Study On Resistivity Anisotropy And Evaluation Of Sand Shale Thin Bedded Reservoir

A considerable amount of oil and gas from thin sandstone layer had been developed frommany large oil and gas fields in the world, According to previous estimated, about30percent ofglobal reserves occurrence in thin sandstone layer and fractured lithology reservoirs, Theresistivity of the two strata showed macroscopic anisotropy, That is, on horizontal and verticalorientation the resistivity are different. However, the resistivity which conventional inductionlogging measured is formation transverse resistivity,when using it to calculate the formationhydrocarbon saturation will be underestimated, this will result in missed petroleum reservoir. Inorder to solve the problem of sandstone thin interbedded and mudstone evaluation andexplanation, developed vector induction logging instrument, and the instrument drived formationresistivity anisotropy fast development, Due to technical, cost, and many other reasons, theapplication of three-component induction logging in domestic major oil field is still very small,sandstone thin interbedded and mudstone evaluation and explanation mainly use conventionallogging suite and array resistivity array induction resistivity well logging methods.In Changqing oilfield, sandstone and mudstone thin interbed development, Conventionallogging is difficult to evaluate sandstone and mudstone thin interbed, And not havethree-component induction logging, In this paper, combined FMI and conventional logging, thearray lateral array induction resistivity log，developed a method to evaluation sandstone andmudstone thin interbed Anisotropic and Reservoir Characteristics.First, analyze electrical properties and logging response of sandstone and mudstone thininterbed, Then analyze the existing thin sandstone reservoirs resistivity anisotropy evaluationmodel, This paper based on the Mollison model,under the Situation of no multi-componentinduction logging instrument, Uing FMI high resolution, Established Resistivity anisotropymodel. Calculate the horizontal resistivity and vertical resistivity separately, Using FMI data,separately Combined with conventional lateral logging data,array lateral logging data and arrayinduction logging data, We can obtain the resistivity of thin sand reservoir through verticalresistivity and horizontal resistivity and put forward the evaluation methodology of anisotropy inthin interbed sand-mudstone layer, which is the base of evaluation of anisotropy in thin sandreservoir. Based on the anisotropy of reservoir and the real resistivity that is calculated in thinsand reservoir. Basing on the anisotropy of reservoir and the real resistivity that is calculated in thin sandreservoir,Using GR and SP calculate formation total shale content, using FMI calculatelaminated shale content, then using Thomas-Stieber cross plot calculate effective porosity of puresandstone without dispersed shale. In this way, we can get a real reservoir water saturationbasised on Archie’s equation, then to improve porosity, saturation evaluation accuracy, using coreporosity and permeability relationship of actual area to evaluation permeability.In this paper, using plot method(Including acoustic and resistivity crossplot plates, neutronand resistivity crossplot Plate), Neutron-density combined method, P wave elastic modulusdifferential ratio method, and Anisotropy coefficient method to identify fluid properties.The above method has a good application in north Sulige.