基于溶蚀模拟实验的碳酸盐岩礁滩储层形成及发育规律探讨

由于实验条件、方法和样品类型局限性, 对于礁滩体系与大气水溶蚀作用的控制因素认识尚不够深, 通过 选取不同结构组分的石灰岩样品开展大气水溶蚀模拟实验, 结合地质背景认识, 总结了碳酸盐岩礁滩储层的发育规律和 控制因素。实验表明: 各组构溶蚀程度自大到小依次为核形石颗粒>泥晶颗粒(砂屑和藻砂屑) >鲕粒、棘屑、亮晶方 解石>白云石; 总体上全岩溶解速率与组构溶解序列一致, 并与孔隙度密切相关。根据实验结果得出以下认识: ①碳酸 盐岩岩石组构和初始孔隙度对岩石溶蚀效率控制明显, 以颗粒灰岩的可溶性最好; ②岩相是控制礁滩储层发育分布的重 要因素, 礁滩储层在颗粒岩相中较为发育; ③初始孔隙度是决定礁滩储层发育程度的关键, 同时也决定了后期溶蚀改造 的发生范围; ④塔中台内地区良里塔格组的勘探应注意后期叠加改造因素的分析; 而台缘带勘探开发中应注意岩相、层 序界面和同生断裂等因素造成的储层非均质性刻画。

Laws of Formation and Development of Carbonate Reef-shoal ReservoirsBased on Dissolution Modeling Experiment

Being limited by experiment conditions, methods and sample types, it is still not much clear about the controlling factors of reef - shoal systems and meteoric water dissolution. By means of dissolution modeling experiment of meteoric water through selecting the limestone samples with various structural components, in combination with the cognition of geologic setting, we summarized the development law and controlling factors of carbonate reef-shoal reservoirs. The experiment results show that the degree of dissolution of each petrofabric, from the greatest to the least, in turn, is oncolite particle >micrite particle (arene and algal arene) >oolith, spinal crumbs/ scraps, sparry calcite (calcsparite) > dolomite; As a whole, the rate of dissolution of the whole rock is consistent with the dissolution sequence of the petrofabric, and is closely related to the porosity. We obtained the following cognitions: (1) Carbonate rock fabric and initial porosity have an obvious control effect on the dissolution efficiency, in which the granular limestone has the finest solubility; (2) Lithofacies is an important factor controlling the development and distribution of reef shoal reservoirs, and the reef shoal reservoirs assumed granular lithofacies development; (3) The initial porosity is the key factor to determine the degree of development of reefshoal reservoirs, and also determine the scope of the late dissolution transformation; (4) Attentions should be paid to analyzing the later superimposed transformation factors while exploring the Lianglitag Formation in intra-tableland zone of Tazhong; whereas developing in the edge zones of the tableland, we should pay attention to characterization of reservoir heterogeneity caused by the combination of lithofacies, sequence boundaries, and contemporaneous faults.