Sedimentary Characteristics Of Jiaohe Basin And Its Control Over Petroleum Geological Conditions

Overlying strata in the Weihe Basin are the Early Cretaceous Baojiatun Strata the Moshizizi Formation,the Wulin Strata,and the Naizishan Strata.The basic data of the basin are low,the research is low,and geological understanding is weak.Existing knowledge cannot satisfy the needs of further evaluation of the oil field.In order to study the sedimentary characteristics of Jiaohe basin and the characteristics of its basic petroleum geological conditions,this paper analyzes and summarizes the types and characteristics of sedimentary facies of the basin by comprehensively using regional geological data,geological well cores,and analysis and testing data.in combination with basin simulation technology,the basin is simulated and studied on the history of reservoir formation,and the basin's petroleum geological characteristics are further understood.In this article,by drilling a new well called jiaodi 1 and combining 12 wells in the basin to stratify the basin stratigraphic comparison,the single well phase and plane sedimentary facies distribution in the basin is studied.It is considered that the study area is an alluvial fan— Fan delta-lacustrine facies — Lacustrine facies depositional system,the development of the lake basin in the Jiaonan sag is relatively small,the lake basin is the largest in the Moshizizi Formation,and the Jiaobei depression is larger and smaller,and then shrinks again.It has good consistency with the sequence changes of Jiaodi 1.The distribution and development of the lake basin controls the scope and scale of mudstone settlement.The alluvial fan-fan delta development controls the distribution range of the basin reservoir.Mudstones are developed in all layers of the basin.The mudstones abundance,type and maturity of organic matter are comprehensively evaluated by rock pyrolysis,determination of organic carbon,and determination of vitrinite reflectance.It is clear that there are three sets of source rocks in the Jiaohe Basin,of which the lower part of the Baojiatun Strata is a source rock with a poor source,the lower part of the Moshilazi Strata is a medium source rock,the upper portion of the Wulin Strata develops the best source rock in the whole region;Most of them are Type III and some Type IIB and Type IIA.Source rocks are mostly in the stage of low maturation-maturity.Overall,they have good potential for hydrocarbon generation.Two sedimentation centers of mudstone are developed in the Jiaohe Basin,and the sedimentation center of the mudstone in the Jiaobei Depression is about 500 m thick,which is better than 350 m in the Jiaonan Depression.The three histories revealed that the Jiaohe Basin basically entered the hydrocarbon generation threshold,and the Wulin Strata and the Naizishan Strata were the main source rocks.Combined with the plane,the shale deposits in the center of the basin in the southwestern part of the Jiaohe Basin are thicker.The type of source rock is mostly shale,and the type is good.It has good exploration prospects.