济阳坳陷大王庄地区石炭系太原组煤系地层碎屑岩优质储层特征及成因模式
- 收稿日期:
2023-11-02
- 网络出版日期:
2024-01-25
摘要: 济阳坳陷大王庄地区石炭系太原组煤系地层分布广泛，煤系地层中的优质储层控制因素对油气勘探有重要影响。以济阳坳陷大王庄地区太原组煤系地层碎屑岩储层为研究对象，利用铸体薄片观察、荧光薄片观察、阴极发光薄片观察、扫描电镜观察及能谱分析、流体包裹体岩相学和均一温度分析、激光剥蚀电感耦合等离子质谱仪分析、C-O同位素分析等技术，结合埋藏史和构造演化史研究，系统研究了济阳坳陷大王庄地区石炭系太原组煤系地层碎屑岩优质储层特征及成因模式。大王庄地区太原组煤系地层碎屑岩储层以岩屑质石英砂岩为主，优质储层储集空间以次生孔隙为主，溶蚀作用强烈，主要为大气淡水以及有机酸溶蚀形成的填隙物溶蚀孔和长石溶蚀孔，优质储层孔隙度大于8%，渗透率大于5×10-3 μm2。胶结物为两期石英次生加大边和两期碳酸盐胶结物，以碳酸盐胶结物为主。第一期石英次生加大边主要为来源于石英颗粒的压溶作用，第二期石英次生加大边主要为长石溶蚀供源。菱铁矿主要为同沉积—早成岩阶段由孔隙水沉淀形成，铁白云石主要与有机酸脱羧作用有关。济阳坳陷大王庄地区石炭系太原组煤系地层储层的成岩—成藏演化序列为，菱铁矿→第一期石英次生加大边→第一期黄色荧光油充注→高岭石→铁白云石→第二期蓝色荧光油充注→第二期石英次生加大边和高岭石→黄铁矿。原始沉积相控制了现今优质储层岩相的分布位置，优质储层主要受控于晚期抬升的大气淡水淋滤溶蚀作用以及埋藏有机酸溶蚀作用，同时受构造活动控制，优质储层与对接断层的距离较远，避免脱羧作用产生的CO2进一步沉淀形成铁白云石破坏储层物性。
The characteristics and genetic model of high-quality reservoir of clastic rocks in coal-bearing strata of Carboniferous Taiyuan Formation in Dawangzhuang area, Jiyang depression
- Received Date:
2023-11-02
- Available Online:
2024-01-25
Abstract: The coal-bearing strata of Carboniferous Taiyuan Formation are widely distributed in Dawangzhuang area, Jiyang depression, and the high-quality reservoir control factors in the coal strata have an important influence on oil and gas exploration. Combined with burial history, tectonic evolution history, multi-proxy analyses, including the cast thin sections, fluorescence, cathodoluminescence, scanning electron microscopy and energy spectrum, petrography of fluid inclusion and homogeneous temperature, and laser ablation inductively coupled plasma mass spectrometry, were conducted to systematically study the characteristics and genetic model of high-quality reservoir of clastic rocks in coal-bearing strata of Carboniferous Taiyuan Formation(C3t) in Dawangzhuang area, Jiyang depression. The clastic reservoir of Taiyuan Formation coal measure strata in Dawangzhuang area is mainly composed of lithic quartz sandstone. The high-quality reservoir space is dominated by secondary pores, and the dissolution is strong. It is mainly filled with interstitial materials dissolution pores and feldspar dissolution pores formed by atmospheric fresh water and organic acid dissolution. The porosity of high-quality reservoir is more than 8 %, and the permeability is more than 5 × 10-3 μm2. And two phases of quartz overgrowth and two phases of carbonate cements are developed, dominated by carbonate cements. The first phase of quartz overgrowth mainly derives from pressure dissolution of quartz particles, the second phase of quartz overgrowth is mainly sourced from the feldspar dissolution. Siderite is mainly formed by pore water precipitation in syndepositional-early diagenesis stage, and ankerite is mainly related to organic acid decarboxylation. The evolution process of the diagenesis-accumulation system of the clastic rock reservoir of coal measures strata of C3t in Dawangzhuang area of Jiyang depression is: siderite → first phase of quartz overgrowth → first-stage oil in yellow fluorescence emplacement → kaolinite → ankerite →second-stage oil emplacement in blue fluorescence → second phase of quartz overgrowth and kaolinite →pyrite. High-quality reservoirs are mainly controlled by sedimentary facies, tectonic action and diagenesis. The sedimentary facies controls the distribution of lithofacies of high-quality reservoirs. The high-quality reservoirs are mainly controlled by the late uplift of atmospheric fresh water leaching dissolution and buried organic acid dissolution. At the same time, they are controlled by tectonic activities. The distance between the high-quality reservoirs and the docking faults should be far away, so as to avoid the further precipitation of CO2 produced by decarboxylation to form ankerite to destroy the reservoir properties.
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