Low Porosity And Permeability To Calcium Sandstone And Mudstone Thin Alternating Layers Of Resistivity Truth-seeking Approach

In west of Daqing Changyuan , Saertu and Gaotaizi oil layers contain clay shale and calcium, sand and shale in reservoir have thin mutually characteristic, and because the thickness of thin interbed layer is is smaller than 0.4m, has surpassed the resolution of each kind of well logging method, causing the explanation coincidence rate of interpretation continuously to be in a lower level , particular in water-flooded zones. Based on the characteristic and basic theory for logging interpretation, combined with the experience of correction method, this article develops formation thickness and the adjacent formation correction, the borehole correction, the lithological correction of the dual laterolog, prominenting electronic resistivity and the reservoir fluid intrinsic relations, achieved the goal of evaluating reservoir accurately.the electronic resistivity correction method firstly uses the theory correction chart to eliminate the mud divergence influence, and this article establishes the calcareous content, the shale content, the effective porosity, the cementation exponent, the water saturation computation model through petrophysics experimental data of sealing core, Finally establishes the core sample analysis water saturation and the reservoir electronic resistivity, the shale content, the calcareous content, the adjacent formation electronic resistivity, the resistivity of the formation water relations equation. Based the laterolog principle, it had determined the contribution of each geological parameter, the environment parameter to the log response, achieved formation thickness and the adjacent formation correction, the lithological correction. Taking the classics Archie's formula , the examinated the effect of correction. After the actual material examination, the average absolute error of computing the water saturation achieved 5.48pu. the average relative error achieved 8.75it have much significance in enhancing the explanation coincidence rate, especially in the explanation of water-flooded zones.