The Comprehensive Resech In Petroleum Geology And Objective Optimization Of Saihantala Sag Of Erlian Basin

The Saihantala sag is oil-enriched in the Erlian basin, having lower conversion rate of hydrocarbon resources and bigger exploration potential at the moment, so is a practical and exploration-favor ing areas in Huabei oilfield.Basing on the correlation of sequence stratigraphy and the sedimentary facies studies, Using data of coring, logging and3D seismic prestack depth migration, Focusing on studying of sedimentary systems encircling, identification and evaluation of lithologic traps and key controlling factors of. hydrocarbon accumulation, fine division and correlation of sequence and systems tracts, fine structure interpretation and reservoir inversions of main objective formation been done, the thesis studies the selection of profitable exploration area and drilling target and through research of tectonic characteristic and analysis of the geodynamics of oil-bearing basins, it studies the structure style and formation strategy of the sag and evolution characteristics of structure development. The main contributions are as follows:(1)The lower cretaceous in Saihantala sag is subdivided into four sequences, SQ1(to be the equal of Aershan Formation), SQ2(to be the equal of the first member of the Tenggeer Formation), SQ3(to be the equal of the second member of the Tenggeer Formation) and SQ4(to be the equal of Saihan Formation), with LST, TST and HST systems developed. Being controlled by the boundary fault, Zabu fault and Saisi fault, its thickness increases gradually from the western gentle slope belt to eastern depression zone for each sequence, in which the lowstand systems tract is favourable to development of the sublacustrine fan deposition and formation of lithologic oil reservoirs, and the transgressive systems tract is favourable to formation of large and medium-scale oil-gas reservoirs with large-scale fan delta sandstone bodies.(2)The analyses of regional stress field and tectonic evolution show that Saihantala sag is a Mesozoic-Cenozoic continental depositional basin developed in Hercynian fold belt, with tectonic framework of zonation in SN direction and subregion in EW direction. According to the developmental features of fault and structure, it is subdivided into eight second-order tectonic units:Buhe structural belt, Saibei subsag, Saisi structural belt,Bayanhushu fault step belt, Saidong subsag, western slope,and eastern abrupt slope zones. The study of tectonic evolution indicates that the North and the South of the basement structures is not consistent, which the south is complex and the north is relatively simple. There were significant differences of fault intensity and evolution among Xilin fault, Zabu fault, and Saisi fault, which the south and the midland are strong and the north is relatively weak. These three main faults are slip synsedimentary fault and their development controlled the sedimentation of the Saihantala sag.(3)System of feature of source rock shows, the first member of the Tenggeer Formation and Jurassic System are the main hydrocarbon source rocks of Saihantala Sag. Tenggeer Formation hydrocarbon source rocks are distributed in the East depression, Jurassic hydrocarbon source rocks are distributed in the region, in the region. From the old to the new Saihantala Sag developed13sets of reservoir, pre Mesozoic bedrock insider, bedrock, the Jurassic basal conglomerate, Jurassic igneous rock, the third member of the Aersan massive conglomerate, the fourth member of the Aersan glutenite, The lower part of the first member of the Tenggeer Sai4formation, The upper part of the first member of the Tenggeer conglomerate, the second member of the Tenggeer Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ oil group. Control the accumulation of oil and gas from hydrocarbon source rock and reservoir seal combination, a region of Saihantala sag (the saidong sag) with two belts (the Xilin fault steep slope belt, Zhabu fault zone of the slope), three sets of objective layer (the second member of the Tenggeer, Aershan formation, basal) with good reservoir forming condition, especially Jurassic and the basal slope of the rise disc Zarb fault zone with hydrocarbon migration, accumulation, preservation of the superior conditions, low degree of exploration, is the focus of the next step exploration.