低渗致密油藏井震联合地应力预测方法研究

Research on Prediction Method of Ground Stress in Low Permeability Tight Oil Reservoir

低渗致密储层日益成为油气开发重点,其储层结构复杂,地质应力分布状况不明,导致井位部署、钻井施工和压裂施工困难大。地应力预测技术能够为其提供有效技术支撑。常规的地应力预测方法依赖于获得的测井曲线,不能很好地满足钻前预测的需求。首先,利用探井获得的岩心试验数据,开展岩石力学分析,并对测井资料计算出的单井地应力进行修正,再运用地应力经验公式,建立由纵波速度、密度、泥质含量组成的区域地应力模型。在此基础上,利用区块内探井和三维地震资料,运用叠前反演方法,得到高精度纵波速度体、密度体和含泥量体,并建立了区域地震地应力模型。然后再利用测井计算的单井地应力计算结果对模型进行校正,预测结果与现场实际获得数据对比,误差较小,预测精度满足生产需要。通过模拟发现,工区北部应力差在20 MPa左右,高于南部工区,有利目标区主要集中在北部。通过地应力模型,优选有利目标区,为下一步区域的井位部署、钻井优化设计和压裂施工起到了重要的技术指导意义。

Low-permeability and tight reservoirs have increasingly become the focus of oil and gas development. The complex reservoir structure and the unclear geological stress distribution have caused difficulties in well location deployment, drilling and fracturing operations. Geostress prediction technology can provide effective technical support for it. Conventional methods of in-situ stress prediction rely on the obtained logging curves, which cannot well meet the requirements of pre-drilling prediction. First,use the core experimental data obtained from the exploratory well to carry out rock mechanics analysis,and correct the single well ground stress calculated from the logging data, and then use the ground stress empirical formula to establish a regional ground composed of longitudinal wave velocity, density, and shale content. Stress model. On this basis, using exploration wells and 3 D seismic data in the block, using pre-stack inversion methods, high-precision longitudinal wave velocity bodies, density bodies and mud content bodies were obtained, and a regional seismic stress model was established. Then, the model is corrected by the calculation result of the single well ground stress calculated by logging. The prediction result is compared with the actual data obtained on site, the error is small, and the prediction accuracy meets the needs of production. It is found through simulation that the stress difference in the northern part of the work area is about 20 MPa, which is higher than that in the southern work area. The favorable target area is mainly concentrated in the north. Through the in-situ stress model, the favorable target area is optimized, which plays an important technical guiding significance for the deployment of well positions, drilling optimization design and fracturing construction in the next area.