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埋藏成岩过程中碳酸盐的溶解与沉淀强烈控制着深埋藏地层中碳酸盐岩储层质量,与之有关的地质过程是人们多年来不懈研究的热点领域。热流体沿断裂向上运移所造成的碳酸盐溶解成为近年人们普遍认可的模式,但这不能圆满解释大量存在的不与断裂伴生的深埋藏碳酸盐的溶解机制。基于四川盆地东北部和塔里木盆地北部深埋藏碳酸盐溶解与沉淀机制的研究,认为埋藏过程中盆地的沉降与抬升是碳酸盐溶解与沉淀以及次生孔隙发育的另一重要机制,在改变流体对碳酸盐饱和状况方面具有和热流体沿断裂向上运移相同的重要性。研究表明:与川东北飞仙关组类似的埋藏历史更有利于深埋藏成岩过程中碳酸盐的溶解,主要特点是当前埋藏深度不是最大埋藏深度,在最大埋藏深度附近发生热化学硫酸盐还原作用,其后盆地持续抬升造成温度降低和碳酸盐溶解,与之有关的次生孔隙形成所造成的岩石力学性质的变化与上覆载荷减小可以得到平衡,次生孔隙得以保存,岩石储层质量改善;塔里木盆地北部的奥陶系埋藏历史不利于深埋藏成岩过程碳酸盐的溶解,主要特点是当前埋藏深度是最大埋藏深度,古喀斯特发生之后盆地持续沉降造成温度升高和碳酸盐沉淀,并与上覆载荷的增加同步发生,结果是孔隙的封堵、岩石的致密化和储层质量的变差。
The dissolution and deposition of carbonate during burial diagenesis strongly control the quality of carbonate reservoirs in deep-buried formations. Geological processes related to these are the hot topics that people have been relentlessly studying for many years. The dissolution of carbonate caused by the upward migration of thermal fluids along the fault has become a widely recognized pattern in recent years, but this can not satisfactorily explain the dissolution mechanism of a large number of deep-buried carbonates that are not associated with faults. Based on the studies of deep-buried carbonate dissolution and sedimentation in the northeastern Sichuan Basin and the northern Tarim Basin, it is believed that the sedimentation and uplift of the basin during the burial process is another important mechanism for carbonate dissolution and sedimentation and secondary pore development. Fluids have the same importance of carbonate saturation as migrating up of thermal fluids along a fault. The results show that the burial history similar to Feixianguan formation in northeastern Sichuan is more favorable for the dissolution of carbonate during deep-burial diagenesis. The main feature is that the current burial depth is not the maximum burial depth, and thermochemical sulfate reduction occurs near the maximum burial depth The subsequent upwelling of the basin resulted in the decrease of temperature and the dissolution of carbonate. The changes of rock mechanics properties and the overburden caused by the secondary pore formation associated with it can be balanced, and the secondary pores can be preserved. The quality of the layers is improved. The history of the Ordovician burial in the northern part of the Tarim Basin is not conducive to the dissolution of carbonate during deep-burial diagenesis. The main feature is that the current burial depth is the maximum burial depth. After the karst occurred, Salt precipitation, which occurs in parallel with the increase in overburden, results in plugging of pores, densification of rocks, and deterioration of reservoir quality.