Reservoir Characteristic Study Of The Chang-8Oil Group Of Lu46Well Zhiluo Oil Field

The District of Dadonggou of ZhiLuo Oil Field, is located in the southeast Iraqi Shan Slope of the Ordos Basin. Lu46well area is located in northeast area of Dadonggou district. Yanchang reservoir group is the main producing formation, but with the constantly geological understanding focus shift to Chang6and Chang8reservoir group, the rich oil and gas is found, and some of the wells have been industrial oil flow. As the new exploration strata of Chang8, being lack of sedimentary characteristics, diagenesis and reservoir characteristics seriously impact on the latter part of the oil and gas exploration and development. Therefore, this paper aims to study the condition of Chang8reservoir group, with petroleum geology and sedimentology theory guided, using core data, thin section analysis, scanning electron microscopy, means of vitrinite reflectance test analysis, rock characteristics, diagenesis, reservoir structure and sediment analysis of the area are analysed as follows:Analysis showed that the deposition phase of the study area is mainly delta front-shallow lake sediments, and early underwater distributary channel developed best, which had experienced the process of the lake level uplift.Chang8reservoir rocks are consisted of arkose, lithic arkose. Quartz content is14-26%, with an average of20.88%. Feldspar content is42-76%, with average of57.83percent. Lithic content is3-9%, with an average of5.33%. The interstitial material clay are Miscellaneous base and carbonate cements, clay mineral cements, siliceous cement. Rock particles sorted psephicity the times circle-times prismatic. The main pore type are primary porosity and secondary porosity.Diagenesis analysis study shows that the main four diagenesis type in the studied area are mechanical compaction, cementation, metasomatism dissolved dissolution. With quantitative analysis of porosity evolution of the area, it is considered that the deterioration of reservoir properties in the region mainly due to the compaction and carbonate cementation, the average cement content is15.59%, is mainly clay minerals, carbonate minerals and siliceous. The diagenetic stage is in Diagenetic A Period.Combined with sedimentary petrology, petroleum geology theory, it is believed that reservoir in Lu46well area of Chang8belongs to the low porosity and low permeabilityreservoir, porosity average in the Chang81-1is11.26%, the penetration rate is0.64%;average porosity in Chang81-2is10.77%, the penetration rate is0.51%; the porosity averagein Chang82-1is11.94%, penetration rate is0.59%; porosity average in Chang82-2is11.26%and permeability is0.41%. The pore throats connectivity is poor, main pore combination typesare small pores-micro jets/fine roar and large pores-micro throat/fine roar type. Withstudy of deposition and diagenesis, it is considered that reservoir properties in Lu46wellsarea are mainly influenced by the originaldeposition material and late diagenesis.