川中蓬莱地区震旦系灯影组四段储层成岩作用、孔隙演化及油气充注
- 收稿日期:
2023-11-16
- 网络出版日期:
2024-03-11
摘要: 【目的】川中蓬莱地区灯影组已获得重大勘探突破，但灯四段储层埋深大、时代老、成岩演化过程复杂，经历了多期次油气充注，储层孔隙演化与油气充注关系尚不清楚。【方法】基于区内钻井取心资料，通过薄片观察、阴极发光、原位微区元素分析、流体包裹体等手段对灯四段储层岩石学类型、储集空间特征、成岩作用类型、成岩演化序列、孔隙演化与油气充注关系进行了研究。【结果】蓬莱地区灯影组四段储层岩石类型主要为晶粒白云岩、颗粒白云岩和微生物白云岩三类；储集空间类型可划分为溶洞、孔隙和裂缝三种类型；主要的成岩作用类型有同生-准同生期溶蚀作用、表生期溶蚀作用、埋藏溶蚀作用、胶结充填作用、构造破裂作用、硅化作用和压实压溶作用。不同阶段的成岩作用共同控制了灯四段储层孔隙演化，其中对储层起建设性成岩作用为各时期溶蚀作用、破裂作用，对储层形成起破坏性成岩作用的为压实压溶作用、胶结充填作用。【结论】灯四段储层溶蚀孔洞中胶结物充填序列可划分为：第Ⅰ世代叶片状白云石→第Ⅱ世代粉晶白云石→第Ⅰ期沥青→第Ⅲ世代细晶白云石→第Ⅳ世代中晶白云石→第Ⅴ世代粗晶白云石→第Ⅵ世代巨晶-鞍形白云石→第Ⅱ期沥青→第Ⅶ世代石英、萤石等矿物。根据各期次胶结充填物所捕获的流体包裹体的类型、相态、均一温度等信息，重建了蓬莱地区灯四段油气充注过程：志留纪中晚期古油藏充注（第Ⅰ期古油藏）→加里东晚期古油藏破坏→中三叠世古油藏充注（第Ⅱ期古油藏）→晚侏罗世古油藏裂解生气→晚白垩世至今古油气藏-气藏的调整与定型，其中晚期油裂解气→气态烃的充注是灯影组四段气藏的主要形成期。
Reservoir diagenesis, pore evolution and oil and gas charging in the fourth member of Sinian Dengying Formation in Penglai area, central Sichuan
- Received Date:
2023-11-16
- Available Online:
2024-03-11
Abstract: [Objective]Dengying Formation in Penglai area of central Sichuan has achieved a major breakthrough in exploration, but the fourth member of Dengying Formation has experienced multiple stages of oil and gas charging due to its large burial depth, old age and complex diagenetic evolution, the relationship between reservoir pore evolution and oil and gas charging is still unclear. [Methods]Based on drilling coring data, the petrological types, reservoir space characteristics, diagenetic types, diagenetic evolution sequence, pore evolution and hydrocarbon charging of the fourth member of Dengying Formation were studied by means of thin section observation, cathodoluminescence, in situ microelement analysis and fluid inclusion. [Results and Discussions]The reservoir rock types of the fourth member of Dengying Formation in Penglai area are mainly crystalline dolomite, granular dolomite and microbial dolomite. The types of reservoir space can be divided into three types: cave, pore and fracture. The main diagenetic types are syngene-parsyngenetic dissolution, epigenetic dissolution, buried dissolution, cementation and filling, tectonic rupture, silicification and compaction. Diagenesis in different stages jointly controls the evolution of reservoir pores in the four members of Dengying Formation, among which the constructive diagenesis is dissolution and rupture in different periods, and the destructive diagenesis is compaction and pressure-dissolution and cementation and filling.[Conclusion] The filling sequence of cement in the solution holes of the fourth member of the reservoir can be divided into: the first generation blade-like dolomite → the second generation powdery dolomite → the first stage bitumen → the third generation fine crystalline dolomite → the fourth generation medium crystalline dolomite → the fifth generation coarse crystalline dolomite → the sixth generation giant crystalline saddle-shaped dolomite → the second stage bitumen → the seventh generation quartz, fluorite and other minerals. According to the information of fluid inclusions captured by cemented fill of each stage, such as type, phase state and homogenization temperature, the oil-gas charging process of Dthe fourth member of Dengying Formation in Penglai Area was reconstructed: Paleo-oil reservoir charging in the middle and late Silurian period (the first phase of fossil oil reservoir) → late Caledonian paleo-oil reservoir destruction → Middle Triassic paleo-oil reservoir charging (the second phase of fossil oil reservoir) → Late Jurassic paleo-gas cracking in paleo-oil reservoir → the adjustment and formation of paleo-gas reservoir from Late Cretaceous to present, in which the late oil cracking gas → gaseous hydrocarbon charging is the main forming period of the fourth member gas reservoir of Dengying Formation.
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