Oil Reservoir Description Of Chang 6 Reservoir In Madigou Area Of Ordos Basin

The Chang 6₁oil layer subgroup of the Upper Triassic Yanchang Formation in the Madigou area is a typical ultra-low permeability oil reservoir,its oil and gas resources have great potential,is one of the main oil-bearing zones in the area.However,the heterogeneity of the reservoir in this reservoir is strong-medium,leading recovery factor is relatively low,stable production is difficult to maintain.Therefore,strengthen the fine description of oil reservoirs,study the reservoir characteristics and oil-bearing law of each small layer,it can provide an important theoretical basis for improving oil recovery and ensuring stable oil production.Based on the multidisciplinary theories and methods of sedimentology,petroleum geology,stratigraphy,geophysics,stochastic modeling and geostatistics,this paper mainly uses drilling core data,logging and logging data to analyze the sedimentary microfacies in the study area,and carries on the fine description and three-dimensional modeling of the reservoir geological characteristics.finally,combined with the production performance data,the waterflooding effect of the oil field is comprehensively evaluated.The results show that the Chang 6₁reservoir in the study area is a delta sedimentary system,delta plain subfacies are developed,sedimentary microfacies are dominated by distributary channels and interchannels,the composition maturity of channel sandstone is low,it is feldspar sandstone,the reservoir is a low porosity,ultra-low permeability reservoir.The reservoir type is a typical structure-lithological reservoir,the volumetric method calculates the geological reserves as 125.29×10⁴t.Using petrel software for geological modeling,the established structural model,lithofacies model and attribute model are in good agreement with the geological research.The result of water injection effect analysis of each well group shows that the water injection has an effective rate of 62.5%,an average oil recovery rate of 0.11%,a recovery degree of 1.36%,a calibrated oil recovery factor of 13.95%,a reasonable oil recovery rate of 0.59%and a liquid recovery rate of 6.28%.The research results have certain guiding significance for the exploration and development of the research area.at the same time,it provides important reference for the development of water injection in the same type of reservoir.