断陷湖盆致密砂砾岩储层成岩作用及其对孔隙演化的影响

Diagenetic characteristics and their control on porosity of sandy conglomerate reservoirs in faulted basins

郝杰 周立发 袁义东 杨燕 刘艳妮 程兆兆 刘挺

HAO Jie ZHOU Lifa YUAN Yidong YANG Yan LIU Yanni CHENG Zhaozhao LIU Ting

1. 西北大学 地质学系, 西安 710069; 2. 陕西省能源化工研究院, 西安 710050; 3. 陇东学院 能源工程学院, 甘肃 庆阳 745000; 4. 中国石油 长庆油田分公司 勘探开发研究院, 西安 710018; 5. 长城钻探工程有限公司 压裂公司, 辽宁 盘锦 124107

1. Department of Geology, Northwest University, Xi'an, Shaanxi 710069, China; 2. Shaanxi Provincial Institute of Energy Resource & Chemical Engineering, Xi'an, Shaanxi 710050, China; 3. School of Energy Engineering, Longdong University, Qingyang, Gansu 745000, China; 4. Research Institute of Exploration and Development of Changqing Oilfield, PetroChina, Xi'an, Shaanxi 710018, China; 5. Fracturing Company of the Great Wall Drilling Engineering Co., Ltd., Panjin, Liaoning 124107, China

为了明确松辽盆地北部徐家围子地区沙河子组致密砂砾岩储层成岩作用对孔隙演化的影响，通过普通薄片鉴定、铸体薄片观察、扫描电镜和X-衍射测试方法，在砂砾岩储层岩石学与成岩作用分析的基础上，建立了砂砾岩成岩作用与孔隙演化的定量关系模式。结果表明，沙河子组砂砾岩储层的岩石成分复杂、成熟度低、物性差；砂砾岩储层的成岩作用类型丰富，压实作用、胶结作用和溶蚀作用较为常见，对孔隙度影响较大；破裂作用、交代作用和重结晶作用对储层孔隙度影响较小。通过成岩作用与储层孔隙度关系的定量研究，认为压实作用对孔隙度破坏最大，平均减孔24.7%，是砂砾岩储层致密的主要原因；溶蚀作用改善储集性能，平均增孔4.2%，延缓了砂砾岩储层的致密化过程；胶结作用充填残余粒间孔隙，平均减孔5.3%，是砂砾岩储层致密的关键。砂砾岩储层的现今孔隙度是早期压实、中期溶蚀和晚期胶结综合作用的结果。

The petrography and diagenesis of sandy conglomerate reservoirs from the Shahezi Formation of the Xujiaweizi area in the Songliao Basin were studied, and the controls of diagenesis on porosity evolution were analyzed based on thin section identification, cast thin section observation, SEM and X-ray diffraction. A quantitative model was established. The results showed that the sandy conglomerate reservoirs in the Shahezi Formation are characterized by complex components, low maturity and poor physical properties. Various diagenetic effects took place in the sandy conglomerate reservoirs, among which the compaction, cementation and dissolution effects are very common and obviously influence porosity, while fracturing, metasomatism and recrystallization effects have little control on porosity. The quantitative evaluation of the relationship between diagenesis and reservoir porosity showed that compaction greatly reduced porosity, by 24.7% in average, which was the main reason for reservoir densification. Dissolution increased porosity by 4.2% in average, which delayed the densification process. Cementation filled residual intergranular pores, reducing porosity by 5.3% in average, which was also a key factor for reservoir densification. The porosity of sandy conglomerate reservoirs is the comprehensive result of early compaction, medium erosion and late cementation.

国家科技重大专项（2017ZX05009-002）资助。

https://doi.org/10.11781/sysydz201805632