A dozen of inversion methods are applied and tested to estimate the permeability of the area where gas-fingering event has taken place in an Iranian carbonate reservoir located southwest of Iran. In a previous work, the gas-fingering event was detected by inverting the 3D seismic data and in this study the permeability model in that area is estimated. Because the lateral area of the gas-fingering event is narrow, the whole system conducting the injected gas can be considered as one rock unit system and therefore the assumption of horizontal linear steady-state flow can be applied. Inversion methods are exploited to determine the permeability in the interval of interest. The interval of interest is located at the crest and involves four wells among which one is the gas-injection well. To investigate the feasibility of such an approach and select the best possible inversion method, first a controlled experiment for the system is designed and studied. The porosity values of the system are known from seismic data inversion and the permeability values are the desired parameters. The permeability values at well locations are known via well-test data and are used as constraints in the inversion procedure. The interval of interest is discretized and a simulator is used to simulate the fluid flow in the controlled system in order to apply and validate the inversion methods. All calculations are performed in the MATLAB environment. According to the results from the controlled experiment, the Maximum Entropy and Total Variation methods were found to be the best two inversion methods which were successful in retrieving the true permeability model. Similar comparative study using different inversion methods is performed for the real case for which the results retrieved by the Total Variation method is most reliable as it suggests the best recovery of the permeability value for the check-well. An estimation of the fracture permeabilities for the area under study also indicated that the inverted permeability values are most representing the fracture permeabilities rather than the matrix. The results of this study will be used to tune the field simulation model in terms of rock and fluid properties, consider the inverted permeability model as further constraints for the reservoir history-matching of the oil field, reconsider the factors involving the gas injection plan for the oil field, and obtain insights for further field development plans in other nearby oil fields.

应用了十二种反演方法并进行了测试，以估算位于伊朗西南部的一个伊朗碳酸盐岩储层中发生气指事件的区域的渗透率。在先前的工作中，通过反演3D地震数据检测了气指事件，并且在本研究中，对该区域的渗透率模型进行了估算。由于气指事件的横向区域较窄，因此传导注入气体的整个系统可以视为一个岩石单元系统，因此可以采用水平线性稳态流的假设。利用反演方法确定感兴趣区间的渗透率。感兴趣的层段位于波峰处，涉及四口井，其中一口是注气井。为了研究这种方法的可行性并选择最佳的反演方法，首先设计并研究了该系统的受控实验。从地震数据反演中可以知道系统的孔隙度值，而渗透率值是所需的参数。井位置的渗透率值可通过试井数据得知，并用作反演程序中的约束条件。离散感兴趣的间隔，并使用模拟器来模拟受控系统中的流体流动，以便应用和验证反演方法。所有计算都在MATLAB环境中执行。根据对照实验的结果，发现最大熵法和总变异法是成功检索真实渗透率模型的最好的两种反演方法。对于实际情况，使用不同的反演方法进行了类似的比较研究，通过“总变化”方法检索的结果最可靠，因为这表明对检查井的渗透率值的最佳恢复。对所研究区域的裂缝渗透率的估算还表明，反渗透率值最能代表裂缝渗透率，而不是基质。这项研究的结果将用于对岩石和流体特性方面的现场模拟模型进行调整，将反渗透率模型视为对油田储层历史拟合的进一步约束，