Shale Oil And The Key Parameters For Evaluation The Resources Developed In The Second Member Of Kongdian Formation In Cangdong Sag,Bohai Bay Basin,Northeast China

The shale oil exploration in North America has achieved great success and has a a major impact on the world energy supply.China's shale oil resources are abundant.The second member of Kongdian formation?Ek₂?in Cangdong Sag in Bohai Bay is a hot spot for shale oil exploration in China.In order to further clarify the shale oil enrichment conditions and resource potential of Ek₂ in Cangdong sag of the Bohai Bay Basin,based on logging data,geochemical data,and casting thin sections,geochemical methods and logging analysis methods are used to analyze key parameters such as oil content and mobility of Ek₂.The shale oil resource in the study area was estimated by the small panel volume method.The organic-rich mud shale of Ek₂ in the Cangdong sag is located in the oil-producing window.The sediment thickness is between 250?500m.The thickness of the source rock is more than 40m.The organic matter is mainly type I-II₁,and the organic matter is abundant.The TOC is mainly in the range of 1.2%?6%.The S₁+S₂ is mainly between 0.059mg/g and 104.38mg/g,and the maturity is high,mostly vitrinite reflectance?Ro?is greater than 1%.It has a good hydrocarbon generation potential and is a good layer of potential for shale oil.The Ek₂is a low-porosity and low-permeability reservoir.The porosity is mainly between 5%and 10%,and the permeability is mainly between0.01 and 0.42 md.The reservoir space are mainly micro-crack and intergranular dissolved pores.The shale oil content of the study area was quantitatively characterized by the chloroform asphalt�A�and the pyrolysis parameter S₁.Due to the experimental relationship,the chloroform asphalt�A�and the pyrolysis parameter S1 were corrected by geochemical methods.The light hydrocarbon recovery coefficients for�A�and S₁ is 1to 1.56,which increases with the increase of maturity.The recovery coefficient of heavy hydrocarbons is 1.8?14.13,which decreases with the increasing of maturity.The?Log R model of KN9 well was used to predict S₁ and TOC by well logging analysis.The predicted values were well matched with the measured S₁and TOC.The OSI index was used to quantitatively characterize the shale mobility in the study area,with an OSI index>75 mg/g accounting for 19%.The factors affecting the shale mobility in the study area?S₁,viscosity,clay,minerals?were analyzed.The comprehensive analysis showed that the overall mobility of the second member of Ek₂ was generally observed.The calculation methods of shale oil resources at home and abroad have been extensively investigated,and the advantages and disadvantages of each method are compared and analyzed.According to the exploration degree of the Cangdong sag,the shale oil resource of Ek₂in Cangdong sag is calculated by the small-face volume method.The calculation results show that the total resource of Ek₂in Cangdong sag is 19.06�10⁸t.The amount of recoverable resources is 2.859�10⁸t,and the amount of resources in the shale is 15.38�10⁸t,and the amount of resources in the dense interlayer is 3.68�10⁸t.According to the�three-point�relationship between the pyrolysis parameters S₁ and TOC and between the chloroform asphalt�A�and TOC,the study area resources is classified according to the degree of enrichment,and is divided into enriched resources,ineffective resources,and low-level resources.The resources at each level are:10.51�10⁸t,3.14�10⁸t,0.95�10⁸t.Using the principle of material balance,the amount of movable resources in the study area was 3.72�10⁸t,Which provide a basis for subsequent exploration.