Research On The Fluid Characteristics Identification Method Of Gao Taizi Oil Reservoir In Qijiabei Oilfield

The GTZ reservoir in QJB oilfield containing high calcium content, High content of calcium and reservoir relatively dense lead to dramatic increase of resistivity in some of the water layers. Water layers with high resistivity, oil-water layer and oil layer share similar characteristics on electric curves and electric distributions. The similarity makes it hard to distinguish these layers base on electric characteristics.Aiming at the technical problems above, the paper performed a series of research on the ’four properties’ of the layers based on core data, well logs and well tests data of QJB oilfield-GTZ oil reservoir. The paper concluded the macroscopic patterns of layer electric characteristics in different types, determined the sensitive logging curve to the reservoir with calcium and water and established a new interpretation method of fluid types in different layers. The paper also proposed a corresponding interpretation method (layer-stripped method) aiming at overcoming the difficulties of distinguishing electric characteristics in different fluid types. The core idea is to extract specific fluid type from others according to its typical electric characteristic. The first step is separating the dry layer from the production layer according to custom dry layer electric characters. The second step is extracting the water layer (especially the calcareous water layer) from the oil-water layers according to its high resistivity. On the one hand, the induction logging curve is selected because of its sensitivity to the water-bearing reservoir, on the other hand, the AC acoustic curve is used to perform the calcium correction on induction resistivity. The final step is to extract the oil layer from the oil-water layers by establishing the interpretation templates. This method decreased the interferences from dry layer and water layer (especially the calcareous water layer) to interpretations in oil-water layer and oil layer, thus increased interpretation accuracy. The accuracy of the interpretation chart established by the method is up to more than 95%. The coincidence rate of interpretation reached 100% in the back-to-back verifications with 3 actual wells. Perforation potential analysis of 22 wells later on proved the coincidence rate of interpretation is up to 86.2%.The effective thickness and physical properties in the block has been determined by formation testing method and oil production-like method. Deep lateral resistivity and AC acoustic curve are optimized to establish standard alternative template of effective thickness and electric properties. Mid value of micro-normal resistivity and return level of resistivity are optimized to establish low resistance layer deduction template, and the lower limit standard of effective thickness and electric properties in the block have been determined. Deep lateral resistivity and AC acoustic curve are optimized to establish standard alternative template of effective thickness and electric properties. Mid value of micro-normal resistivity and return level of resistivity are optimized to establish low resistance layer deduction template, and the lower limit standard of effective thickness and electric properties in the block have been determined. The method guaranteed the calculation accuracy of reservoir parameters based on existing core data, optimized well logs and the interpretation models of porosity and permeability.