Oil And Gas Enrichment Characteristics Of Es₁^x In Lixian Slop-Suning Subsag Of Raoyang Sag,Jizhong Depression

The Lixian slop-Suning subsag is located in north-central of the Raoyang sag.The Lixian slope is one of the important slopes in the Raoyang sag.The Suning subsag has been proven as an important exploration area.Due to the complicated geological and oil distribution in the study area,further exploitation work is restricted.Therefore,To reveal the factors that affect the accumulation of oil and summarize the oil accumulation pattern,a series of researches on the characteristics of source rocks,reservoirs,formation pressure and structure are carried out in the study area.Based on the qualitative and quantitative evaluation of source rocks,the types of organic matter,abundance and maturity of,the development range of hydrocarbon source rocks and the amount of hydrocarbon generation were confirmed.Based on the research of sedimentary petrology,single well facies,continuous well facies and plane facies,the reservoir development position,physical properties and oil-bearing characteristics were summarized by combining the oil test results and physical properties of various reservoirs and facies.Using the acoustic logging data to calculate the formation pressure of the source rock,we got the longitudinal,section and plane distribution characteristics of the formation pressure in the study area.Finally,according to the reservoir distribution characteristics,pressure plane distribution,faults and tectonic distribution in the study area,the oil accumulation rules under the above factors were obtained and the oil enrichment patterns were summarized.The organic matter abundance of the source rock in the Es₁^x Formation of the study area is moderately low,with Type ?₁ kerogen as the dominant source,and most of them belong to the un-matured-low-mature source rock,with a total oil production and gas generation of34.1×10⁸t and 18.25×10¹¹m³ respectively.The source rock of the study area determined the approximate scope of the reservoir.The braided river delta underwater distributary channel and the shore shallow lake sandy beach are favorable reservoirs.The main rock types in the study area are feldspar sandstone and lithic feldspar.Sandstone and limestone,compaction and cementation are the main factors of reservoir porosity loss.The dissolution can improve the physical properties of the reservoir.The Oily of all types of reservoirs is oil spots mostly,followed by oil immersion.The formation pressure is composed of large segments of hydrocarbons.Upward and downward from the center of large section of source rocks,there are an overpressure zone,a weak overpressure zone,and an atmospheric pressure zone.Each pressure zone is distributed around the center of the overpressure zone.The pressure from the subsag to the slope zone is reduced,the area is reduced.Vertically oil and gas in the subsag and slopes is distributed in the weak overpressure zone and the tail sandstone mostly,which is the result of the downward filling of oil and gas under overpressure.The structural highs are conducive to the accumulation of oil and gas.The horizontally fault company source rock and reservoir longitudinally,adjusting the hydrocarbon distribution.Fault nose reservoirs and fault block reservoirs are developed in outer band and steep slopes mostly.The lithologic lens body reservoirs and fault reservoirs are mostly developed in inner slope and Suning subsag.