The relevance of the investigated problem is caused by a great deal of carbonate reservoirs among the world oil reserves and the low efficiency of existing widespread reservoir engineering as applied to these reservoirs (e.g., flooding). There is therefore a need for creation of new and improvement of existing oil production technologies, taking into account the specificity of these reservoirs and permitting to increase the oil recovery factor.
The paper presents a technology of cyclic water flooding for fractured reservoir to increase the oil recovery factor. This technology is based on the mechanism of multiple oil degassing and consists in the multiple reservoir pressure passing through the bubble point pressure, which permits to enhance the oil recovery factor by means of multiple dissolved gas work.
In previous studies of the efficacy of single or cyclic fractured reservoir stimulation purposely oil-in-place degassing the detailed oil displacement simulation has not been conducted and only qualitative assessments of oil recovery factor, which allow to conclude about the appropriateness of proposed enhanced recovery methods, has been conducted. In this work, the leading method in the study of the problem is the method of hydrodynamic simulation. Using oil-wet fractured reservoir models the existing oil recovery methods, based on the oil degassing mechanism, has been compared. The cyclic recovery drive, proposed in this work, was the most effective in terms of enhanced oil recovery.
The estimation of the cyclic oil displacement parameters, which allow to enhance the oil recovery factor, has been conducted. One of these parameters is the minimum bottom-hole pressure in the displacement cycles. The simulation results showed that an optimal value of the minimum bottom-hole pressure in the displacement cycles, at which oil recovery factor becomes maximum, exist and it depends on the critical water saturation of the reservoir.
An optimized version of the cyclic recovery drive with a variable minimum bottom-hole pressure in the displacement cycles, which allows to get an additional increase of oil recovery factor, is proposed by authors.Article submissions may be useful in designing of technological processes for fractured reservoir production using described technology of cyclic reservoir stimulation based on mechanism of the multiple oil degassing.
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