泥页岩地层区域三维地质力学建模与应用

印尼A油田在钻井过程中泥页岩地层井壁坍塌严重，为安全快速钻井，减少复杂事故，文章提出了一种多源地质力学建模方法，该方法综合利用岩心实验数据、已钻井测井数据、地震反演数据和泥页岩失稳机理，对印尼A油田的地质力学参数进行了精细刻画，并建立了该油田三维孔隙压力空间分布、三维弹性模量空间分布、三维泊松比空间分布等三维属性体；利用有限元的方法，计算了该油田三维地应力分布，得到三维安全钻井液密度窗口。该模型有效耦合测井数据、岩心数据、地震数据等多源数据，可在钻井设计和钻井施工过程中根据目标井的坐标位置和井眼轨迹准确获取目标井的安全钻井液密度窗口，已在该油田B-8井中现场应用，模型所得到的安全钻井液密度窗口满足现场实际需要，实钻过程中无复杂，钻井周期相对油田前期平均钻井周期缩短40%。本模型为钻井设计及现场施工确定合理钻井液安全密度窗口提供了技术支撑，为解决泥页岩等易坍塌地层的井壁失稳提供一套地质工程一体化的解决方案。

Three-Dimensional Geomechanical Modeling and Application in Shale Formation

In the process of drilling A oilfield in Indonesia wellbore collapse of shale formation is the most complex. In order to drill safely and quickly, and to reduce complex accidents of the shale formation, in this paper a multi-source geomechanical modeling method is proposed, which comprehensively utilized core experimental data, well logging data, seismic inversion data and shale instability mechanism. The Three-dimensional (3D) mechanical parameters of A oil field in Indonesia, including the 3D pore pressure, 3D elastic modulus, 3D Poisson′ s ratio and the other spatial distribution of the oil field, had been finely characterized. Based on the finite element method, the 3D in-situ stress distribution of the oil field was calculated. And then, the 3D safety density window distribution was also required. This modeling method effectively couples multi-source data such as logging data, core data, and seismic data, and it can accurately obtain the safe mud density window of the target well only by determining the coordinate position and wellbore trajectory of the target well. This method had been applied onsite in well B-8 of the oilfield, and the safe drilling fluid density window was consistent with the actual needs of the site. 40% operation time saved compared the oil field average record, without any downhole problems during drilling operation. This method can provide technical support for determining the safe mud density window during drilling design and field construction, and a set of integrated geological engineering technical scheme to solve the problem of wellbore instability in shale formation.