Characteristics And Resource Evaluation Of Oil Shale In The Lower Cretaceous Jiufotang Formation In Wujiazi Area Of Jianchang Basin

Jianchang basin is rich in oil shale resources,located in the western Liaoning province,and its oil shale sequences are mainly located in the lower Cretaceous Jiufotang formation.This time,a systematic study of oil shale rock series in the Wujiazi area of Jianchang basin was carried out to reveal the characteristics of the oil shale and the oil shale distribution pattern and resource potential in the research area.The Jiufotang Formation in the research area has developed 3 oil shale ore groups,totaling 10 oil shales.Oil shale is grayish black-brown-black,thin-middle and usually has horizontal bedding and deformation bedding.The oil shale mineralization rate tends to decrease from lower to higher and then decrease.The oil content of the first layer of the Midding group 1 is the highest,with an average oil content of 5.68%and a maximum of 7.04%.It has high-ash,medium-high calorific,and low-to-ultra-low-sulfur medium-low oil shale.The types of kerogen in oil shale were mainly type I and type II₁,among which there were more type I in the Midding group 1 and II₁ types in the Midding group 2.The maturity was in the immature and low-mature stages.In the research area,the Jiufotang Formation developed three types of sedimentary facies:lake facies,fan delta facies,and sublacustrine facies,and further divided 7 subfacies and 9 microfacies.In combination with the field and borehole data of this area,there are a total of 3 third-order sequences,of which the sequence III low system tract?LST?develops fan delta plain deposits in the northeastern part of the research area and the south,and the fan delta front is in the entire eastern part.There are distributions.Shore-shallow lake deposits are distributed in the central and northeastern part of the research area.The TST develops fan delta plain subfacies in the northeast and southwest,and the fan delta frontal subfacies develop in the southern boundary.Developed deep lake-hemi-deep lake sedimentary facies;high system tract?HST?developed deep-half-deep lakes and gravity flow sublacustrine fan facies,with gravity flow subfacies mainly distributed in the southeastern part of the research area,with a wide range of distribution.The transition to the northwest direction is deep lake-hemi-deep,with thick oil shale developed.The oil shale planes in the research area are distributed as strips in the middle of the research area.Among them,seven oil shales are developed in sequence III and the oil shale can reach a maximum thickness of 28m.All of them are developed in the deep-semi-deep lakes of the high system tract.In the sedimentary phase.The thickness and distribution scale were the best in the oil shale in the Midding group1,the second in the Midding group 2,and the depth of the oil shale floor in the range of 18 to 411.96m,which was in line with the industrial mining index.The volume method was used to evaluate the resources of Wujiazi in Lingyuan,Sanjiazi in Lingyuan,Jiufotang in Kazuo,Wenzhangzi in Kazuo 4 exploration areas and Lingyuan prediction area.The resource evaluation results show that the oil shale resources in Lingyuan area are 10902930 thousand tons and oil shale oil resources are 473200 thousand tons,including 324150 thousand tons of oil shale resources in Wujiazi exploration areas,14880 thousand tons of oil shale oil;147510 thousand tons in Sanjiazi exploration area,5430 thousand tons of oil shale oil;andthe oil shale of Wenzhangzi exploration area is27360 thousand tons,equivalent to 1160 thousand tons of oil shale oil resources;Jiufotang exploration area17680 thousand tons of oil shale resources,equivalent to 970 thousand tons of oil shale oil resources.Lingyuan predicted that oil shale resources will be 10386230 thousand tons,equivalent to 450760 thousand tons of oil shale oil.