松辽盆地长岭断陷致密砂岩成岩作用及其对储层发育的控制

Diagenesis of tight sandstones and its controls on reservoirs genesis, Changling Faulted Depression, Songliao Basin

李易隆 贾爱林 吴朝东

Li Yilong Jia Ailin Wu Chaodong

北京大学 石油与天然气研究中心, 北京 100871 2. 中国石油勘探开发研究院, 北京 100083 3. 北京大学 造山带与地壳演化教育部重点实验室, 北京 100871

Institute of Oil and Gas, Peking University, Beijing 100871, China 2. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China 3. Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, Peking University, Beijing 100871, China

利用镜下鉴定、有机质分析与流体包裹体等资料,确定长岭断陷登娄库组与泉一段致密砂岩储层成岩阶段为中成岩A2期和B期。明确了主要成岩作用序列为:(1)早期方解石胶结;(2)斜长石钠长石化、自生浊沸石形成;(3)石英Ⅰ级次生加大;(4)钾长石溶解,自生纤维状伊利石与叶片状绿泥石形成;(5)石英Ⅱ、Ⅲ级次生加大;(6)残余钾长石少量溶蚀。导致砂岩储层致密的主要原因为强烈的压实作用和早期碳酸盐胶结物充填。其中,机械压实作用使最大埋藏深度大于3 000 m的砂岩储层损失70%以上的原生孔隙,是储层致密的主因。长石溶蚀是优质储层的主要成因,其中溶蚀作用以钾长石溶蚀为主,钠长石次之。

Based on rock analyses under microscope, organic matter analyses, fluid inclusion data and so on, the diagenesis stages of the Denglouku Formation and the first member of the Quantou Formation in the Changling Faulted Depression have reached the stages A2 and B. The diagenesis sequences of tight sandstones have been determined as followed: (1) Early calcite cement; (2) Albitization of plagioclase and generation of authigenic laumontite; (3) Ⅰ-grade quartz overgrowth; (4) Dissolution of potassium feldspar and generation of authigenic fibrous illite and authigenic chlorite; (5) Ⅱ- and Ⅲ-grade quartz overgrowth; (6) Subtle dissolution of remained potassium feldspar. Strong compaction and early calcite cement resulted in the densification of sandstones. Due to compaction, over 70% of primary pores lost in the sandstone reservoirs buried over 3 000 m deep, which was the main cause for reservoir densification. Secondary pores as a result of feldspar (especially potassium feldspar) corrosion which was controlled by the activity of diagenesis fluid in open system, were the main cause of high-quality reservoirs.

国家重大科技专项(2011ZX05015)资助。

https://doi.org/10.11781/sysydz201406698