夏口断层封闭性及东西段封堵能力差异

Fault sealing and difference between the east section and the west section of Xiakou fault

针对夏口断层的不同部位、不同层位封闭性不同,其西部、东部封闭性较好,中部侧向封闭性较差的问题,指出了对接盘物性、泥岩涂抹系数、断面正压力及泥地比等的差异性导致了夏口断层的封闭性差异:1)通过夏口断层不同部位对接盘岩性对比,认为夏口断层西部和东部与物性较差地层对接,断层封闭性较好,形成夏52、夏32油藏,中部与物性较好地层对接,断层封闭性较差;2)通过夏口断层泥岩涂抹系数计算,分析其不同部位的侧向封闭性,西部和东部泥岩涂抹系数较小、断层封闭性较好,深部泥岩涂抹系数较大、断层侧向封闭性较差;3)通过计算断面正压力来衡量断面的紧闭程度,除个别岩层外,夏口断层所受断面正压力较大,其垂向封闭性较好;4)通过断层结构面和产状的差异,分析其对夏口断层封闭性的影响;5)结合夏口断层不同部位的断层生长指数,通过夏口断层活动时期与油气运移时期的配置关系,探讨了夏口断层封闭性东西段差异。

In view of different sealing properties in different parts and layers of Xiakou fault,namely,there is a good fault sealing in eastern and western parts,while a poor lateral sealing property in central part of the fault.Therefore,it is proposed that the lithological differences in the parts of the fault docking sides,the mudstone daubing coefficient,the normal pressure of the fault surface,the mud ratio and so on lead to the sealing differences from west to east sections of Xiakou fault.1)By comparing the li-thological differences in the parts of the fault docking sides,it is found that Xiakou fault docks with the stratums of inferior physi-cal properties in western and eastern parts of the fault,which leads to a good sealing property of the fault and forms Xia 52 and Xia 32 oil reservoirs.While the central part docks with the stratums of good physical properties,resulting in the poor sealing property of the fault.2)By calculating the mudstone daubing coefficient of Xiakou fault to analyze the lateral sealing property in different parts of Xiakou fault,the mudstone daubing coefficient in western and eastern parts is lower than that in deep mudstone, indicating that the sealing ability of the former is better than that of the latter.3)By calculating the normal pressure of the fault surface to measure the closed degree of fault fracture,it is found that the normal pressure of the fault surface is relatively large except some individual faults,and the vertical sealing ability of the fault is good.4)The effects of the differences between fault structure planes and fault occurrences on the sealing properties of Xiakou fault are analyzed.5)The differences of sealing proper-ty from west to east of Xiakou fault is discussed by analyzing the matching relationship between the activity period of Xiakou fault and the migration period of the oil and gas,as well as the fault growth index in different parts of Xiakou fault.