Naturally fractured carbonate reservoirs are often described as very heterogeneous systems due to the carbonate depositional environment and to the subsequent diagenesis processes such as mineral precipitation in fractures. Fluid flow behaviour in fractures is highly influenced by the fracture aperture size and its morphology. Mineral precipitation can alter the fracture effectiveness to the fluid flow and cause a partial or entire blockage of fractures. Therefore, accurate characterisation of the fracture morphology can help to enhance the prediction of the fluid flow behaviour in naturally fractured carbonate reservoirs. Mineral precipitation on fracture walls can reduce the fracture aperture significantly. As a result, the fracture permeability affected notably, which reduces the flow potential through fractures as well as changes the flow pattern. The objective of this work is to predict the flow behaviour in fractures under various levels of mineral precipitation to mimic reality. We have approached this objective by using outcrop-based models supported by a set of rock and fluid properties of a nearby fractured formation. Then, the model tested for the gas flow using the derivative plot technique of the synthetic well testing data. The simulation results have shown that mineral cementation can cause a partial blockage in fractures, hence a reduction in their flow capacity, as fractures become a less conductive medium. Nevertheless, the matrix medium can enhance the fluid flow in fractures by providing a bypass path to the fluid to overcome the sealed fractures. In this work, a formula has concluded to estimate the reduction in fracture permeability based on the fraction of the precipitated cement. In the studied formation, the core description has shown that 34% of fractures were blocked, which can lead to a reduction in the permeability by 29–64% and by 37–83% with and without matrix contribution, respectively. Thus, including the fracture morphology in the simulation model enables us to predict the performance of fractured carbonate reservoirs accurately.

中文翻译：

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成岩沉淀对天然裂缝性碳酸盐岩储层裂缝渗透率的影响

由于碳酸盐沉积环境和随后的成岩过程（如裂缝中的矿物沉淀），天然裂缝性碳酸盐岩储层通常被描述为非常非均质的系统。裂缝中的流体流动行为受裂缝孔径大小及其形态的影响很大。矿物沉淀可以改变流体流动的裂缝有效性并导致裂缝的部分或全部堵塞。因此，准确表征裂缝形态有助于增强天然裂缝性碳酸盐岩储层中流体流动行为的预测。裂缝壁上的矿物沉淀可以显着减小裂缝孔径。因此，裂缝渗透率受到显着影响，这降低了通过裂缝的流动势并改变了流动模式。这项工作的目的是预测在各种矿物沉淀水平下裂缝中的流动行为，以模拟现实。我们通过使用由附近裂缝地层的一组岩石和流体特性支持的基于露头的模型来实现这一目标。然后，该模型使用合成试井数据的导数绘图技术测试气流。模拟结果表明，矿物胶结会导致裂缝部分堵塞，从而降低其流动能力，因为裂缝成为导电性较差的介质。然而，基质介质可以通过为流体提供旁路路径以克服密封裂缝来增强流体在裂缝中的流动。在这项工作中，一个公式已经得出结论，以根据沉淀的水泥分数来估计裂缝渗透率的降低。在研究的地层中，岩心描述表明 34% 的裂缝被阻塞，这会导致渗透率分别降低 29-64% 和 37-83%，有和没有基质贡献。因此，在模拟模型中包含裂缝形态使我们能够准确预测裂缝性碳酸盐岩储层的性能。