Chang6 Reservoir Evaluation Of Si Zengcha Block In Wuqi Oilfield

Wuqi oilfield has bifurcation area located in the Midwest yishan slope,ordos basin,yanchang group 6 reservoir group as one of the main oil bearing strata,geological research degree is weak,unknown reservoir characteristics,the development effect is poor.Paper on the basis of core observation,through the reservoir physical properties,the casting thin sections,granularity analysis,porosity,cathodoluminescence image as well as conventional analytical means such as mercury intrusion,chang6 reservoir in wuqi oilfield has bifurcation area characteristics of careful study,analysis of main controlling factors,relatively high quality reservoirs built in the study area reservoir evaluation standard,the comprehensive evaluation of reservoir and provide a basis for further exploration and development.The study of Chang 6 oil-bearing formation can be subdivided into 61,62,63,long 64 four sub oil group,the Chang 61 and Chang 62 reservoir group is the main oil-bearing area,mainly developed delta front subfacies,further subdivided into underwater distributary channel,interdistributary bay.The lithology of Chang 6 oil-bearing formation is mainly grayish grey,gray brown,color block like fine-grained feldspathic sandstone and lithic feldspar sandstone.The average content of interstitial substance is 12.4%,and the total content is higher.Chang 6 reservoir porosity is 10.5% on average,the average value of the permeability is 0.72 * 10-3 m2,Kong Te belongs to the low low permeability reservoir.The main diagenetic processes are compaction,pressure dissolution,dissolution,cementation and metasomatism.The pore structure of the reservoir can be divided into 4 types: the first type of low discharge pressure and small pore throat type II,low discharge pressure and pore throat type,class III ranked flooding pressure and pore throat type IV high discharge pressure and micro pore throat type,with class II low displacement pressure as the main type of fine throat.The controlling factors of reservoir development are deposition,diagenesis and structural fracture.The favorable reservoir in subaqueous distributary channel,the cementation of authigenic siliceous,feldspar and calcite cementation and compaction is the main factor leading to poor reservoir properties,laumontite,feldspar and lithic dissolution fissures,effectively improve reservoir performance.On the basis of high quality reservoir evaluation,the parameters of sandstone thickness,porosity,permeability,displacement pressure and pore structure type are taken into the evaluation system,and the comprehensive evaluation criteria of reservoir are established.The reservoirs are divided into three types: type I high quality reservoir,II type general reservoir and third type differential reservoir,among which type I high quality reservoir should be taken as the key exploration and development area in the future.