Prospect Analysis Of Petroleum Exploration Of Mesozoic In Hongmiaozi Basin,Liaoning Province

With the deepening of domestic oil and gas resources exploration,more and more researchers have turned their attention to the Mesozoic residual faulted basin group in the southeastern periphery,Songliao Basin.The Hongmiaozi Basin is mainly located in Huanren County and Xinbin County,Liaoning Province,with an area of about 350km²,and is one of Mesozoic faulted basins in the southeast periphery of Songliao Basin.The main target strata are the Houjiatun formation of Middle Jurassic,Yingzuilazi formation,Linzitou formation,Xiahuapidianzi formation and Hengtongshan formation of Lower Cretaceous.By combining the analysis of gravity,magnetic,electrical data and drilling data in the basin,it can be seen that the Hongmiaozi Basin was a multilateral irregularity single fault clastic lake fault basin controlled by the NE-oriented main fault F₁ in the northwestern part of the basin during the Middle Jurassic to Early Cretaceous.The F₁fault is a NE-oriented fault which controlled the development of Houjiatun formation to Hengtongshan formation during the fault depression period and then suffered the extrusion reversal in the later period.The F₂ fault is a SE-oriented backstroke nappe fracture in the southeast of the basin.The F₃ fault is a NNW-oriented small positive fault in the eastern sub-concave.The F₆ fault is a NW-oriented backstroke nappe fracture in the southwest of the basin.Overall,it presents a"two clamping-one uplift"structure pattern of western fault depression-middle nose uplift-southeast subconcave.The basin has experienced 3 major tectonic movements and suffered 2 strata denudations,which can dilibeletely divided into 5 stages,sedimentary period of faulted lakes of Houjiatun Formation in the Middle Jurassic,uplift erosion period of late Jurassic,strong volcanic activity period of Guosong Formation of Early Cretaceous,sedimentary period of faulted lakes of Yingzuilazi Formation to Hengtongshan Formation of Early Cretaceous,uplift and denudation period of late Cretaceous.Based on field geological survey data and drilling core data,four sedimentary facies types mainly developed of Mesozoic strata of Hongmiaozi Basin are identified:alluvial-fan facies,lacustrine facies,fan-delta facies and sublacustrine-fan facies,and6 sedimentary subfacies,11 sedimentary microfacies are further identified.In addition to the Guosong Formation of Lower Cretaceous,the Houjiatun Formation,Yingzuilazi Formation,Linzitou Formation,Xiahuapidianzi Formation and Hentongshan Formation all developed a set of fan-delta front subfacies,bin shallow lake subfacies,deep lake subfacies deposits.Combining the accumulated thickness,distribution range and geochemical characterization of dark mudstones,it is known that the dark mudstones of Houjiatun formation,Yingzuilazi Formation and Xiahuapidianzi Formation are the main source rocks of Hongmiaozi Basin.Various layers reservoir units are mostly belong to special-low porosity,ultra-low porosity,non permeability,ultra-low permeability reservoirs.Mesozoic strata are composed of three assemblages types:self-sourcing and self-reservoiring,lower-sourcing and upper-reservoiring,upper-sourcing and lower-reservoiring.The Hongmiaozi Basin mainly develop four hydrocarbon reservoir types:upward tip-extinguishing reservoir,lenticular sandstone reservoir,volcanic reservoir and ancient buried hill reservoir.The most favorable areas for oil and gas exploration are the lithologic reservoirs of deep concave slope in Hongmiaozi Township and the hydrocarbon reservoir of middle nose uplift.