东营凹陷漫湖砂体与滩坝砂体成岩演化差异及优质储层成因机制

Over-flooding lake sandbodies in salt lake environment and beach-bar sandbodies in brackish lake environment are the two typical sandbodies in the Dongying depression. The unclear understanding of the diagenetic evolution processes of the over-flooding lake sandbodies in salt lake environment and beach-bar sandbodies in brackish lake environment and their differences leads to the uncertain of the genetic mechanism of the high-quality reservoirs controlled by the diagenetic evolution. According to the combination of methods of geochemistry and methods of basin numerical simulation, the evolution process of every element of reservoir diagenetic environments of the over-flooding lake sandbodies and the beach-bar sandbodies based on the multiple laboratory analysis data. Take all of the elements of diagenetic environment as a whole to remodeling the diagenetic environments of the over-flooding lake sandbodies and the beach-bar sandbodies and to study the differences. Combined the study of diagenetic simulation experiments, the distribution of the diagenetic products is quantified characterized based on the recovering of the diagenetic environments. The differences of reservoir diagenetic transformation between the over-flooding lake sandbodies and the beach-bar sandbodies are cleared and the reservoir diagenetic transformation models are established on the basis of recovering of the diagenetic environments and the distribution of the diagenetic products. We clarify the controlling factors and the genetic mechanism of high-quality reservoirs. The differences of the genetic mechanism of high-quality reservoirs of the over-flooding lake sandbodies and the beach-bar sandbodies will be studied. All of these are academic value and exploration significance for the recognition of the differences of diagenetic transformation and genetic mechanism of high-quality reservoirs between salt lake reservoirs and brackish lake environment clastic reservoirs.

盐湖环境漫湖砂体和咸化湖环境滩坝砂体是东营凹陷两种典型的砂体类型。对盐湖环境漫湖砂体和咸化湖环境滩坝砂体成岩环境演化过程及差异性认识不清，导致了成岩演化约束下的优质储层成因机制不明确。利用多种分析化验资料，采用地球化学分析和盆地数值模拟分析相结合的方法，恢复漫湖砂体和滩坝砂体储层成岩环境各要素演化过程，将它们作为统一的整体进行系统分析，重塑漫湖砂体和滩坝砂体储层埋藏成岩环境，研究其差异性。在成岩环境演化恢复的基础上，结合成岩模拟实验研究，量化表征漫湖砂体和滩坝砂体储层成岩产物分布规律。在此基础上，明确漫湖砂体和滩坝砂体储层成岩改造差异，建立相应的储层成岩改造模式，阐明优质储层发育的控制因素，明确优质储层成因机制，对比漫湖砂体和滩坝砂体优质储层成因机制的差异性。对于认识盐湖环境和咸化湖环境碎屑岩储层埋藏成岩演化规律及优质储层成因机制差异性具有重要的学术价值和勘探指导意义。

盐湖环境漫湖砂体和咸化湖环境滩坝砂体是东营凹陷两种典型的砂体类型。对盐湖环境漫湖砂体和咸化湖环境滩坝砂体成岩环境演化过程及差异性认识不清，导致了成岩演化约束下的优质储层成因机制不明确。利用多种分析化验资料，总结了漫湖砂体与滩坝砂体成岩作用特征及差异，漫湖砂体碱性成岩作用较强，酸性成岩作用较弱；滩坝砂体以酸性成岩作用为主，碱性成岩作用主要发育在砂体边缘。漫湖砂体储层主要经历了多重酸碱环境交替-开放环境上升流成岩环境演化过程；西段滩坝砂体储层经历了多重酸碱交替-早期开放-中期开放-晚期封闭成岩环境演化过程；东段滩坝砂体储层经历了多重酸碱交替-早期封闭-中期开放-晚期封闭成岩环境演化过程。在重塑成岩环境的基础上，建立了漫湖砂体和滩坝砂体储层成岩演化序列，明确了成岩产物分布规律，建立了4种储层成岩改造模式。漫湖砂体储层主要发育多重酸碱环境交替-开放环境上升流作用储层成岩改造模式，优质储层一般分布在断块中下部厚层砂体中部；高青地区漫湖砂体储层发育碱性-酸性环境演化-开放性环境下降流作用储层成岩改造模式，优质储层主要分布在不整合面之下一定的深度范围内，且储层质量随距不整合面距离的增加而明显变差；西段滨浅湖环境薄砂体储层发育多重酸碱交替-早期开放-中期开放-晚期封闭环境储层成岩改造模式，优质储层一般分布在断块中下部厚层砂体中部；东段滨浅湖环境薄砂体储层发育多重酸碱交替-早期封闭-中期开放-晚期封闭环境储层成岩改造模式，优质储层主要发育在断块中部厚层砂体中部。多重碱性及酸性成岩环境交替演化控制了储层成岩作用及储集空间分布格局，成岩环境封闭性及其控制的地层流体流动方式控制了储层储集物性分异特征。