Study On The Oiliness Of Es₃⁴ Shale In Shichang Subsag,Nanpu Sag

Organic-rich shales are widely developed in the continental basins of eastern China.In recent years,with the increasing emphasis of shale oil resources and the continuous advancement of exploration technologies,the study of shale oil has been paid much attention by scholars abroad,but the characterization of shale oiliness still lacks deeper research.In this paper,taking the shale strata in the fourth part of third member of the Eocene Shahejie Formation(Es₃⁴)in Shichang Subsag of the Nanpu Sag in the Bohai Bay Basin as the research object,the selection and correction of oiliness parameters,the establishment of shale oil resource classification evaluation standards,the construction of oiliness parameter prediction model logging method and other research works are carried out.Combined with the study of lithofacies,the oil content and mobility of the Es₃⁴ shale were evaluated,and the influencing factors of shale oil content were analyzed from from three aspects:hydrocarbon generation,storage and preservation.By correcting the geochemical parameters chloroform asphalt"A"and pyrolysis S₁,the shale oil content of the Es₃⁴ was quantitatively characterized.The light hydrocarbon recovery coefficient of chloroform asphalt"A"is between 1.18 and 1.54.The content of chloroform asphalt"A"after recovery is generally between 0 and 1%,with an average value of 0.2921%.The light recovery coefficient of pyrolysis parameter S₁ is between 1.48 and 1.71,and the recovery coefficient of S₁heavy is between 0.6 and 4.4.S₁ correction model for the Es₃⁴ of the study area has been established;meanwhile,the mobility correction model of the ES₃ member of the 4th member of the Es₃⁴ was obtained by distributed pyrolysis.The shale oil resource classification and evaluation criteria was established according to the relationship between S₁ and TOC divide shale oil in the Es₃⁴ into five categories,which are from Grade I enriched resources(S₁>3 mg/g,S₁/TOC>1)to Grade?ineffective resources(S₁<0.5 mg/g;S₁/TOC<1).The resource potential decreased the oiliness in turn.The?log R log interpretation model and MLP neural network logging model were established to calculate S₁ and TOC,showing good matching with the measured S₁,but the applicability of the?log R model is better.According to the graded evaluation standard,20 wells are finely divided into high-quality single-well layers.In the longitudinal direction,the high-quality layers are mainly located in the middle and lower sections of the Es₃⁴subsection,and the first cycle and the second cycle have obvious are better than the third.In the plane,mobility and oiliness are centered on Gao 11 well area,with S₁ up to 16 mg/g and mobility S₁ up to 7 mg/g.The first cycle overall has the best oiliness and mobility,better than the second and third cycles.The higher the abundance of organic matter,the higher the oiliness display;Type I and Type II₁ organic matter are more oil;Type?₂ and Type III organic matter are less oil;Shale with high brittle mineral content shows a lower oil content.Reservoir that developed pores and microfractures have a dual role in preserving oil and gas,and can play a role in improving oiliness.