麻黄山西区中生界输导体系及成藏模式

Mesozoic Translocating System and Reservoir-forming Mode of Western Mahuangshan

基于野外区调、取心测录井、试油等资料进行麻黄山西区油气藏分布规律分析。认为复杂的断裂背景及前侏罗纪千沟万壑的古地貌使得该区中生界油气输导体系多样化;断裂体系是油气运移的重要输导介质,其有效性与断裂封闭性及时空配置相关,时空配置在西缘冲断带、中央凹陷带、东部凸起带各有不同,根据主干输导介质及其输导路线相应归纳为单一断裂"直排型"、断裂—不整合"烟花状"及断裂—不整合—裂缝"折曲型"输导体系;西缘冲断带以"直排型"输导体系为主,发育断块油藏和断背斜油藏,面积小、油柱高度大;中央凹陷带以"烟花状"输导体系为主,主要为致密低渗岩性油藏,规模小;东部凸起带发育裂隙,以"折曲型"输导体系为主,多为次生油藏,主要为岩性—背斜(鼻状)油藏,油水分异彻底。

In this paper,the oil and gas distribution principle of western Mahuangshan in Ordos Basin is analyzed based on field observation and some data from core,well logging,mud logging and formation test.It' s illustrated that:(1) both complex fracture and pre-Jurassic paleogeomorphic full with ditch and valley make Mesozoic translocating system very diversity;(2) the fracture system is an important translocating media for migration;(3) the validity of fracture system and the sealing of fracture are related to time-space assembly;(3)the assembly is different among the western thrust belt,central depressional belt and eastern bulged belt; (4)there are three translocating systems:single fracture(direct discharging system),fracture-unconformity(fireworks system) and fracture-unconformity-fracture(meandering system);(5) in western thrust belt,the direct discharging system mainly develops,and fault-block and faulted anticline reservoir with small area and high oil column also develops;(6)in central depressional belt,the fireworks system mainly develops,and tight lithological reservoir also develops with small scale;and(7) in eastern bulged belt,the meandering system mainly develops,secondary reservoir also mostly develops,the main reservoir is lithological-anticlinal(nose)reservoir with clear boundary between oil and water.