Comprehensive evaluation of effectiveness of dual-porosity sandstone reservoir: A case study from Chang 8~1 reservoir in Honghe oilfield in southwest of the Ordos Basin

Chang81reservoir in Honghe oilfield is a tight sandstone reservoir with dual porosity consisting of pores and fractures. Due to various interstitial material component,fine grain size,complex pore structure,poor physical condition and strong heterogeneity,effective reservoir characteristics are inconspicuous and production is generally low. In addition,production capacities among wells are significantly different owing to varying degrees of reservoir permeability improvement by fractures with different occurrences,openess and filling degree. Based on core analysis,experimental test and production data,five evaluation index,including logging facies,pore throat structure,physical property,permeability and fracture effectiveness,were selected to evaluate dual-porosity Chang81 reservoir and establish evaluation standards. Verified by 31 wells in Honghe oilfield,the evaluation results are consistent with production conditions.