塔里木、四川和鄂尔多斯盆地海相碳酸盐岩规模储层发育地质背景初探

A Discussion on the geological background of marine carbonate reservoirs development in Tarim,Sichuan and Ordos Basin,China

前人对碳酸盐岩储层的研究重点关注储层的特征和成因上,很少关注规模储层发育的地质背景问题,而这又是深层油气勘探不可回避的问题。本文基于塔里木、四川和鄂尔多斯盆地碳酸盐岩储层实例分析,提出了不同类型储层规模发育的地质背景,认为相控型碳酸盐岩规模储层主要发育于蒸发台地、碳酸盐缓坡及台地边缘三类沉积背景,成岩型碳酸盐岩规模储层发育的控制因素复杂,具有较大的不确定性,受先存储层规模及热液规模的控制,受区域构造运动控制的成岩型储层一般具备规模发育的条件。本文还特别讨论了镶边台缘背景下台内礁滩储层的规模问题,指出障壁类型、障壁的连续性、台地类型、台内水深和地貌共同控制台内礁滩储层的规模。规模储层发育地质背认识对深层碳酸盐岩勘探领域评价具重要的指导意义,指出了塔里木、四川和鄂尔多斯盆地近期值得关注的礁滩、岩溶和白云岩三类深层碳酸盐岩储层勘探领域。

Previous studies on carbonate reservoirs were mostly focused on characteristics and origin,geologic background for largescale carbonate reservoir（ LSCR） development was often overlooked,which,however,is an inevitable issue in deep oil gas exploration. This contribution based on case studies,figures out the geologic background for development of various LSCRs in Tarim,Sichuan,and Ordos basins. Facies-controlled LSCRs were commonly developed in evaporated platforms,ramps,and platform margins.Diagenetic-controlled LSCRs exhibited large uncertainties because of complex controlling factors,and were generally constrained by the scale of pre-existed reservoirs and the amount of hydrothermal fluids. Moreover,the scale of reef shoal reservoirs in interior platforms with rimmed margins was discussed in this study. It was found that the scale of reef shoal reservoirs in interior platforms with rimmed margins was integratedly controlled by types continuities of barriers,types of platforms,and water depth geomorphology. These findings on geologic background for LSCR development could be applied in evaluations of deep burial carbonate reservoirs.Accordingly,favorable exploration areas of three categories（ i. e. reef shoal,karst,and dolomite） of deep carbonate reservoirs in Tarim,Sichuan,and Ordos basins are put forward.