Application of Seismic-Geological Integration Anisotropy Modeling and PSDM Technology to Horizontal-Well Group Deployment in New Exploration Field

Abstract

AbstractNew exploration field of Shale-oil located on Songliao Basin in the northeast of China show good prospects has been found very strong anisotropy and varies greatly from location to another through laboratory measurement of drilled cores. But the thickness of high-quality target layer is less than 10m and average vertical depth is 2500m, conventional seismic migration results cannot support accurate geosteering of horizontal-wells. We adopted the result-driven integrated seismic and geological modeling concept to guide the following processing in order to eliminate the structural errors existing in the seismic processing results of Well-X1 and the trajectory calibration of horizontal wells, the fidelity velocity analysis technology based on the combined constraints of rockphysical analysis firstly, the anisotropic forward modeling results is used to obtain accurate isotropic velocity field, and then the "Well-control + Stratification + Fault-control" modeling technology is used to establish a high-precision velocity model. The depth errors of the seismic and geological model and the horizontal well trajectory are directly calibrated quantitatively in the depth domain after the PSDM (Prestack Depth Migration), and the anisotropic model is modified for iterative PSDM. Finally, the structural errors of the horizontal well trajectory and seismic profile in the correlation between the seismic results of the new method and the vertical well synthesis record increased from 79% to 91%. Then, the anisotropy model was updated by quantitative calibration with existing horizontal-well trajectory in the depth domain, so that the final VTI anisotropic PSDM results and the horizontal well construction error in the depth domain was less than 1‰. The anisotropic PSDM results provide accurate guidance for geosteering, and the posterior horizontal-well verifies the high accuracy of the method. The technology can effectively support the deployment of horizontal-well groups in new fields and the beneficial development and utilization of new types of reservoirs in Daqing oilfield, it also demonstrated that the seismic-geological integration anisotropy modeling and PSDM technology can provide reliable support for the deployment of horizontal-wells in the same type of deep, thin, anisotropic reservoirs.