Researches About Dense Reservoir Characteristics And Comprehensive Evaluation Of Fuyu Reservoir In Sanzhao Sag

Fuyu reservoir in Sanzhao sag has experienced preparatory reconnaissance andevaluation. Fuyu reservoir is currently in the stage of experimental research. For the effectiveproduce of Fuyu reservoir difficult reserves， we have carried out fine geologic study.Because of the complex fault systems， the forecast difficulty of channel sand body and oiland gas enrichment zone recognized more difficultly， development experiment has notyielded significant results. In this paper， guided by high resolution sequence stratigraphy，reservoir sedimentology and seismic sedimentology， we have systematicly researched thedeposition background and provenance direction of Fuyu reservoir in Sanzhao sag. Fromsedimentary facies researches in full district to the fine dissection in typical blocks， we havecarried out subzone correlation in full district and figured the sand body distribution. We haveanalyzed reservoir microscopic pore types and structure parameters， classified themicroscopic pore structure， analyzed the relationship between physical characteristics，diagenetic evolution. With logging data and seismic data， we have predicted sand bodydistribution in the full district according to seismic sedimentology， and classified thereservoir according to macroscopic and microscopic features， and predicted rich oil zones inFuyu researvoir and ultimately pointed out the next goals of drilling and development.According to the analysis of heavy minerals， formation thickness and sand bodydevelopment， Fuyu reservoir in Sanzhao sag has two provenance directions， one is fromsouthwest， the other is north. The north provenance direction is divided for two delta， thesouthwest is divided for four water branches. The North-South two provenance directionsconcoursed in Xujiaweizi oilfield. The researches about high resolution sequence stratigraphyindicate that Fuyu reservoir in Sanzhao sag can recognize out one full medium-term baselevel cycle， thirty-five ultrashort-term base level cycles， the isochronal formationframework has been established， and subzone correlation of Fuyu reservoir has been carriedout in Sanzhao sag. According to the researches about paleontologic evidence， core andlogging data， Fuyu reservoir developed fluvial shallow dominated delta. By fine anatomy ofsingle sand body， we have established two shallow delta depositional models in Fuyureservoir: branched， branched and braided. The microscopic characteristics of Fuyu reservoirhas been carried out systematic study. The Fuyu reservoir rocks are moderately sorted，mainly aphanocrystalline feldspathic litharenite， lithic arkose and siltstone. Reservoir poretypes are mainly intergranular dissolved pore， intragranular dissolved pore， grainulardissolved pore， argillaceous micropore and micro fracture pore. According to the microcosmic pore structure parameters， four types of microscopic pore structure have beendivided， the Fuyu reservoir is poor， mainly with the third and fourth type of microscopicpore structure. Applied NMR technology to research reservoir fluid saturation， classificatedthe reservoir according to the test results. Reservoir is mainly at the early and middle latediagenetic stage， and is the typical low porosity and ultra-low permeability reservoir.According to the reservoir evaluation standard，Fuyu reservoir in Sanzhao sag can be dividedinto two basic types: the ultra-low permeability reservoir and ertra-low permeabilityreservoir， the former is mainly with ultra-low permeability， medium pore and fine throatreservoir， the latter can be further subdivided into two types of reservoir: fine throat withmiddle-porosity， uneven minute throat with fine porosity and uniformly micro-fine throatwith fine porosity. Integrated evaluations of Fuyu reservoir with step analysis and fuzzycomprehensive evaluation method，the reservoir is poor over all， the main type is II orIII.The distributary channel is the main sand body type， that is distributary channel andunderwater distributary channel sand body of the shallow water delta， whose distributionrange is wide. The channel sand bodies are vertically superimposed each other， horizontallydeposited into sheets， constitute the favorable hydrocarbon pore volumes. We have predictedthe rich oil zones of Fuyu researvoir in Sanzhao sag， according to the multidisciplinaryanalysis of the favorable sand body.