【作者】 张兵；

【导师】 郑荣才；

【作者基本信息】 成都理工大学 ， 沉积学， 2010， 博士

【摘要】 生物礁滩是一种特殊的碳酸盐岩沉积物,具有独特的油气储集空间,是一种优良的碳酸盐岩储层。礁滩相储层在世界分布广泛,在我国分布也很普遍,如发育于川东地区上二叠统长兴组的一系列生物礁型气藏,但礁相油气藏储层预测一直是油气勘探难点,目前发现的礁型气藏多为随机钻遇,而预测成功的礁型气藏很少,因此,对长兴组礁滩相储层成因和分布规律开展研究,对提高预测成功率具有极其重要的理论和实践意义。本论文在总结国内外相关研究最新研究成果的基础上,以沉积学、石油地质学、地球物理学和碳酸盐岩储层地质学理论为指导,结合研究区地质背景,采用岩矿鉴定技术、碳氧稳定同位素、锶稳定同位素、铁锰锶微量元素和流体包裹体等先进的分析测试手段,对长兴组礁滩相储层成因、成岩系统及预测评价进行系统研究,取得以下几点进展:1.通过钻井、野外剖面、镜下薄片以及测井地震等资料的综合研究,对川东―渝北地区长兴组进行了沉积相特征系统研究,确定研究区长兴组发育有包括前缘斜坡、台地边缘生物礁、台地边缘浅滩、开阔台地和局限台地在内的五个沉积相带,并建立了相应的沉积模式,认为台地边缘生物礁和浅滩相带是最有利储层发育的相带。2.在岩心描述和岩矿分析基础上,在长兴组礁滩相沉积组合中识别出微晶白云岩、微-粉晶生物礁白云岩、生屑微-粉晶白云岩、生屑粉-细晶白云岩、细晶白云岩、中-粗晶白云岩等白云岩类型。按结构-成因特征将储层白云岩划分为准同生交代和埋藏白云岩化两种主要成因类型,按埋藏序列划分出准同生期白云岩化、早成岩期埋藏白云岩化、中成岩期埋藏白云岩化、晚成岩期埋藏白云岩化和构造隆升期碎裂化白云岩五个白云岩化期次,不同期次和成因的白云岩具有随着成岩强度加强,白云石有序度增高和MgCO3/CaCO3比值逼近1的演化趋势。3.通过对长兴组白云岩的结构-成因分类、成岩作用方式、成岩演化序列和碳氧锶稳定同位素、铁锰锶微量元素和流体包裹体地球化学特征的综合研究,从盆地大尺度的成岩作用组合特征出发,按“水文体制”将研究区长兴组白云岩划分为4个成岩系统,即准同生阶段孔隙卤水成岩系统、早成岩阶段地层封存卤水成岩系统、中-晚成岩阶段混合热液成岩系统、构造隆升阶段构造热液成岩系统。4.深入系统地研究了川东—渝北地区长兴组的储层特征,确定最有效的储集空间为晶间孔和晶间溶孔,其次为超大溶孔和粒内溶孔,部分为裂缝,结合研究区储层物性和孔隙结构参数等指标,对长兴组礁滩相储层进行了分类及评价,深入探讨了储层发育控制因素和分布规律,创造性地提出如下几点新认识:①区域上礁滩相带控制了储层区域分布和发展规模;②地层封存卤水成岩系统的埋藏白云石化是储层发育的基础;③混合热液成岩系统的埋藏白云石化扩大了储层分布范围和提高了储层质量;④而构造热液成岩系统的破裂作用和溶蚀作用是提高储层质量的关键。5.综合利用地质和钻井资料,探讨了川东—渝北地区长兴组储层类型,划分出针孔型、微裂缝-针孔型、孔洞缝型和裂缝性储层类型,确定研究区主要为前两种储层类型,在此基础上建立了不同储层类型的测井响应模式。6.在总结成藏基本地质条件的基础上,选择沉积微相类型、颗粒累计厚度、分布面积、储层有效厚度、物性、油气显示和油气运移路径等因素为综合定量评价指标,对川东—渝北地区长兴组各构造带礁滩相有利储层发育区进行了定量评价,指出了研究区内有利的勘探区域,为研究区内进一步的深化研究和勘探开发提供了地质依据。更多还原

【Abstract】 Reef-beach is a special type of carbonate sediments, which has peculiar hydrocarbon pore volume and is an excellent carbonate reservoir. Reef-beach reservoirs are widely distributed all over the world, and they are also common in our country. For example, a series of reef gas reservoirs have been founded in Changxing Formation of Upper Permian, eastern Sichuan Basin. However, the prediction of reef-beach reservoirs has always been the difficulty of hydrocarbon exploration. The most reef gas reservoirs so far have been founded by random drilling, while the successful prediction has been few. Therefore, the research on the origin and distribution rule of reef-beach reservoirs in Changxing Formation is of theoretical and practical significance to improving the prediction successs rate.The article was based on the latest achievements home and abroad and guided theoretically by sedimentology, petroleum geology, geophysics and cabonate reservoir geology. Combined with the geologic background of the area, and using rock-mineral identification, stable carbon, oxygen and strontium isotope, trace element of Fe, Mn and Sr, and fluid inclusion, a systematic research was made on the origin, diagenetic system, prediction and evaluateon of reef-beach facies reserveoirs. The conclusions are as follows:1.The characteristics of sedimentary facies of Changxing Formation in eastern Sichuan-northern Chongqing were studied sysmatically by drilling, field profile, thin section, logging and seismic data. Five depositional facies were developed in Changxing Formation, including foreslope, platform-margin reef, platform-margin shoal, open platform and restricted platform. The depositional model was established. The platform-margin reef and shoal facies are the most favorable reservoirs.2.Based on core description and rock-mineral analysis, the dolomite types were identified, including dolomicrite, micro-powder crystal reef dolomite, micro-powder crystal bioclastic dolomite, powder- fine crystal bioclastic dolomite, fine crystal dolomite, middle-macro crystal dolomite. According to the texture-genetic characteristics, they could be divided mainly into penecontemporaneous replacive dolomitization and buried dolomitization, which can be classified further as syngenesis dolomitization, early-diagenesis buried dolomitization, middle-diagenesis buried dolomitization, late-diagenesis buried dolomitization and structure crack dolomitization. With the increasing diagenetic degree, the degree of order of dolomites from different phases and genesis become higher and the ratio of MgCO3/CaCO3 is closer to 1.3.Through the comprehensive study of the texture-genetic classification, diagenetic manners and evolution stages, trace element characteristics of Fe、Mn、Sr,and isotopic geochemistry characteristics of carbon,oxygen,strontium and fluid inclusion of dolomites in Changxing Formation,four diagenetic systems of different stages and environments were divided in the dolostone of Changxing Formation according to“Hydrological system”, which were pore brine during penecontemporaneous stage, canning brine during early diagenetic stage, mixed hot brine during middle-late diagenetic stage and structure hot brine during tectonic uplift stage.4.The characteristics of reservoirs in Changxing Formation were studied intensively and sysmatically, it could be determined that the most effective pore space are intergranular pores and intergranular dissolution pores, the minor are outsized solution pores and intragranular dissolution pores, and the partial pore space are cracks. Combined with reservoir properties, pore structure parameters and other indicators, the reef-beach reservoirs in Changxing Formation were classified and evaluated, and the controlling factors for the reservoir development and distributions were discussed intensively. Such new acquaintances can be concluded as follows:①the reef-beach facies controlled regional distributions and development scales of the reservoirs;②burial dolomitization in sealed formation brine diagenetic systems was the foundation of reservoir development;③burial dolomitization of mixed hydrothermal diagenetic system expanded the reservoir distributions and improved the reservoir quality; and④the fracture and dissolution of structurally controlled hydrothermal diagenetic system were the key to improving the quality of the reservoirs.5.Synthesizing geology and drilling data, the reservoir types of Changxing Formation in eastern Sichuan-northern Chongqing were discussed, including Pinhole type, micro-crack- Pinhole type,pore-cave-crack type and crack type. The study area is dominated by the first two types, and then the logging response models for different reservoir types were established.6.On the basis of the concluded basic geological conditions for hydrocarbon accumulation, such factors were chosen as comprehensive quantitative evaluation indexes, including the sedimentary facies types, accumulative grain thickness, distribution area, effective reservoir thickness, property, hydrocarbon shows and hydrocarbon migration path. The favorable reef-beach reservoir development area of all structural belts were quantificationally evaluated in Changxing Formation, Eastern Sichuan– Northern Chongqing, and the favorable exploration areas within the study region were shown. They could provide a geological foundation for further study and exploration and development.更多还原