石油侵位对碎屑储集岩成岩序列的影响及其与孔隙演化的关系——以塔西南坳陷石炭系石英砂岩为例  

Influence of Oil Emplacement on Diagenetic Sequence of the Clastic Reservoir Rock and It′s Relationship to the Porosity Evolution ——Taking the Carboniferous quartz sandstone in southeast Tarim depression as an example

作　　者：王琪[1,2] 史基安[1,2] 肖立新 薛莲花[1,2] 

机构地区：[1]中国科学院兰州地质研究所 [2]新疆石油管理局地调处地球物理研究所

出　　处：《沉积学报》1998年第3期97-101,共5页Acta Sedimentologica Sinica

基　　金：国家自然科学基金

摘　　要：塔里木盆地西南坳陷地区的石炭系石英砂岩为一套分布稳定的滨浅海相碎屑岩沉积，在不同地区均具有相似的初始孔隙度。但在成岩期间，由于受构造活动的影响，在塔西南坳陷内部形成了两个重要的次级构造单元，即巴楚隆起区和麦盖提斜坡区，从而导致石炭系石英砂岩经历了不同的埋藏成岩环境的改造，具体体现在其成岩演化序列上具明显的差异性。在巴楚隆起区石炭系砂岩经历了稳定的持续埋藏成岩环境的改造，其成岩演化序列比较完整，各种成岩矿物的溶解、沉淀均在水－岩两相反应系统中进行，成岩阶段可达晚成岩阶段Ｂ期，甚至Ｃ期，因此砂岩原生孔隙破坏严重，平均孔隙度小于５％。而在麦盖提斜坡区，石炭系石英砂岩由于埋藏成岩深度始终小于隆起区，因此其成岩阶段多分布在晚成岩Ａ期－Ｂ期，特别是石油侵位作用的影响，使成岩反应在水－油－岩三相介质中进行，从而抑制了多数自生粘土矿物的沉淀作用，导致成岩演化序列的不连续性，但同时又保存了许多有效的储集空间，使该区砂岩平均孔隙度保持在７％±，高于隆起区，据此认为麦盖提斜坡区是近期在石炭系砂岩储层中进行油气勘探的最有利区域。Carboniferous quartz sandstone distributed in the Southwest Depression of the Tarim basin is a set of widespread clastic deposit. During diagenesis, two important secondary structure units were formed in Southwest depression,i.e.,Bachu uplift and Maigaiti Slope, which caused the difference in diagenetic sequence of the Carboniferous quartz sandstone in two areas. Under the stable and continuous burial diagenetic environment, the sandstone reservior in Bachu uplift has a complete diagenetic sequence, and diagenetic stage could reach B period of late diagenesis and even C period. Thus, the sandstone porosity there was damaged seriously and the average porosity is less than 5%. Conversely, the diagenetic stage of the sandstone in Maigaiti Slope is mainly distributed between A period and B period of the late diagenesis due to the relatively lower burial depth compared with that in Bachu uplift.Especially, the influence caused by oil emplacement on the sandstone reservior changed the traditional diagenetic environment and made the diagenetic reaction take place in water oil rock three phases media which repressed the cementation of some authigenic clay minerals, resulting in the discontinuity of the diagenetic sequence, but, at the same time, many effective porosity was preserved causing the average porosity exceed 7% in Maigaiei Slope, which is clearly larger than that of the uplift area. For this reason, we believe that the Maigaiti Slope is the most favorable area for the oil exploration work in recent years.

关 键 词：石油侵位 成岩序列 孔隙演化 石英砂岩 油矿床 

分 类 号：P618.130.2[天文地球—矿床学]