CO₂ injection into deep geological structures is very often accompanied by chemical interactions between the host rock and injected fluids and/or the in-situ created solute (i.e. carbonated brine). In fact, the in-situ reactions are considered one way through which the injected CO₂ may be trapped for perpetuity. Depending on the nature and mineralogy of the host rock formation, such reactions may eventually result in a degree of change in the petrophysical properties of the rock. Carbonate formations, due to the presence of highly reactive minerals in their composition, are expected to be more prone to such changes than their sandstone counterparts.

This manuscript presents the results of an experimental study conducted to evaluate possible changes in the petrophysical properties of five heterogeneous limestone samples (calcite concentration >91 wt%). The study includes five reservoir condition core-flood experiments (i.e. one per each rock sample) complemented by other laboratory measurements/analyses including porosity-permeability measurements, X-ray CT (X-ray Computed Tomography) and SEM (Scanning Electron Microscopy) imaging.

The results show a significant increase in the post-flood permeability of 80% of the samples caused by the dissolution and removal of carbonate minerals. The X-ray CT images reveal signs of significant mineral dissolution and establishment of flow paths through the initial larger pores in the samples leading, eventually, to the formation of wormhole features along the length of the samples. On the contrary, reduction in permeability is observed in one sample which was a relatively long (15.8 cm) composite sample consisting of two core segments placed one after the other in series. The other four samples were shorter with a nominal length of 6.4 cm. This reduction in permeability is observed predominantly in the outlet segment. This change is thought to have been primarily caused by possible migration of carbonate fines released by mineral dissolution in the inlet plug of the long composite core and to a lesser extent by the precipitation of minerals dissolved and transported from the inlet plug. This hypothesis finds further support in the pre- and post-flood dry weight measurements as well as a post-flood SEM image of the plug which reveals signs of fines migration and mineral precipitation. Slight reductions in the porosity and pore sizes are observed in most of the samples. This is likely to have been caused by the combined effect of fines migration, possible mineral precipitation and physical compaction mechanisms. Mechanical compaction is further evident from the reductions in the physical dimensions of the samples.

Overall, the results obtained show that the nature and degree of any change in the petrophysical properties of the rock samples vary to some degree from one sample to the next. This variation is found to depend on the significance and degree of dominance of the three mechanisms of mineral dissolution, mineral precipitation and mechanical compaction if they occur during the flooding process. The migration of carbonate fines also seems to be an important factor in shaping the post-flood sample properties. The presence of any initial core scale heterogeneity in the pre-flood samples is also believed to be a critical factor controlling the eventual outcome.

向深部地质结构中注入CO ₂常常伴随着基质岩石与注入流体和/或就地产生的溶质（即碳酸盐盐水）之间的化学相互作用。实际上，原位反应被认为是可以永久保留注入的CO _2的一种方式。根据宿主岩层的性质和矿物学，此类反应最终可能导致岩石的岩石物理性质发生一定程度的变化。碳酸盐岩地层由于其组成中存在高活性矿物，因此预计会比砂岩地层更容易发生这种变化。

该手稿介绍了一项实验研究的结果，以评估五个异质石灰石样品（方解石浓度> 91 wt％）的岩石物理特性可能发生的变化。该研究包括五个储层条件岩心驱替实验（即每个岩石样品一个），并辅以其他实验室测量/分析，包括孔隙度-渗透率测量，X射线CT（X射线计算机断层扫描）和SEM（扫描电子显微镜）成像。

结果表明，由于碳酸盐矿物的溶解和去除，导致80％的样品水淹后渗透率显着提高。X射线CT图像显示出明显的矿物溶解迹象，并通过样品中最初较大的孔建立了流动路径，最终导致沿样品长度方向形成虫洞特征。相反，在一个样品中观察到渗透率降低，该样品是相对较长（15.8cm）的复合样品，其由两个依次串联的芯段组成。其他四个样品较短，标称长度为6.4 cm。渗透率的降低主要在出口段中观察到。认为这种变化主要是由于矿物复合物中长大岩心入口塞中矿物溶解所释放出的碳酸盐细粉可能迁移所致，并且较小程度地是由于从入口塞中溶解并运输的矿物的沉淀所致。该假设为注水前后的干重测量以及塞子的注水后SEM图像提供了进一步的支持，该图像显示出细粒迁移和矿物沉淀的迹象。在大多数样品中观察到孔隙率和孔径的轻微降低。这可能是由于细粒迁移，可能的矿物沉淀和物理压实机制的综合作用引起的。通过减小样品的物理尺寸，机械压实进一步明显。

总体而言，所获得的结果表明，岩石样品的岩石物理特性的任何变化的性质和程度在一个样品到下一个样品中都在一定程度上有所不同。发现这种变化取决于矿物溶解，矿物沉淀和机械压实这三种机理的显着性和主导程度（如果它们在洪水过程中发生）。碳酸盐细粒的迁移似乎也是影响注水后样品性能的重要因素。洪水前样品中任何初始岩心尺度异质性的存在也​​被认为是控制最终结果的关键因素。