| Popis: |
Logging evaluation of low resistivity oil&gas in sandstone reservoir is one of the most difficult problems in logging field. At present, There are many reasons for low resistivity of sandstone oil&gas, which basically emphasize the external reasons of low resistivity of oil&gas and enlarge the influence of single factor, However, how these causes affect the low resistivity of oil&gas and how much they affect? who didn’t in-depth study it, there is no suitable model for calculating the saturation of low resistivity oil&gas. This paper summarizes the favorable conditions for the formation of low resistivity oil&gas reservoirs, and makes experimental analysis, It is found for the first time that the main reason for the low resistivity of oil&gas is the high conductivity (equivalent additional conductivity) produced by a small amount of movable water or bound water in the effective pore or movable pore under the condition of network distribution, and the conductivity of bound water itself causes the reduction of reservoir resistivity, and the inner wall water of the hydrophilic rock pore throat and a small amount of water together form the network conductivity network and increase the equivalent additional conductivity. In this paper, the formation of equivalent additional conductivity is introduced in detail, and the influencing factors of equivalent additional conductivity are established. It solves the problem that the common saturation model based on volume model does not describe the high conductivity of a small amount of water. It can obviously improve the calculation results of hydrocarbon saturation of low resistivity oil&gas, and increase the calculated reserves of sandstone oil&gas reservoirs in the world. The new model is compatible with the old common model, and has good universality and applicability. The content of this article has been patented. |
