【作者】 刘岩；

【导师】 张哨楠；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 天然裂缝是油气藏中普遍存在的一种构造现象，尤其在盆地构造活动强烈的区域。对于低渗砂岩油藏，断裂系统对油气的成藏以及后续的开发工作显得尤为重要。本文研究的鄂尔多斯盆地南部红河油田长8油藏通过多年的勘探和开发实践已经证明了断层及裂缝系统是该油藏油气富集和获得高产的关键。本论文针对红河油田裂缝系统特征、成因、期次、发育控制因素以及和油气富集之间的关系展开深入研究，搞清红河油田长8油藏断裂系统的分布规律、油气成藏条件及断裂控油作用，进而构建油气成藏模式。文中根据大量野外露头裂缝的调查、岩芯裂缝描述、成像测井裂缝特征的研究，总结了裂缝的基本特征，认为研究区主要以高角度和垂直裂缝为主，主要发育北东组系，其次为北西组系，纵向可贯穿不同岩性层段，横向发育规模可以达到数米到十余米；研究区目的层段同时发育剪性破裂和张性破裂，其中剪性破裂缝面可见不同方向的剪切擦痕或者缝面光滑平整，呈共轭组系出现；而张性破裂缝面粗糙、凹凸不平、呈弯曲状等特征，缝面多见方解石充填物，一般以平行组系产出。裂缝以北东向和南北向组系有效性最高，砂岩中裂缝有效性高于泥岩裂缝的有效性。在裂缝特征认识的基础上，论文开展了有效裂缝的测井响应特征分析，认为各种探测深度的电阻率降低、声波时差增大、密度降低是天然有效裂缝的响应特征。因此采用判别分析、R/S分析、概率神经网络分析等方法，结合对裂缝孔隙度、渗透率参数的测井解释结果建立了适合构造平缓背景下红河油田长8油藏天然有效裂缝的常规测井综合识别标准。通过对红河油田长8油藏天然裂缝发育控制因素的研究认为，天然裂缝的发育与研究区断层、古构造应力演化、岩层厚度、岩性等因素有关。结合裂缝特征和力学性质，认为天然裂缝的成因为区域构造裂缝叠加断层共（派）生裂缝两种类型。通过岩石声发射实验、裂缝充填物稳定同位素分析，红河油田长8油藏天然裂缝主要形成时期为燕山期和喜山期，其中燕山期为关键时期，本次评价主要针对这两期天然裂缝开展了评价。本论文采用古构造恢复模拟了燕山期、喜山期古地应力场，对两期区域构造裂缝的分布进行了预测和评价。针对断层共（派）生天然裂缝建立了不同规模断层对裂缝发育的控制函数，预测和评价了断层共（派）生成因类型天然裂缝，并确定了不同规模断层对裂缝的控制距离。通过叠加这两种成因类型裂缝明确了研究区长8油藏天然裂缝的分布规律，从整体上看工区天然裂缝发育程度南部高于北部、断裂带内高于非断裂带区、砂岩发育区高于泥岩发育区。最后本论文从研究区油气地质条件入手分析了长8油藏的成藏背景及过程，充分考虑了构造、断裂、长7烃源岩与长8油藏砂体之间的配置关系，构建了长8油藏五种油气聚集成藏模式，即裂缝疏导成藏模式、断裂疏导成藏模式、源储接触成藏模式、砂体叠置侧向疏导成藏模式、组合疏导成藏模式。油气测试资料表明油气富集受控因素复杂，除了与断裂系统的分布关系密切，还受储层条件、成藏条件等各个因素的共同制约，因此各种成藏要素与断裂系统的匹配是红河油田长8油藏低孔低渗砂岩油藏油气富集以及获得高产的关键。更多还原

【Abstract】 Natural fractures occur commonly in the oil and gas reservoirs, especially in thearea with intense tectonic activities. For the sandstone reservoirs with low permeability,fracture systems are particularly important in hydrocarbon accumulation andsubsequent petroleum development. It has been proven by the exploration andexploitation of the oil pools in the member Chang8of southern Red River Oilfield inthe Ordos Basin studied in the paper for many years that fault and fracture systems arethe key to the hydrocarbon enrichment and large output in the development of thereservoirs. The characteristics, origination, stages, controlling factors of the fault andfracture systems and the relation with hydrocarbon enrichment in the Red River oilfieldare studied in depth, and then the distribution rule of the fault and fracture systems inthe reservoir of Member Chang8in the Red River Oilfield is figured out. Consideringhydrocarbon accumulation conditions and fracture controlling effects on theaccumulation, hydrocarbon accumulation models are constructed.Based on field investigation of cracks, description of core fractures and research offracture characteristics on imaging log, the basic characteristics of the cracks aresummarized that high-angle and vertical cracks mainly developed in the research areadominantly in the NE-SW group, secondly in the NW-SE group. The cracks cut throughthe different lithological layers vertically, extend a few meters to more than ten metershorizontally; shear ruptures and tensile ruptures occur together in the target layers in thestudy area among which shear ruptures developed in conjugated group, slickens andshear scratches in different directions or smooth fracture surfaces are visible, whereas tensile rupture surfaces are rough and uneven, bent-like, commonly with calcite fillingsand generally in parallel-group system. Fracture effectiveness is the best in NE-SW andSN groups is higher in the sandstone than that in the fractured shale. Based on theunderstanding of fracture characteristics, the paper analyzed logging responsecharacteristics of effective fractures, that is, low resistivity in various probing depth,increased acoustic value and slightly reduced density value. Therefore adoptingdiscriminant analysis, R/S analysis, probabilistic neural network analysis methodscombined with log interpretation parameters such as fracture porosity and permeability,the conventional logging standard for natural fracture identification in the reservoirs ofMember Chang8in Red River oil field is establish.It is believed through the research on control factors to the development of thenatural fractures in the reservoirs of Member Chang8in Red River oil field that thedevelopment of the natural fractures in the research area is related to faults, the ancienttectonic stress evolution, bed thickness, lithology and so on; it can be recognized on thebasis of the their characteristics and mechanical properties that regional tectonicfractures were superimposed by fault-associated (or fault-derived fractures). It isdetermined after rock acoustic emission experiment and stable isotope analysis offracture fillings that the natural fractures in the reservoirs of Member Chang8in RedRiver oil field developed mainly in the periods of Yanshanian and Himalayanmovements among which Yanshanian is critical period, the natural fractures developedin the two phases were evaluated in the paper.Paleostructure restoration in the paper simulated the ancient stress field in theperiods of Yanshanian and Himalayan movements, the distribution of tectonic fracturesin the periods is evaluated and predicted; in connection with fault-associated orfault-derived natural fractures, the control function to the development of differentscale faults is established, and the controlling distance of faults to the associatedfractures is determined. Finally the distribution pattern of the natural fractures in thereservoirs of Member Chang8was pointed out through superposition of the twogenetic types of cracks, and the development of the natural fractures is overall better inin the south part than in the north part, and in the fault zone than the non-fault zone, insandstone than in shale.Finally, the background and process of the hydrocarbon accumulation in thereservoirs of Member Chang8in Red River oil field are analyzed starting from thegeological conditions in the study area in the paper. After the matching of structures,faults, hydrocarbon source rocks and reservoirs is fully taken account of, five kinds hydrocarbon accumulation models for the reservoirs in the member Chang8are built,that is, cracks-divert accumulation model, fault-divert accumulation model,source-reservoir contacting accumulation model, the lateral-divert accumulation modelof stacked sand bodies and the combination-divert accumulation model; the controllingfactors to hydrocarbon-rich region obtained through well tests are complex, not onlythe fracture system but also the reservoir conditions, accumulation conditions and so on;the match of various accumulation factors and faults is the key to the oil and gasenrichment and to obtain high yield in the low porosity and low permeability reservoirsof Member Chang8in Red River oil field.更多还原