The Evaluation Of The Lateral And Vertical Fault Sealing Properties In Hydrocarbon Accumulation Period Of Middle And Lower Es3 Member In Daliuquan Area

In order to study the distribution law of hydrocarbon accumulation phases in middle and lower subsection of Es3 in Daliuquan area in Langgu Depression,based on the development of fractures and the distribution characteristics,the relative size of the shale content of fracture filling and the minimum shale content required to seal oil and gas,as well as the relative thickness of the mudstone capping thickness and the minimum breaking thickness needed to seal oil and gas should be utilized,and the lateral and vertical sealability of active fractures were evaluated separately.Therefore,the controlling effect of vertical and lateral sealing of faults on hydrocarbon accumulation in middle and lower Es3 member in Daliuquan area was studied.The results are as follows: 1.The laterally closed fault zone of the middle and lower Es3 member in Daliuquan is mainly distributed in the eastern,southern and northern of Hancun,Caojiawu,Zhongchakou,Liuquan area and Wangju,the area is relatively wide,and the fault-free area is only distributed in the west of Wangju and parts of western Liuquan.The closed area of middle Es3 member is mainly distributed in the eastern and southern parts of the Jiuzhou,Caojiawu and Liuquan areas,and the remaining areas are fault-free areas.2.The vertical closed area of faults in lower Es3 member of Daliuquan is mainly distributed in the southwest of Liuquan area and Zhongchakou,and southeast of Caojiawu area and northern part of Gu'an area,fault-free areas are mainly distributed in the middle of Jiuzhou,Caojiawu and Liuquan areas.The closed area of middle Es3 member is concentrated in the northern part of the Gu'an area and the central and northern parts of the Liuquan area,and the fault-free areas are mainly distributed in the south of Liuquan area,Zhongchakou,Caojiawu and Jiuzhou areas.3.The fault sealing effect on the control of oil and gas is mainly manifested in two aspects:(1)Fault lateral sealing controls hydrocarbon accumulation sites.The oil and gas deposits in the lower Es3 member of the Daliuquan area are mainly distributed in the laterally enclosed traps of the faults of Hancun,Caojiawu,Zhongchakou,Liuquan,and the east,south,and north of the Wangju area,and that in the middle Es3 member of Daliuquan are mainly distributed in the laterally closed traps of the faults of the eastern and southern parts of the Jiuzhou,Caojiawu and Liuquan areas.(2)Fault vertical sealing controls hydrocarbon accumulation strata.In the southwestern part of the Liuquan area,Zhongchakou area and the southeastern part of the Caojiawu area,the oil and gas in lower Es3 member in Daliuquan are mainly distributed under the mudstone caprock and that in the northern part of the Gu'an area,and the central and northern parts of the Liuquan area are mainly distributed under the mudstone caprock of the lower Es3 member,while in the western part of the Wangju and Liuquan faults,the oil and gas are distributed up and down in the mudstone caprock of the lower Es3 member.