Geologicheskii Vestnik

Microporous rocks are characterized by high porosity, low permeability and high residual water saturation. The purpose of the work is to test an algorithm for microporous rocks intervals identification based on resistivity logging data. To identify microporous rocks intervals containing residual water saturation it is proposed to calculate electrical resistance using mineral model for porous reservoir. It is known that free water conductivity and bound water conductivity are different. So actual electrical resistance in microporous rocks intervals will be greater than synthetic resistance calculated using mineral model which doesn’t take into account micropores. On the base of this assumption microporous rocks intervals are identified by using a technique of microprobes logging synthetic curves calculation. So the algorithm includes the following steps: calculation of porosity synthetic curve; building a volume model; calculation of resistance synthetic curve. For quality accession of developed algorithm comparative analysis between forecast microporous rocks intervals and microporous rocks intervals detected by the core is carried out: false positive rate and false negative rate are calculated. Testing of developed method for microporous rocks identification has revealed a good agreement between forecast intervals and intervals detected by the core. So application of proposed algorithm allows microporous rocks intervals identifying by electrical logging which allows specifying a thickness of reservoir and, consequently, fundamentally changes the concept of fluid model.

microporous rocks, calculation of resistance synthetic curve, resistivity logging, comparison with core data, false positive rate, false negative rate

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