鄂尔多斯盆地西南部长8砂岩中方解石胶结物表面绿泥石膜的形成机制

发布时间：2018-07-01 18:25

本文选题：绿泥石膜 + 方解石胶结物　；参考：《西安石油大学学报(自然科学版)》2017年03期

【摘要】：在鄂尔多斯盆地西南部延长组长8砂岩的方解石胶结物表面发现了绿泥石膜,通过铸体薄片和带有能谱仪的扫描电镜对这种新发现的绿泥石膜进行分析测试,研究其形成机制和过程及对砂岩致密化的影响。研究认为,这种新发现的绿泥石膜是方解石胶结物发生溶解-沉淀反应的产物。中成岩A期,油气携带酸性流体进入砂岩,方解石胶结物开始溶解。由于此时砂岩的渗透率低,流体流动缓慢,导致酸性流体供给不足,同时溶出的钙质流体也不能及时运移出去,二者共同作用促使方解石胶结物周缘迅速转化为碱性微域,随之方解石沉淀,有钙质参与的绿泥石膜生长。溶解-沉淀反应过程中,方解石胶结物的粒缘溶孔不断扩大,形成的绿泥石晶体逐渐增大,晶形变好,晶间微孔增多。这种新发现的绿泥石膜为方解石胶结物形成于成岩早期提供了令人信服的证据,揭示鄂尔多斯盆地西南部长8砂岩的致密化过程发生在早成岩阶段,而成岩晚期则是一个扩容过程。
[Abstract]:A chlorite film was found on the surface of calcite cemented material of 8 sandstone formations in the southwestern part of Ordos Basin. The newly discovered chlorite film was analyzed and tested by casting thin plate and scanning electron microscope with energy spectrometer. The mechanism and process of formation and the influence on the densification of sandstone were studied. It is considered that the new chlorite film is the product of dissolution-precipitation reaction of calcite cement. In stage A of middle diagenesis, oil and gas carry acidic fluid into sandstone and calcite cement begins to dissolve. Due to the low permeability and slow fluid flow of sandstone at this time, the acid fluid supply is insufficient and the dissolved calcium fluid can not be transported out in time. As a result, calcite precipitates, with calcium involved in the growth of chlorite film. In the process of dissolution-precipitation reaction, the dissolution pore of calcite cemented is enlarged, and the formation of chlorite crystal gradually increases, the crystal shape becomes better, and the intergranular micropores increase. The newly discovered chlorite film provides convincing evidence for the formation of calcite cementation in the early diagenesis, and reveals that the densification process of 8 sandstone in southwestern Ordos Basin occurred in the early diagenetic stage. The late diagenesis is a process of expansion.
【作者单位】：中国石油大学(北京)石油工程学院;中国石油大学(北京)石油工程教育部重点实验室;中国石油长庆油田分公司勘探开发研究院;低渗透油气田勘探开发国家工程实验室;
【基金】：国家科技重大专项“特低渗油藏有效开发技术”(编号:2011ZX05013-006) 国家级矿产资源综合利用示范基地项目“长庆姬塬油田特低渗透油藏综合利用示范基地”(国土资厅发[2011]88号文件)
【分类号】：P578;P618.13

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