Fault characteristics, reservoir types and distribution prediction in a fault-controlled area in the Ordovician strata of the Tahebei Block, Halahatang Oilfield

The heterogeneity of Ordovician carbonate reservoirs in the Halahatang Oilfield, Tarim Basin is complex, so it is important to carry out evaluation and prediction research. Based on geological and seismic data from the Halahatang Oilfield, this paper studies carbonate fracture-vuggy reservoir location, reservoir spatial distribution, reservoir and fault matching relationship, and inter-well connectivity. On this basis, according to the actual drilling, logging data and production dynamic analysis, the fracture-cavity carving of carbonate reservoirs in the fault-controlled area is carried out. The results show that the fault system evolution of the Halahatang oilfield includes four stages: Early Caledonian to Middle Caledonian, Late Caledonian to Early Hercynian, Late Hercynian and Yanshan. Fault trends and multiple stages of fault development are the main controlling factors for the generation of the fault systems. The increase of the horizontal slip of the fault block will give the strike-slip faults better connectivity. The plane diffusing width of the fault is controlled by the intensity of fault activity and the development degree of deep through-source branch faults. In addition, in order to clarify the spatial morphology and distribution characteristics of carbonate reservoirs in buried hill karst areas, interlayer karst areas and fault-controlled karst areas, targeted reservoir prediction is carried out. Based on inversion results, multi-attribute comprehensive prediction is carried out by combining the data such as attributes, sedimentation and drilling. The prediction results show that the fracture zone in the buried-hill karst area of the Tahebei block of the Halahatang Oilfield has good overall source permeability, connectivity and diffusion-solubility, which is conducive to the formation of large-scale solution pore-fracture-cave reservoirs, and the plane distribution of the reservoirs is continuous with the best reservoir quality, which is the key area of oil and gas exploration and development in the future. The study reveals the development characteristics of Ordovician faults and the distribution areas of favorable reservoirs in the fault-controlled area of the Tahebei Block, Halahatang Oilfield, in order to provide a basis for effectively guiding carbonate oil and gas exploration and development in the deep-ultra-deep fault-controlled areas.