| XueFeng mountain west region is located in the upper Yangtze massif and the eastern edge of XueFeng mountain basement decoupling between orogenic belt, belonging to the XueFeng mountain front to make the transition to the sichuan basin subject areas. The marine strata of the west side of the XueFeng mountain area indicates t large oil and gas exploration potential. This paper focuses on the geological interpretation of Guiyang- sands- Renhuai seismic profile. Combining with the existing drilling and test results record data, the aim is to explore the west side of Xue Feng mountain region sedimentary and tectonic evolution history. This article Combine the field geological survey with indoor rock sample testing method and use the conventional electron microscope, cathodoluminescence and unconventional pressure mercury adsorption method, triaxial compressive shear test to analysis the cover petrology characteristics, the thickness of the caprocks, capping the homogeneous degree, the ductility of caprock and film sealing characteristics of caprock. Tectonic evolution as the main line, it aimed at carrying out the caprock sealing history of oil and gas preservation system origin, and on the basis of the analysis of main controlling factors of oil and gas preservation system, to predict favorable oil and gas preservation area.(1)Through comprehensive analysis the structural evolution and characteristics of west regional in XueFeng mountain, it reflect the Angle of seismic wave field characteristics of unconformity which can determine the XueFeng mountain intracontinental tectonic system before and after experienced Jinning, Caledonian, Indosinian and Yanshanian tectonic movement. Superimposed basins is priority to with epeirogenic early, and late orogenesis. Since proterozoic, it experienced Jinning, Caledonian, Hercynian, Indosinian, Yanshanian and Himalayan construction phase.(2)Field geological investigation, sedimentary characteristics and indoor test analysis show that the lower Cambrian cover layer can be found in Wells Tuo group, ling and tianhe group formation. The lithology of cover mainly include mudstone and limestone. The former mainly includes the dark gray, colored, gray carbonaceous mudstone and silty mudstone, mudstone, the latter mainly includes the dark grey carbonaceous limestone, micritic limestone, argillaceous limestone, etc.(3)Through analysis the oil and gas preservation system in the period of Caledonian, Hercynian Indosinian period and early Yanshan epoch, late Yanshan-Himalayan tectonic evolution stages, etc, the evolution of the characteristics and the characteristics of fluid chemistry- dynamic response of the cover, it restore and reconstruct the caprock sealing history and fluid chemical- trajectory dynamics behavior.It has been cleared to determine that the oil and gas preservation system is controlled by the depositional systems tracts of the cover, the degree of diagenetic metamorphism and deformation of fault displacement intensity, "three yuan" coupling relationship and the hosts of fluid.(4)Through the study on the cause of the oil and gas preservation system, the results show that in the control factors of Siluric accumulation in the eastern Chongqing and western Hubei and peripheral regions, high quality reservoirs control the early shipment together, preservation and form the proximal lithologic reservoir. Fluid potential adjustment control the positioning of the current oil and gas eventually. The control factors of accumulation in Jinsha, the west side of Renhuai and peripheral basins show that the effective reservoir space is the precondition of the combination the hydrocarbon accumulation, the effective hydrocarbon migration accumulation is the important guarantee for the combination of gas reservoir, the favorable oil and gas preservation is key factor to form the lower combination of gas reservoir. The destruction of the preservation conditions of oil and gas mainly characterized by tectonic uplift and denudation and fracture damage. Source bed, reservoir, cap rock combination in the study area can be divided into three sets. The first set of Source bed, reservoir, cap rock combination include Sinian Doushantuo formation hydrocarbon source rocks,crystalline dolostone reservoirs of Dengying formation,and the cover of Cambrian Laobao formation,Niutitang formation and Shipai formation. The second set of Source bed, reservoir, cap rock combination include the source rocks of Cambrian Niutitang and Huayanshi formation,the reservoirs of middle Cambrian and the lower Ordovician,and the cover of lower Ordovician mud shale and marl. The third set of Source bed, reservoir, cap rock combination include lower Ordovician and lower Siluric source rocks, Siluric sandstone reservoirs, and lower Siluric shale as cover.(5)Through the thought of cover and hydrocarbon source rocks common control on the oil and gas preservation system, and with reference to previous studies, it start with gas and oil preservation system of representation, causes and effectiveness, and established marine oil and gas preservation conditions evaluation technology index for Yangtze area. The oil and gas preservation system comprehensive evaluation of Jianghan plain, the western of Xiang ’e, eastern of Chongqing and western Hubei in Yangtze area shows that the oil and gas preservation conditions in J-T2 system, ∈1 system, S system and ∈2 system gradually get better on the longitudinal. Oil and gas preservation system in Shizhu is level 1 which is as well as the most favorable preservation zone or the most favorable exploration zone. Oil and gas preservation system in Lichuan, Sangzhi, Huaguoping, Yichang and Mianyang is level 2, which is favorable preservation zone or favorable exploration zone. While the rest of the blocks are 3 or 4 level effectively effectiveness. |
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