The problem of estimation of low-resistivity reservoirs volumetric data is considered. Low-resistivity reservoirs are oil and gas saturated ones, which true resistivity is below its critical value at the oil-water interface. During tests it is possible to obtain substantial oil or oil with water inflow from low-resistivity reservoirs, which by the results of well logging materials interpretation are defined as water-saturated.
Bigradient (divergent) method of the spontaneous polarization logging is developed in KogalymNIPIneft Branch of LUKOIL-Engineering LLC in Tyumen. The method differs from the existing method of measuring the spontaneous potential by higher sensitivity to the resistance of part of layer, not changed by penetration of drilling fluid, and by higher resolving capacity along the axis of the well (interlayer stratification). Hardware-methodical complex allows to measure spontaneous potential with new scheme, the first and the second differences of the spontaneous potential - with divergent logging method of L.M. Alpin.
The original method of an oil and gas saturation index estimating of structurally complicated, including low-resistivity, reservoirs is developed. Also the variant of oil and gas saturation index estimating according to the standard spontaneous polarization logging in the complex with the electric methods of borehole survey according to proposed method is provided for. The example of interpretation of low-resistivity oil-saturated reservoirs of Jurassic deposits of Maloklyuchevoye field of LUKOIL-West Siberia LLC is given.
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