四川盆地开江-梁平台棚东侧长兴组礁白云岩沉积-成岩-成藏系统

发布时间：2018-05-13 21:03

本文选题：白云岩 + 成岩流体　；参考：《岩石学报》2017年04期

【摘要】：长兴组礁白云岩是川东北地区最重要的天然气储层类型之一。通过对开江-梁平台棚东侧长兴组礁白云岩岩石组构、成岩演化序列、铁锰锶微量元素、碳氧锶稳定同位素、流体包裹体、油气性质及来源综合研究,认为古地貌格局控制了开江-梁平台棚东侧不同类型台缘生物礁的展布,古海平面的"升降"控制了生物礁形态及规模,台缘礁坪/礁盖滩微相及部分毗邻发育的骨架礁相带控制了优质储层发育位置和空间展布规律;可将长兴组白云岩划分为准同生白云岩和埋藏白云岩两种成因类型,优质的礁、滩相白云岩储层仅与多期次埋藏白云石化作用有关,推测成岩流体主要来源于封存地层中的早-中三叠世蒸发岩溶解产生的具低Mn含量、较低Fe含量、高Sr含量、较高δ~(13)C值、较高~(87)Sr/~(86)Sr比值特点的高盐度埋藏循环海源孔隙水,并有长兴期同生卤水和深部有机酸热液混入;按水文体制,将长兴组白云岩成岩系统划分为4类,分别为海源同生卤水、封存卤水、混源热卤水和深源混合热卤水成岩系统,认为混源热卤水成岩系统埋藏白云石化和溶蚀作用是提高储层质量的关键;论证了开江-梁平台棚东侧长兴组存在同一流体输导体系控制的埋藏白云石化作用与油气充注成藏的统一"成岩-成藏"系统,揭示了长兴组白云岩沉积-成岩-成藏耦合关系,为该地区下一步天然气勘探目标优选提供地质依据。
[Abstract]:Reef dolomite of Changxing formation is one of the most important natural gas reservoir types in northeast Sichuan. The rock fabric, diagenetic evolution sequence, trace elements of iron, manganese and strontium, stable isotopes of carbon, oxygen and strontium, fluid inclusions, oil and gas properties and sources of reef dolomite of Changxing formation, east of Kaijiang-Liangpingpeng, were studied. It is considered that the paleogeomorphic pattern controls the distribution of different types of reef on the east side of Kaijiang-Liang platform shelf, and the "rise and fall" of paleo-sea level control the shape and scale of the reef. The microfacies of platform margin reef flat / reef cap beach and some adjacent skeleton reef facies belt control the development position and spatial distribution of high-quality reservoir, and the dolomite of Changxing formation can be divided into two genetic types of quasi-syngenic dolomite and buried dolomite, and the reef with high quality. The beach facies dolomite reservoir is only related to the multi-stage buried dolomitization. It is assumed that the diagenetic fluid is mainly derived from the lower mn content, lower Fe content, higher Sr content and higher 未 ~ (13) C value resulting from the dissolution of the early and middle Triassic evaporite in the sealed strata. The diagenetic system of dolomitic rocks of Changxing formation is divided into 4 types according to hydrological system, which is characterized by high salinity buried circulating marine source pore water with syngenic brine in Changxing period and deep organic acid hydrothermal solution, and the diagenetic system of dolomite in Changxing formation is divided into 4 types, respectively, according to the hydrological system, the diagenetic system of the dolomite in Changxing formation is divided into four types of marine syngenic brine, respectively. Sealing and storing of brine, mixed hot brine and deep source mixed hot brine diagenetic system, it is considered that burial of dolomitization and dissolution is the key to improve reservoir quality in mixed-source hot brine diagenetic system. It is demonstrated that there is a unified "diagenesis" system of "diagenesis" and "diagenesis" in the Changxing formation on the east side of Kaijiang-Liangtai platform, which is controlled by the same fluid transportation system and formed by oil and gas injection. The coupling relationship between sedimentary diagenesis and reservoir formation of dolomite in Changxing formation is revealed which provides geological basis for the further selection of natural gas exploration targets in this area.
【作者单位】：油气藏地质及开发工程国家重点实验室(成都理工大学);成都理工大学沉积地质研究院;中国石油西南油气田分公司;中国石油川庆钻探工程有限公司地球物理勘探公司;成都理工大学地球物理学院;
【基金】：中国地调局项目(1212011220762) 国家自然科学基金项目(41572097) 国家留学基金四川省教育厅自然科学重点项目(13ZA0058) 成都理工大学中青年骨干教师培养基金联合资助
【分类号】：P618.13

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