塔里木盆地塔中45井区碳酸盐岩储层的深部流体改造作用

Transforming Effect of Deep Fluids on Carbonate Reservoirs in the Well TZ45 Region

塔里木盆地塔中地区发育巨厚的下古生界海相碳酸盐岩,是该地区油气勘探的重要目标层系。塔中45井在上奥陶统灰岩储层内获得高产油气流。研究发现其含油气层段因萤石脉的改造而发育成为优质储层,这在已发现的塔中地区下古生界碳酸盐岩储层中为一独特储集体类型。综合多方面地质依据对萤石成因的分析结果表明,该储集层段是与该地区二叠纪岩浆作用有关的深部流体活动对碳酸盐岩储层改造的结果。深部流体通过溶蚀作用、交代作用和充填作用等对碳酸盐岩储层进行改造,形成深部流体改造型碳酸盐岩储集体。这一新的储集体类型的确立,对塔中地区下古生界碳酸盐岩层系油气勘探有着重要的现实意义。

Lower Paleozoic marine carbonate rock with a great thickness is universally distributed in the Tazhong region of the Tarim basin. Carbonate rock is always an important oil and gas exploration target in this region. Well TZ4S was successful in prospecting Upper Ordovician carbonate rock reservoirs and has discovered high-yield hydrocarbon flows. This study revealed that oil-bearing strata in this region are an excellent reservoir. This is a special new kind of reservoir formed by the transformation of infilling fluorite veins. It is different from the Lower Paleozoic carbonate reservoirs found in the Tazhong region. Analysis of the genesis of fluorite in consideration of various geological evidences indicates that the reservoir resulted from the transforming effect of Permian magmatism-related deep fluids on carbonate rock reservoirs. The latter were transformed by the former through dissolution, metasomatism and infilling, so that carbonate rock reservoirs and oil-gas pools related to deep fluid transformation were form. The classification of such a new type of reservoirs and oil-gas pools is of important and practical significance to oil and gas exploration in Lower Paleozoic carbonate strata in the Tazhong region, especially in vast areas influenced by Permian magmatism, and in the west segment of the No. 1 fault zone in this region.