Influences of Permian igneous rock on seismic imaging of underlying strata in the Hanilcatam area, Tarim Basin, China

Abstract Large-scale Permian igneous rock is developed in the Hanilcatam area, Tarim Basin. In order to accurately capture influences of thick igneous rock on seismic imaging of its underlying strata based on actual drilling, well logging and 3D seismic data, the simplified Cambrian-Cretaceous geological model is built, and the finite difference method is used to solve the elastic wave equation. The forward modeling of the wave equation is carried out to truly restore the seismic imaging process, and identify the influence of the Permian igneous rock body on seismic imaging of underlying strata, in an attempt to provide certain guidance on exploration and development of Paleozoic oil and gas reservoirs. The results show that the high-velocity high-density Permian dacite has shielding effects on seismic imaging of underlying strata, and the amplitude of the reflected wave of the underlying strata is obviously reduced, relative to that of the periphery of the dacite-overlay zone. Due to the lateral sudden change of lithology, seismic imaging of underlying layers presents obvious deformation and structural anomalies, which are not seismic responses of fault zones or volcanic channels. The wave field of the fracture-cavity body in the chaotic reflection zone or overlay by igneous rock is very complex and the imaging velocity is difficult to select accurately, which leads to false migration features and challenging convergence of seismic reflection displayed as “a string of beads”.