川中地区蓬莱气区龙王庙组储层特征及其与磨溪-高石梯地区对比
Characteristics of Longwangmiao reservoirs in Penglai gas area and comparison with those in Moxi-Gaoshiti area, central Sichuan Basin
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摘要: 川中蓬莱气区下寒武统龙王庙组钻遇良好碳酸盐岩储层,天然气显示好,成为继川中地区安岳大气田后龙王庙组重点勘探区之一,但储层发育规律不明制约了勘探部署。基于最新的钻井及分析测试等资料,系统分析了蓬莱气区龙王庙组储层特征及主控因素。研究认为,蓬莱气区龙王庙组具有陆源碎屑与碳酸盐混合沉积背景,储层主要分布在龙王庙组中上部;储集岩石类型主要为(残余)颗粒白云岩和结晶白云岩;储集空间类型主要为粒间溶孔、粒内溶孔、晶间溶孔及微裂缝;以低孔低渗储层为主,储层厚度主要介于10~42 m之间。储层发育受控于层序地层、岩性及成岩作用等,进积型准层序组和准层序中上部的(残余)颗粒白云岩和结晶白云岩是储层发育主要部位,大气淡水溶蚀、油气溶蚀作用及破裂作用是核心建设性成岩作用。对比安岳大气田主体区磨溪-高石梯地区,认为储层主控因素相近,主要受颗粒白云岩、溶蚀作用、破裂作用等控制,但蓬莱气区龙王庙组储层具有灰质含量高、陆源碎屑含量多、准同生期暴露弱等特点,寻找准同生期暴露的高能颗粒白云岩和细晶白云岩及表生岩溶改造的白云岩是蓬莱气区重点关注的储层目标。Abstract: The Longwangmiao Formation in the Penglai gas area has encountered good carbonate reservoirs and good gas shows. It has become one of the key exploration areas of the Longwangmiao Formation after the Anyue gas field in the central Sichuan area. However, the unclear reservoir development law restricts exploration deployment. Based on the latest drilling and testing data, the reservoir characteristics and main controlling factors of Longwangmiao Formation in Penglai gas area are systematically analyzed. The study shows that the Longwangmiao Formation in Penglai gas area has a mixed sedimentary background of terrigenous debris and carbonate, and the reservoirs are mainly distributed in the upper part of the Longwangmiao Formation. The reservoir rock types are mainly (residual) granular dolomite and crystalline dolomite. The reservoir space types are mainly intergranular dissolved pores, intragranular dissolved pores, intercrystalline dissolved pores and microfractures. The reservoir is mainly composed of low porosity and low permeability reservoirs, and the reservoir thickness is mainly between 10-42 m.Reservoir development is controlled by sequence stratigraphy, lithology and diagenesis. The (residual) granular dolomite and crystalline dolomite in the middle and upper parts of the progradational parasequence set and parasequence are the main parts of reservoir development. Atmospheric freshwater dissolution, oil and gas dissolution and fracture are the core constructive diagenesis. Compared with the Moxi-Gaoshiti area in the main area of Anyue gas field, it is considered that the main controlling factors of the reservoir are similar, which are mainly controlled by granular dolomite, dissolution and fracturing. However, the Longwangmiao Formation reservoir in Penglai gas area has the characteristics of high ash content, high terrigenous clastic content and weak penecontemporaneous exposure. Looking for high-energy granular dolomite and fine-grained dolomite exposed in the penecontemporaneous period and dolomite modified by supergene karst are the key reservoir targets in Penglai gas area.
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