砂岩储层中凝灰质溶蚀效应的物理模拟实验研究——以珠江口盆地惠州—陆丰地区古近系文昌组为例

Physical simulation experiment of tuffaceous dissolution effect in sandstone reservoirs: a case study of Paleogene Wenchang Formation in Huizhou and Lufeng area, Pearl River Mouth Basin

李晓艳 彭光荣 丁琳 远光辉 张琴 吴琼玲 靳子濠

LI Xiaoyan PENG Guangrong DING Lin YUAN Guanghui ZHANG Qin WU Qiongling JIN Zihao

1. 中海石油(中国)有限公司 深圳分公司, 广东 深圳 518054; 2. 中海石油(中国)有限公司 深海开发有限公司, 广东 深圳 518054; 3. 中国石油大学(华东), 山东 青岛 266071

1. Shenzhen Branch, CNOOC, Shenzhen, Guangdong 518054, China; 2. Deep Sea Development Co., Ltd., CNOOC, Shenzhen, Guangdong 518054, China; 3. China University of Petroleum (East China), Qingdao, Shandong 266071, China

为认识埋藏过程中酸性流体对碎屑岩储层中凝灰质的溶蚀改造效应及控制因素，选取珠江口盆地珠一坳陷惠州—陆丰地区古近系文昌组凝灰质砂岩储层，设计开展了岩心尺度的流体—岩石相互作用模拟实验。通过显微镜下观察、流体成分分析、物性表征等方法，对比分析了实验前后不同流体流速、不同凝灰质含量条件下砂岩储层的溶蚀作用和物性响应特征。结果表明，酸性流体环境中凝灰质溶蚀现象普遍，但不同实验条件下，凝灰质溶蚀强度及储层物性响应不同：成岩体系的开放性与封闭性决定凝灰质的溶蚀作用强弱。相同岩石和相同酸性流体条件下，高流速开放体系中凝灰质溶蚀量高于封闭体系，且低流速相对封闭体系中溶蚀产物趋于沉淀，溶蚀作用增孔效应有限。凝灰质含量显著影响溶蚀效应，富凝灰质砂岩中溶蚀作用有限，含凝灰质砂岩和贫凝灰质砂岩能够溶蚀增孔，且含凝灰质砂岩的溶蚀增孔效率更高。凝灰质含量相对中等—较低的储层中，中浅层埋藏阶段的开放成岩流体体系最有利于粒间凝灰质溶孔的发育。经历晚期酸性流体溶蚀改造后，较易形成次生溶蚀型优质储层，这一认识有助于不同地区的溶蚀型储层甜点预测。

Tuffaceous sandstone reservoirs of Paleogene Wenchang Formation in Huizhou and Lufeng area of Zhu I Depression, Pearl River Mouth Basin were selected, and core-scale fluid-rock interaction simulation experiments were designed and carried out to explore the dissolution and modification effect of acidic fluid on tuffaceous components in clastic reservoirs during burial process and its controlling factors. The dissolution characteristics and physical property response characteristics of sandstone reservoirs under different fluid flow rates and tuffaceous contents before and after the experiments were compared and analyzed through microscope observation, fluid composition analysis, physical property characterization and other methods. The results showed that tuffaceous dissolution was common in acidic fluid environment, but the intensity of tuffaceous dissolution and the response of reservoir physical properties were different under different experimental conditions. Among them, the openness and closure of diagenetic system determined the intensity of tuffaceous dissolution. Under the same rock and acidic fluid conditions, the amount of tuffaceous dissolution in the high flow rate open system was higher than that in the closed system, and the dissolution products in the closed system tended to precipitate, which was not conducive to the preservation of dissolution pores. In addition, the content of tuffaceous components significantly affected dissolution effect, the tuffaceous-rich sandstone would not be conducive to dissolution porosity, while the tuffaceous-containing sandstone and tuffaceous-poor sandstone could increase dissolution porosity, and tuffaceous-containing sandstone has higher dissolution efficiency. Overall, in the reservoirs with relatively moderate to low contents of tuffaceous components, the open diagenetic system in the shallow-middle burial stage is most conducive to the development of dissolution pores of tuffaceous components. After the late stage of acidic fluid dissolution and modification, it is easier to form secondary dissolution-type high-quality reservoirs. This study is of great significance for the prediction of dissolution-type reservoir sweet spots in different areas.

中国海洋石油集团有限公司“十四五”重大专项(KJGG2022-0403)和崂山实验室科技创新项目(LSKJ202203402)联合资助。

https://doi.org/10.11781/sysydz202401173