Choice Of Northwestern Sichuan The Xiangxi Geological Evaluation And Exploration Targets

Under the guide of petrogeology, sedilithology, reservoir-geology, hydrogeology, structure-geology and seismology, using the drilling data> well-logging data and seismic data fully, combing the research achievements in the area and make an synthetic evaluation on the conditions of oil & gas in the northwest part of Central Sichuan, on the basis of the research on its lithology, lithofacies, reservoir condition, research fracture prediction and its structure conditions; We have a selection of its exploration targets. The research achievements in this paper are as follows:a. It is pointed out that T₃x Formation in central Sichuan major in the deposit system of loch beach dam and river-delta deposit system secondly. Both the two deposit systems have fine geological conditions with developed reservoir.b. Lower porosity, lower permeability, small pore and minute throat are the characteristics of T₃x Formation reservoir, sometimes there are higher porosity relatively. The reservoir pore types include residual integranular pore, intergranular and intragranular solutional void mostly.c. Proposed that both deposition and diagenetic control physical property of T₃x Formation, which are the major controlling factors affecting its reservoir development. The more material the structure of rock structural grain sorting and roundness, the bigger the reservoir porosity, and with the increase of the fusible ingredient such as feldspar, the porosity become bigger; the primary pore is badly destroyed by compaction and cementation; but the zonary structure of clay mineral stop the further development of cementation, and conserve residual intergranular pore effectively; the reservoir porosity evidently grow with corrosion; the fracture can improve reservoir permeability.d. It is considered that the reservoir of the research area is more developed than Nanchong-Chongxi area, in vertically the T₃x⁴ formation is popularly developed, Secondly T₃x² member, and T₃x⁶ member is much worst. Jinhua district is mostly developed at lower part of T₃x⁴ member, which is relatively high pore reservoir; And Qiulin district is not only developed in the middle of lower part, but also in the middle of upper part of T₃x⁴ member. In laterally, the reservoir become better and better from southeast to northeast, both from Jinhua district to Qiulin district and from well J106E to well J17 and to well J31 all have the same trend.