Evalution Of Movable Oil And Retention Machanics Of Dongying Depression Shales

The subject of this dissertation is focus on the movable oil of shales and the relationship between oil and source rocks during the process of oil generation and retention in Dongying Depression.Consequently the pyrolysis and retention experiments were carried on the Es₃³ Wang 57 and Es₄¹ Wang 161 samples,respectively.On the basis of the pyrolysis experiment,the composition of kerogen pyrolysis products and yields were analyzed.Moreover,the kinetic software was used to simulate the products.Combined with the burial history and heating history of Dongying Depression,the hydrocarbon generation history and hydrocarbon retention history of the lower member of the third Shahejie Formation and upper member of the fourth Shahejie Formation were obtained.The analysis results of kerogen pyrolysis experimental products showed that,for the comparison of Wang 57 and Wang 161 kerogen,the total hydrocarbon yields both increase first and then decrease with the increase of pyrolysis temperature,the yield of C₁-C₅ gas increases with the increase of pyrolysis temperature,both the yield of C₆-C₁₄light hydrocarbons and C₁₄₊heavy hydrocarbons increase with the increase of pyrolysis temperature.This is because the heavy components generated by kerogen decompose into light components,leading to the gaseous hydrocarbons yields continuous increase and C₆-C₁₄ light hydrocarbons first increase and then decline,in addition,the turning point of yield of heavy hydrocarbons appears later.Two kerogens,Wang 57 and Wang161,were studied by kinetics.The results showed that the Wang 57 source rock is now entering the main stage of hydrocarbon generation,while the Wang 161 source rock has entered the later stage of hydrocarbon generation.Hydrocarbon retention experiments were carried out on Wang 57 and Wang 161 kerogen,respectively.Five different solvents,the solubility parameters within 7-13(cal/cm³)^0.5,were used to carry out swelling experiment to obtain the swelling curves according to the range of kerogen solubility parameters,which were used to simulate the retention of shale oil in residual kerogen at different maturity levels.The experimental results showed that the absorption capacity of kerogen to organic solvents decreases,and the absorption capacity gradually balance with the increase of maturity.Because the structure of kerogen gradually becomes stable,and part of shale oil is difficult to be discharged from kerogen with the increase of kerogen thermal evolution.Five crude oil samples with different concentrations were prepared from Well Fanye1 for the surface adsorption experiments,and the maximum oil adsorption capacity of clay minerals,quartz/feldspar and calcite minerals were obtained,respectively.The results showed that the maximum oil adsorption capacity of clay minerals,quartz/feldspar and calcite minerals is 18 mg/g,3 mg/g and 1.8 mg/g,respectively.The total organic carbon and mineral contents of the lower member of the third Shahejie Formation and upper member of the fourth Shahejie Formation in Dongying depression were obtained by statistics.The mass of crude oil adsorbed on the surface of inorganic minerals in source rock was calculated by the formula.Although extracted Chloroform asphalt"A"is not often used as an evaluation index in shale oil evaluation,extracted chloroform asphalt"A"is more similar to shale oil in both compositions and chemical properties.Based on the variation of porosity,gas-oil ratio,rock adsorption capacity and reservoir parameters with maturity,combined with the dynamics of hydrocarbon generation and retention,a moblie model of shale oil was established.This helps to identify potential shale reservoirs and evaluate movable shale oil resources.The model shows that the maturity range of high quality shale oil resources in Dongying Depression is between 0.7-1.0%Ro.When the maturity is less than 0.7%Ro,there is a small amount of oil migrated to Dongying Depression.When the maturity is more than 1.0%Ro,the amount of oil being expelled from source rocks increases,but may enter conventional reservoirs rather than shales.The infrared spectrum analysis of residual kerogen showed that the content of aliphatic compounds in kerogen decreases,the degree of aromatization increases the degree of condensation of kerogen increases gradually.In addition,the content of oxygen-containing functional groups decreases during the process of hydrocarbon generation.In the absence of the oil window,the hydrocarbon generation potential of kerogen increases with the maturity of kerogen.After the oil window,although kerogen has hydrocarbon generation potential,its hydrocarbon generation potential will be greatly reduced.Moreover,in the process of hydrocarbon generation,the degree of thermal evolution of kerogen also increases gradually.