Study On The Diagenesis And Reservoir In Tenggeer Formation Of Baiyinchagan Depression

Tenggeer formation was one of the important reservoir horizons in Baiyinchagan depression,it was the target reservoir horizon of the research.In this paper, studying on the diagenesis and reservoir of rocks, and the factor impacted on the the reservoir were analyzed.The problem such as distribution rule of favorable reservoir and exploration failure which the densify reservoir caused was solved.In this paper,the rock types of this area were determined by the use of ordinary thin-section identification and cast thin-section analyisis,combined with the description of rock core.There were arkose,feldspathic quartzs sandstone,lithic quartzs sandstone,lithic arkose,feldapathic litharenite and a little lithic.There were mainly arkose,lithic arkose and feldspathic quartzs sandstone in north steep slope;There were all the types of the sandstone,but there was more lithic in south steep slope.The analysis of the tectonic background of the provenances indicated that:the material was mainly derived from landmass in north steep slope,it was primarily derived the landmass provenance and recycling orogenic zone in south steep slope.Main types of diagenesis include the compaction,the pressure solution,the cementation,the dissolution,the metasomatism and the alteration,meanwhile the compaction,the cementation were more obvious,this was one of the reason that the porosity was poor; According to vitrinite reflectance, clay mineral assemblages and Eamonn in the mixed-layer smectite ratio and so on, to determine the north of the depression of the overall composition of rocks in the diagenetic phase A-B for a view and the south of rocks in the diagenetic phase A for a view.Reservoir pore space types of Baiyinchagan Depression Tenggeer formation are including original intergranular pores, enlarged intergranular pores,intragranular dissolution pores,intragranular micro-pores,moldic pores and fissures;MeanwhileThere were intergranular pores and enlarged intergranular pores in Sanghe and Xilinhaolai area,there were secondary pores caused by the dissolution and the alteration in Daerqi and Wengte area.The reservoir capacity of the fan delta front subfacies wsa better than the fan delta plain subfacies and the prodelta subfacies,there was the discrepancy in differert zone.The reservoir was better-high porosity and low permeability in Sanghe area;it was better-low porosity and better-low permeability in Xilinhaolai area;The porosity and permeability of Daerqi and Wengte area were all better-high.The analysis showed that the sandstone reservoir of the Tenggeer formation were impacted by depositional facies and the diagenesis.The reservoir of the fan delta front subfacies was the best and the fan delta plain subfacies and the prodelta subfacies was worse.As burial depth increasing,it become worse;but it was better because the secondary pores which the dissolution caused. By the above research,we could forecast the favorable reservoir.