碱性成岩作用对低阻油层形成的影响——以鄂尔多斯盆地周家湾南部长6油层组为例

Influence of alkaline diagenesis on low resistance oil layer: A case study for Chang 6 Formatin in southern Zhoujiawan in Ordos Basin

综合运用铸体薄片、高压压汞、试油试采等资料,系统分析了周家湾南部长6油层组碱性成岩作用类型及其对低阻油层的影响。结果表明:研究区碱性成岩作用类型主要有绿泥石薄膜胶结、方解石胶结和石盐晶体;绿泥石薄膜的抗压实作用造成导电系统截面的增大,方解石胶结作用导致的束缚水含量上升,石盐晶体促进了方解石溶蚀孔的形成,这3种因素共同导致研究区油层电阻率降低。

Based on the data of the cast thin sections, the mercury injection, the well testing and the production test data, this paper systematically analyzes the alkaline diagenetic types and its influences on the low resistivity oil layer in Chang 6 Formation of southern Zhoujiawan. Results show that the three main types of alkaline diageneses in this area are the chlorite cementation, the calcite cementation and the rock salt crystal. Because of a strong eompaction resistance of the chlorite film, a large section of conduction system is formed, and the water retention is caused by the adsorption of the chlorite film, the calcite eementation results in a bound water content rising, the rock salt crystal contributes to the formation of the calcite dissolution pore, therefore, the reservoir resistivity is decreased in the studied area. The research result provides some guidance for the analysis of the low resistivity reservoir formation, and a basis fi^r the study of the low resistance reservoir distribution and development.