【作者】 过敏；

【导师】 沈忠民； 李仲东；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2010， 博士

【摘要】 针对鄂尔多斯盆地上古生界低孔、低渗、低压、低丰度、大面积分布的岩性致密气藏的特点,在总结分析前人已有的研究成果基础上,运用石油地质学、成藏动力学、压力封存箱理论、含油气系统等最新理论和分析测试手段,选取鄂尔多斯盆地北部大牛地气田和杭锦旗地区上古生界压力分布、成因、成藏组合、压力封存箱内幕结构、地层水特征、岩性圈闭成藏过程有效性及天然气成藏机理等进行了研究,取得的主要成果如下:(1)通过对大牛地、杭锦旗地区上古生界气藏地层压力分布规律的研究,认为大牛地气田上古生界气藏主要属于常压-低压气藏,杭锦旗地区上古生界气藏属于低压气藏。大牛地上古生界异常低压成因主要为构造抬升引起的温度下降和孔隙反弹、天然气的散失,经计算温度下降可以引起压力下降约33%;杭锦旗上古生界由于侧向封闭条件不好,异常低压成因主要为天然气的扩散泄漏。(2)首次发现杭锦旗地区上古生界存在混合成因的地层水。通过分析断裂带地层水Mg2+离子富集来源、pH值偏低异常、矿化度高异常、地温梯度高异常情况及Caexcess与Nadeficit相关关系证明是泊尔江海子基底大断裂活动促使深部富Mg2+离子、偏酸性的热流体上涌与上古地层水混合作用,从而有利于烃源岩的成熟,有利于储层次生孔隙的形成,是油气有利运移聚集区。(3)根据上古生界过剩压力的发育形态,把大牛地气田过剩压力归类为Ⅰ类单峰渐变型、Ⅱ类双峰渐变型、Ⅲ类单、双峰突变型三种类型,分析了不同类型与产气性的关系。(4)根据烃源岩对比、天然气成藏示踪、输导体系(砂体、裂缝及组合)及与烃源岩配置关系、运移动力等建立了大牛地气田上古生界天然气运移聚集模式图。近源成藏组合以砂体+裂缝输导,在盒2+3段形成天然气聚集区;源内成藏组合以砂体为主要输导,形成天然气聚集区。若源内成藏组合裂缝发育,使得天然气纵向向上逸散,形成天然气逸散区,导致圈闭中甲烷含量降低,天然气逸散同时储层测试表现为含水气层、含气水层和气水同层。并建立了不同成藏组合的天然气充注模式。研究区远源成藏组合发育在杭锦旗地区,运移动力主要为浮力,天然气充注方式为浮力流;近源、源内成藏组合天然气运移动力主要为源储剩余压差,天然气充注方式主要为“活塞式”,致密背景下的优质储层浮力起一定作用,甚至在优质储层达到一定连续分布可以在构造低部位形成局部边底水。致密气藏背景下浮力起一定作用区为致密气藏“甜点”。(5)根据成藏动力的有效性、输导条件的有效性及封闭条件的有效性研究建立了上古生界天然气成藏过程有效性评价体系。大牛地上古生界岩性圈闭成藏过程的有效性评价为:在上石盒子组区域盖层的物性+压力封闭的双重封闭条件下,天然气只能在其以下层位成藏,近源成藏组合盒2+3段岩性圈闭成藏过程有效性主要受成藏动力的有效性和输导条件的有效性控制;源内成藏组合岩性圈闭成藏过程有效性主要受局部封盖条件的有效性和输导条件的有效性控制。杭锦旗地区上古生界由于断裂、不整合面、砂体发育,保存条件差,其成藏过程有效性主要受封闭条件的有效性控制。上古生天然气成藏过程有效性的评价体系的建立为下一步寻找天然气有利富集区提供了优选条件,具有重要的理论和现实意义。(6)大牛地气田上古生界天然气富集规律主要受生气强度、区域封盖条件、封存箱内幕结构、运移动力及输导体系控制:区域盖层控制了油气只能在箱内成藏,生气强度控制了主力产层的分布范围,压力封存箱的内幕结构影响了产气层位及含气性,运移动力影响了天然气的富集程度,输导体系控制了天然气成藏层位和富集程度,浮力起一定作用区为致密气藏高产富集区。并建立了大牛地气田上古生界封存箱型成藏动力学模式。(7)杭锦旗断裂南部是近源低丰度岩性成藏模式,圈闭是控制成藏的最主要因素,有利层位为盒1段、山西组;断裂以北是远源构造—岩性成藏模式,盒1段为“泄流带”,盒1段要成藏,只能在其泄流带的低势区(局部构造)成藏。裂缝和小断裂的发育改善了盒2、盒3段聚集成藏,有利层位为下石盒子组,特别是盒2、盒3,规模比盒1段大,有利区为什股壕地区。更多还原

【Abstract】 With an emphasis on Upper Paleozoic in the Ordos Basin which has low porosity, low permeability, low pressure, low abundance, and large-scale distribution of lithologic and tight gas reservoir features. On the basis of summing up and analyzing the results of previous studies, this paper applied the latest theories which include petroleum geology, Pool-forming dynamic, pressure compartment, petroleum system, etc. and analysis-test tools. Studied Daniudi gas field in north of Ordos Basin and Hangjinqi area, the study include pressure distribution, pressure causes, accumulation in combination, inside structure of pressure compartment, formation water characteristics, the effectiveness of accumulation process with lithologic trap, and mechanism of gas accumulation. Finally, the main results obtained are as follows:(1) Through research on formation pressure distribution in the Daniudi gas field and Hangjinqi area, we thought that gas reservoirs in the Upper Paleozoic of Daniudi gas field were mainly atmospheric pressure - low pressure gas reservoir, and Upper Paleozoic of Hangjinqi were belongs to low-pressure gas reservoir. The cause of subnormal pressure in the Upper Paleozoic of Daniudi gas field mainly was tectonic uplift, which caused temperature drop, porosity rebound and gas loss. The temperature drop can cause the pressure drop of about 33% after calculated. Due to the lateral closed condition as well, the cause of subnormal pressure was the spread of gas leakage in the Upper Paleozoic of Hangjinqi area.(2) First discovered the existence of hybrid origin formation water in the Upper Paleozoic of Hangjinqi area. Through analyzed the source of Mg2+ enrichment, PH was low abnormal, salinity was high abnormal, geothermal gradient was high abnormal and Caexcess relationship with Nadeficit in fault zone proved that hybrid origin formation water was formed by the mixture of Nepal Jiang Haizi basement fault activity to promote deep rich Mg2+ , acidic fluid upwelling of hot water and Upper Paleozoic formation water. Such hybrid process was conducive to the maturity of source rocks, and the formation of secondary pores. This area was the favorable oil and gas accumulation zone.(3) According to the form of excess pressure in the Upper Paleozoic of Daniudi gas field, we classified the excess pressure into three types. TypeⅠhad one gradual change peak, typeⅡhad two gradual change peak, typeⅢhad one or two abrupt change peak. Then we analyzed the relationship between different types and accumulation of natural gas.(4) According to the contrast of hydrocarbon source rock, tracer of gas accumulation, transporting system , migration agent and the relationship of configuration about hydrocarbon source rocks etc, then we established model map of gas migration and accumulation in the Upper Paleozoic in Daniudi gas field. Proximal plays through the fracture and the sand’s joint transportings, had accumulaited natural gas in He2 and He3. Within the source plays through the sand’s transpotings formed gas accumulation areas. Within the source plays the development of high-angle fracture in sandstone cause the gas vertical disperse and form the gas dispersion area, which leads to decrease the content of methane in traps, the text of reservoir where gas disperse showed water gas formation, gas water formation and gas-water-bearing formation. We established different filling mode of natural gas plays in the Upper Paleozoic in Ordos Basin. Distal plays developed in Hangjinqi area, its main migration agent was buoyance, and the charging mode of distal plays is buoyant flow. Proximal plays and within the source plays’main migration agent were the difference of overpressure, there means of natural accumulation were“piston type”, in the high-quality reservoirs of dense background buoyancy plays a important role, even the high-quality reservoir reaches a certain continuous distribution where could form local edge and bottom water in the low construction position. The context of tight gas reservoirs where buoyancy plays important role called as“dessert”.(5) This paper evaluated the validity of the process of natural gas accumulation in the Upper Paleozoic by evaluating the effectiveness of dynamics, transporting condition and closed condition. By evaluate the process of accumulation of lithologic traps in the Upper Paleozoic in Daniudi area, we thought that: In the dual closing conditions of regional physical properties and pressure seal, natural gas only accumulated under it, the controlling factors of the validity of accumulation process in lithologic traps in He2+3 which were proximal play was the validity of dynamics and transporting conditions; the controlling factors of the validity of accumulation process in lithologic traps which were within norce plays was the validity of part sealing gland condition and transporting condition. In Hangjinqi area, the validity of accumulation process ctrolled by closed conditions because of the development of fault, unconformable surface, sand’s development, bad conservation. We established evaluste system for the validity of natural gas accumulation process in the Upper Paleozoic for further evaluation and search for natural gas rich region conducive to providing optimal conditions, has important theoretical and practical significance.(6) Gas accumulation of Upper Paleozoic in Daniudi area is mainly dominated by the gas generation intensity, conditions of regional sealing glands, pressure compartment inside the structure, migration agent and transporting system. The gas generation intensity control the distribution range of the main producing formation, pressure compartment inside the structure affected the gas producing formation and gas bearing, migration agent influenced the enrichment intensity of natural gas, transporting system controlled accumulation formations and the enrichment intensity of natural gas, the tight gas reservoirs where buoyancy plays a important role are high-yield rich regions. Then we established the model of compartment Pool-forming dynamics in the Upper Paleozoic in Daniudi area.(7) The model of the southern fault of Hangjinqi is low abundance lithologic proximal accumulation, trap was the most important factor in controlling accumulation, and the favorable reservoirs were He1 and Shanxi formations. The model of the north of the fault was distal tectonic—lithologic accumulation, He1 was“zone of discharge”, only in the low potential zone it could accumulate. The development of fracture and small fault improved the accumulation conditions of He2 and He3, the favorable reservoir was lower Shihezi formation, especially He2 and He3, the scale of them were bigger than He1, the favorable area was Shiguhao area.更多还原