability in real time based on actual drilling and well-logging data.The borehole to be deformed was regarded as an ellipse and the stress distribution around borehole derived from the complex potential method and superposition principle was used to correlate the borehole deformation(including collapse,necking,cracking,etc.) with rock mechanical properties,earth stress and pore pressure as well as mud density with physical and chemical properties.Based on these relationships,mud logging and well-logging data were employed to inversely compute earth stress and pore pressure.Subsequently,the density and acoustic travel-time data of strata under the certain depth of bit were deduced from a lithomechanical model established by seismic inversion,and then they were employed to predict the borehole instability under bit in real time.The application of this approach to a northeast Sichuan Basin gained a satisfactory result.更多还原