A new reservoir quality ternary plot (RQTP) of effective porosity, shale volume, and matrix is presented in this study. We show it to be a useful tool for first-order estimation of the petrophysical zones and reservoir classes of each unit within a reservoir. Subsequently, we combine the RQTP results with permeability and fracturing intensity data in carbonate rocks to provide a better overall characterisation of reservoir quality. The approach has been applied to the Butmah Formation, a thick variable carbonate succession of Liassic (Lower Jurassic) rocks in north-western Iraq. The RQTP approach divides carbonate reservoirs into classes according to: (i) a measure of porosity, (ii) the fraction of shale, and (iii) the fraction of non-shale matrix. The outcome of applying this model to the Butmah Formation indicates that the best reservoir quality is identified in Unit 4, which consists of fine to medium dolomite rocks. These rocks are not associated with anhydrite cement or dissolved later due to late dissolution, presenting as clean carbonate with complex pore network heterogeneity. These types of rocks were classified as Rc2 and Rc3 using the RQTP Model. By contrast, the worst reservoir qualities (Rc7) were identified in Unit 1 which is composed of cemented limestone that shows low pore network heterogeneity (predominantly uniform pore sizes), low porosity, and poor permeability.

本研究提出了一种新的有效孔隙度，页岩体积和基质的油藏质量三元图（RQTP）。我们表明它是对储层中每个单元的岩石物性区和储层类别进行一阶估算的有用工具。随后，我们将RQTP结果与碳酸盐岩中的渗透率和压裂强度数据相结合，以提供更好的储层总体特征。该方法已应用于Butmah组，这是伊拉克西北部Liassic（下侏罗纪）岩石的厚变碳酸盐岩层序。RQTP方法根据以下条件将碳酸盐岩储层划分为以下几类：（i）孔隙度的度量；（ii）页岩的比例；以及（iii）非页岩基质的比例。将这个模型应用到Butmah地层的结果表明，在第4单元中确定了最佳储层质量，该单元由细到中白云岩组成。这些岩石与硬石膏胶结物无关或由于后期溶解较晚而溶解，呈现为具有复杂孔隙网络非均质性的纯净碳酸盐。使用RQTP模型将这些类型的岩石分类为Rc2和Rc3。相比之下，在单元1中发现了最差的储层质量（Rc7），该单元由胶结石灰石组成，其显示出低孔隙网络非均质性（主要是均匀的孔径），低孔隙度和低渗透率。表现为具有复杂孔隙网络非均质性的清洁碳酸盐。使用RQTP模型将这些类型的岩石分类为Rc2和Rc3。相比之下，在单元1中发现了最差的储层质量（Rc7），该单元由胶结石灰石组成，其显示出低孔隙网络非均质性（主要是均匀的孔径），低孔隙度和低渗透率。表现为具有复杂孔隙网络非均质性的清洁碳酸盐。使用RQTP模型将这些类型的岩石分类为Rc2和Rc3。相比之下，在单元1中发现了最差的储层质量（Rc7），该单元由胶结石灰石组成，其显示出低孔隙网络非均质性（主要是均匀的孔径），低孔隙度和低渗透率。