【作者】 李兴文；

【导师】 李仲东；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2010， 硕士

【摘要】 已有的勘探成果表明,鄂尔多斯盆地南部镇泾地区中生界具有丰富的油气资源,油藏具有上生下储和下生上储的成藏特征。前人对该区研究多集中在生、储、盖层等成藏基本条件的研究,对成藏规律缺乏系统的认识。为了进一步明确鄂尔多斯盆地镇泾区块中生界油气分布及成藏规律,本文通过泥岩压实研究中生界过剩压力特征及其与油气的关系,对已知中生界岩性—构造油气藏的解剖,结合研究区基本成藏地质条件的综合分析,加深对中生界油气成藏特点与规律的客观认识,为进一步寻找该地区油气分布规律提供坚实的地质依据。泥岩压实研究表明,代家坪和川口地区延长组欠压实段主要出现在长7底部,而何家坪地区延长组欠压实则从长7中部开始出现。总体来讲,镇泾地区欠压实段比较分散,与西峰油田延长组欠压实段有明显的差别。研究区中生界过剩压力主要发育突变型和渐变型两种压力结构,厚层泥岩连续发育的地方主要以突变型压力结构为主,而泥岩不连续发育的地方则以渐变型压力结构为主。镇泾地区中生界烃源岩发育,长7主力烃源岩以Ⅱ2型干酪根为主,Ⅱ1型干酪含量较少。野外剖面、取芯资料及测井资料表明,长8和长6以三角洲前缘沉积为主,骨架砂体为三角洲前缘的水下分流河道,而长7主要以湖相沉积为主,在区块的西侧发育有三角洲沉积,而在区块内有滑塌的浊积岩。在大量薄片鉴定的基础上,结合埋藏史,将中生界砂岩的成岩作用划分为三种类型:持续埋藏型成岩系统(长8及部分长6),中间开启型成岩系统(部分长6)和长期浅埋开启型成岩系统(延安组)。不同成岩作用下形成的储层,具有不同的储集物性,油气二次运移的动力也有所不同。长8段由于紧邻优质烃源岩,在异常压力驱动下,油气向下直接进入储集层,进入储集层的油气由于排驱压力高而没有进行明显的侧向运移;至于长6段油藏,烃源岩生成的油气在异常压力作用下通过裂缝向上进入储集层中,对于物性好的储层,有可能发生侧向运移,在构造和储集物性适宜的条件下聚集成藏,大部分致密储层并没有发生长距离的侧向运移。延安组油藏主要为次生油藏,油气在河道砂岩中靠浮力驱动,发生长距离的侧向运移和垂向运移,在构造高部位聚集成藏。根据镇泾地区中生界地层异常压力的分布,油藏形成条件和系统的封闭性,将延长组—延安组油藏成藏动力学系统划分为3种类型:高压它源源封闭成藏动力子系统、高压自源封闭—半封闭成藏动力子系统和常压它源开放—半封闭成藏动力子系统。对于高压它源源封闭油藏,由于储层致密,油气运移动力不足,为典型的成岩圈闭,油藏的形成主要受控于储层,勘探的重点为寻找高效储层及裂缝发育带;对于高压自源封闭—半封闭油藏,受大气淡水淋滤改造的储层是勘探的重点,这部分储层主要发育在前侏罗纪古地貌斜坡处中,古地貌斜坡是勘探的重点;常压它源开放—半封闭油藏的勘探重点是圈闭问题,古地貌转折处或河道砂岩发育处,易受差异压实作用形成圈闭。更多还原

【Abstract】 Mesozoic Formation has rich oil and gas resources, according to the existing exploration achievements in Zhenjing area, Ordos Basin. Accumulation characteristics, the reservoir is born, laying on the reservoir characteristics of reservoir accumulation.Previous studies were focused on the area, reservoir, seal and other basic conditions of accumulation, on the lack of a systematic accumulation of knowledge rules. In In order to further clarify Mesozoic Formation distribution and accumulation of oil in Zhenjing area,Ordos Basin.This study by mudstone compaction, To study the characteristics of the excess pressure and the relationship between excess pressure and oil, Analyze typical reservoir, Combination of the basic study area forming a comprehensive analysis of geological conditions,understanding of the Mesozoic oil and gas accumulation characteristics and objective understanding of the law, Further search for oil and gas distribution in the region to provide a solid geological foundation.Mudstone compaction research shows that Uncompacted shale section at the bottom of the Chang- 7 member of yanchang formation in Daijiaping and Chuankou area ,but in Hejiaping area ,uncompacted shale section at the bottom of the Chang- 7 member of yanchang formation.In general, uncompacted paragraph rather scattered in Zhenjing region, and to extend the group of Xifeng Oilfield segment undercompaction significant difference.Excess pressure in the main study area and the gradual development of mutations in two pressure-type structure, thick layer of mud where a continuous development of mainly mutant mainly mudstone continuous development of the space is not graded based.Hydrocarbon source rocks in the area was developed, the Chang- 7 member of yanchang formation main source rock in the main kerogen typeⅡ2, contains a small amount of typeⅡ1.Outcrops, core data and logging data show that the Chang- 7 and chang -8 member of yanchang formation mainly develope delta front deposits , Sand comes from underwater distributary channel,the Chang- 7 member of yanchang formation mainly deposits lacustrine in the development of a block west delta, founding turbidite deposition in study areas. In a large number of slices and based on the combination of burial history, the Mesozoic Sandstone is divided into three types: Continuous buried type of diagenetic system (the Chang- 8 member of yanchang formation and part of the Chang- 6 member of yanchang formation), Intermediate open diagenetic system type (part of the Chang- 6 member of yanchang formation), and Long-term open-type shallow diagenetic system (Yan’an formation). Formed under different reservoir diagenesis, have different reservoir properties and oil and gas secondary migration of power is also different.The Chang- 8 member of yanchang formation close to high-quality long as source rocks, in the abnormal pressure driven down oil and gas directly into the reservoir, oil and gas into the reservoir high displacement pressure as no significant lateral migration.As long Chang- 6 member of yanchang reservoirs, source rocks generated oil and gas under pressure in the abnormal upward through cracks into the reservoir;For good reservoir properties, lateral migration may occur in the structure and reservoir property suitable accumulation conditions,most of the dense reservoir and no long-distance lateral migration,Yan’an Formation Reservoir mainly secondary reservoir, oil and gas in sandstone in the buoyancy-driven by long-distance lateral migration occurs, structural high position in the accumulation.According Zhenjing overpressure distribution in stratigraphy, diagenesis, reservoir formation conditions and the system closed, will extend the group - Yan’an Formation Reservoir accumulation mechanism is divided into 3 types:Closed high-pressure source petroleum migration and accumulation dynamic subsystem,High Pressure-Pressure reservoir closed mixed source petroleum migration and accumulation dynamic subsystem, Pressure from the source closed - semi-closed petroleum migration and accumulation dynamic subsystem, Pressure is open source - a semi-enclosed reservoir petroleum migration and accumulation dynamic subsystem. Closed high-pressure source petroleum migration and accumulation dynamic subsystem, due to tight reservoirs, oil and gas migration motivation enough for the typical diagenetic trap, reservoir formation is mainly controlled by the reservoir, the focus of exploration and the search for efficient reservoir cracks Development zone;For the high pressure from the source closed - semi-closed reservoir by atmospheric reservoir of fresh water leaching transformation is the focus of exploration, this part of the Jurassic reservoirs are developed in the former slopes Office of ancient landscapes, ancient landscape of slopes is the focus of exploration;Pressure is open source - a semi-enclosed reservoir exploration focus trap problem, or a river bend in the ancient sandstone landform development office, vulnerable to the formation of trap differential compaction.更多还原