Oil And Gas Resources Evaluation Of Chaluhe Fault Depression In Yitong Basin

Chaluhe fault depression is located in the northeast of Yitong basin, which has the largest quantity of oil and gas. From the west to the east, the depression is divided into two forts:Xinanpu sag and Botai sag. In order to estimate the oil and gas resource potential of the fault depression, from the perspective of the causes of oil and gas generation, migration and accumulation, with the help of chemical power method, calculating the amount of hydrocarbon generation of source rock in organic matter, and aggregation coefficient determined by hydrocarbon expulsion coefficient. Finally, calculating the total quantity of hydrocarbon resources and analyzing the distribution of oil and gas resources in the study area.First of all, by collecting the data of drilling, well logging and geochemical analysis,evaluating qualitative of source rock from the aspects of organic matter abundance, type and maturity. Then based on the theory of late hydrocarbon generation of kerogen with thermal degradation, the selection of main hydrocarbon generation layer core sample, under the condition of rapidly increasing heat in laboratory, simulating the process of hydrocarbon generation of organic matter in source rock, and then redefining computational chemistry kinetic parameters combined with the burial history and thermal history reconstruction model to calculate the amount hydrocarbon generation of organic matter in source rock in each layer.Finally,the quantity of hydrocarbon generation is multiplied by the coefficient of hydrocarbon expulsion and accumulation coefficients, and thus calculating the total oil and gas resources in the sag. For the further oil and gas exploration, with the help of the guidance of optimization calculation results, the grid approximation method is adopted for oil and gas resources in the plane distribution.The results show that the Shuangyang group mudstone has high quantity of organic matter, good types and high maturity, the Sheling group mudstone takes second place, Yongyi is the worst group.The thermal gradient of Xinanpu sag between the end of Sheling group and the beginning of Yongji group starts to rise. While the thermal gradient of Botai sag keeps declining until Qijia group. The thermal gradient of both sags floats between 3℃/100 m and4.5℃/100 m. The calculation results of Chaluhe fault depression show that the main oil-producing bed in Xinanpu sag is shuangyang, the Sheyi and Yonger group, while the main oil-producing bed in Botai sag is Shuangyang, Sheling, Yongyi and Yonger group. The maingas-producing layer in Xinanpu sag is Shuangyang, Sheyi and Yonger group, while the main gas-producing layer in Botai sag is Shuangyang, Sheling, Yongyi and Yonger group. Besides,Xinanpu sag produces larger quantity of gas than Botai sag. Overall, Chaluhe fault is given priority to gas.Finally, oil and natural gas resources evaluation results show that compared with the former three times evaluation, this evaluation has nearly 4 times higher oil resource and 30 times higher natural gas resources, which means that the fault still has the great exploration potential. With the help of studying the potential amount of oil and gas resource, the results will provide powerful basis for investment decision makers to plan the exploration of the depression.