Reservoir Characteristics Of Chang4+5Oil Layer Group And Their Analysis Of Controlling Factor In Zhenbei Area

Based on the research and acknowledge of predecessor for Yanchang oil layergroup in Ordos basin,this master degree thesis takes great research on the Chang4+52and Chang4+51sublayer of the Chang4+5oil layer group.This research analyses thecharacteristics of lithology,the lithogenesis,the type of accumulate and the majorcontrol factor of Chang4+5oil layer group in Zhenbei area,Ordos basin by the waywhich observe the cast flake and use the routine measurement.At last I obtain thefollowing results and understanding:1.I make fully use of the rich date of the light mineral,the heavy mineral and thedebris to analyses the orientation of the provenance.Then I think Zhenbei area wasaffected by the provenance of the southwestern and the the west and located in theconvergence zone which control by many depositional system.The provenance ofeach period was inherited anyway.2.With the observe and description of the drill core,flake and SEM I research theprecipitation facies of Chang4+5sector systematic.The result shows that Chang4+5oil layer group mainly composed of the delta regime of the anastomosing streamwhich covers deltaic plain microfacies and deltaic front microfacies.The deltaic plaindistributary channel and deltaic front subsea distributary channel was the majorreservoir sand body.3.The major type of the reservoir rock of the Chang4+5oil layer group inZhenbei area was between thin and middle size lithic arkose.The main type of thepore space was intergranular space and arcosic dissolved pore and intergranulardissolved pore was lesser.the pore rate of the surface was increased alone with theincrease of Chang4+5oil layer group depth vertically.The relationship between theprimary intergranular space and the content of the quartz was direct correlation.Therelationship between the primary intergranular space and the content of the calciticcementation and the gyulekhite was inverse correlation.The relationship between thefeldspar dissolved pore and the content of the feldspar was direct correlation.4.The analyses of the physical property of the reservoir feature show that theaverage porosity and permeability of the Chang4+51oil sector are large than theChang4+52oil sector.the construction of the permeability of the Chang4+51oil sector is better than the Chang4+52’ because of the high expulsion pressure and the littleradius of the pore throat.There is4type of the pressure curve of the capillary pore.Thetpye Ⅰ and Ⅱ belong to Chang4+51oil sector and the tpye Ⅱ and Ⅲ belong toChang4+51oil sector.5.It shows that among the several kinds of pores in Chang4+5oil layer group,feldspath dissolved pore occupies first place; intergranular dissolved pore comessecond. This layer group has two types of lithogenesises: one is constructionallithogenesis which contains denudation and chlorite argillan neogenesis; the other oneis destructive lithogenesis, it also includes secondary enlargement of quartz andfeldspar, mechanical compaction and carbonate cementation, the last two lithogenesisplay the main role in causing the sandstone primary pore loss in this area.6.Based on these lithogenesis, build5types of lapidofacies of Chang4+5oillayer group in Zhenbei area. It is carbonate cement faces、kiesel—illitic cemented、illitic cemented—feldspar dissolved pore phase、kaolinic thin corrosion phase andchlorite rim residual pore phase.The Chang4+5oil layer group reservoir was betweenthe late period of the early of the diagenetic stage A and the early period of the late ofthe diagenetic stage B.7.The Chang4+5oil layer group accumulate ability in Zhenbei area was affectedby the sediment microfacies、the lithogenesis and the diagenetic facies factors.Theprofitable sand body type of the sediment microfacies is the deltaic plain distributarychannel and deltaic front subsea distributary channel was the major reservoir sandbody.The favorable diagenesis and lapidofacies consist of feldspar dissolved porephase、kaolinic thin corrosion phase、chlorite rim residual pore phase.