潮湿环境下典型碳酸盐岩缝洞系统充填模式探讨

Typical filling models of a fractured-vuggy system in carbonate rocks under a moist environment

  • 摘要: 碳酸盐岩储层非均质性强,加上多期岩溶作用的充填改造,增大了开发的难度。塔北露头区奥陶系古岩溶和桂林的南方现代岩溶是古今潮湿气候环境下岩溶发育的代表,具有相似的岩溶发育条件和特征,可开展对比研究。本着"由表及里,将今论古"的原则研究古潜山岩溶,结合油田特点和以往研究成果,建立了几种潮湿环境下典型碳酸盐岩缝洞系统充填模式。按照水动力条件及充填物物源分类,可分为外源型地下河充填模式、内源型充填模式;按照充填结构分类,可分为上下结构充填模式、圈层结构充填模式、嵌入式混合充填模式等。不同的充填模式具有不同的充填程度和充填物类型,相应的岩溶储层也具有不同的物性特征,一般而言,外源型地下河充填模式储集性能优于内源型充填模式,上下结构充填模式储集性能优于圈层结构充填模式。

     

    Abstract: Carbonate reservoirs have strong heterogeneity, and were filled during multiple periods of karstification, which makes hydrocarbon exploration difficult. The Ordovician palaeo karsts in the northern Tarim Basin and the modern karsts in Guilin are examples of karst development in a moist environment, which have similar conditions and characteristics of karst development.According to the principles of "from the surface to the center" and uniformitaranism, combined with oil characteristics and previous research results, we established several typical filling modes of the fractured-vuggy system in carbonate rocks under a moist environment. According to hydrodynamic conditions and filling materials, they can be divided into exogenous underground river filling and endogenous filling models.According to filling structure classification, they can be divided into upper and lower structure filling model, circle structure filling model, and embedded mixed filling model.These models have various filling degree and types of filling material, and the corresponding karst reservoirs also have different physical properties.Generally speaking,the reservoir performance of the exogenous underground river filling modelis better than that of the endogenous filling model, and the reservoir performance of the upper and lower structure filling model is better than that of the circle structure filling model.

     

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