Evaluation of opening of fractures in the Logovskoye carbonate reservoir, Perm Krai, Russia

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The development of naturally fractured carbonate reservoirs is extremely challenging. Such reservoirs have a dual pore structure consisting of low-permeable matrix with large pore volume and high-permeable fractures constituting main paths for fluid flow. Productivity of wells drilled in such formations tends to decrease rapidly due to the drop in the reservoir pressure and closure of fractures. Therefore, it is crucial to monitor opening of fractures for the effective development of carbonate reservoirs. Three methods for monitoring of opening of fractures including tracer indicators method, Warren and Root method and Victorin’s empirical relation, are applied in the Logovskoye oil reservoir, a carbonate Tournaisian-Famennian formation in Upper Kama Region, Perm Krai, Russia. The three methods provide reliable estimation of the opening of fractures, which match the reported laboratory data obtained on thin sections of core samples. The limitations of each method are also discussed. The tracer indicator method is time-consuming, the Warren and Root method includes hydrodynamic studies and requires shutdown of wells influencing the oil production, and the application of Victorin’s relation requires estimation of initial opening and current compressibility of fractures, which can be done using analysis of cores or tracer indicators studies. The appropriate method for monitoring of opening of fractures should be chosen according to available resources, time, and economic targets of the development project.