玉门老君庙油田M层低渗透块状砂岩油藏开发沉积相

SEDIMENTARY FACIES OF THE LOW PERMEABILITY,MASSIVE SANDSTONE M RESERVOIR,LAOJUNMIAO OILFIELD,YUMEN,GANSU PROVINCE

甘肃玉门老君庙油田的 M 层是上第三系的低渗透率厚层块状砂岩油藏。为了提高采收率,通过细分砂岩岩性,查清岩电关系和分析物性资料,建立了沉积相模式、成岩作用模式、非均质性模式和液体流态模式。位于 M 层底部的 M_1以冲积扇相为主,岩性粗,由薄的正韵律层叠置而成,碳酸盐含量高,渗透率低,且垂向变化幅度小,为块状低渗透油层。中部的 M_2为辫状河的河床亚相,岩性粗细不等,碳酸盐含量和渗透率的变化大,由高碳低渗的主河槽正韵律层与低碳高渗的砂坝交互韵律层组成,油水在地层中作层状和似层状流动。顶部的 M_3为辫状河越岸泛滥亚相,岩性细,碳酸盐含量低,渗透率高,以厚的砂岛交互韵律层为主,夹以薄的汉河槽正韵律层,属块状高渗透油层。

The M-reservoir,Laojunmiao oilfield,Yumen,Gansn province,China,is a low-permeability upper Tertiary massive sandstone reservoir,In order to enhance the oil recovery,models of sedimentary facies,diagenesis,heteroge- neity and patterns of liquid flowing are established by means of subdivision of sandstone lithology in detail,integrated by a study of litho-log relationship and an analysis of petrophysical data. M_1,the lower portion of M-reservoir,is mainly of an alluvial fan facies, and is composed of coarse,repeated upward fining cycles with high content of carbonate and low permeability,the vertical variation of the permeability ra- ther small.It is a typical low-permeability massive reservoir. M_2,the middle portion,is of braided stream channel subfacies.Its litho- logy varies from coarse to fine grain,and the variation in carbonate content and permeability is rather remarkable.There are both the upward-fining cy- cles of major channel with high carbonate content and low-permeability and the interbedded cycles of sandbar with lower carbonate content and higher per- meability.Theliquids in M_2 move in a sheet-like and quasissheet-like manner. M_3,the upper portion,is of overbank braided river flooding fades.Its is mostly fine in structure.Carbonate content is low and permeability is high. Its vertical sequense is mainly characterized by.rhythmic cycles of sandisland. intercalated by thinly upward-fining cycles of minor channel.It is a high pe- rmeability massive reservoir.