克拉玛依油田四_2区齐古组储层特征与评价

RESERVOIR CHARACTERISTICS AND COMPREHENSIVE EVALUATION OF QIGU FORMATIONIN NO.4-2 REGION,KARAMAY OILFIELD

克拉玛依油田四2区齐古组主要为冲积扇沉积,储层岩石类型以岩屑长石砂岩为主,碎屑成分中杂基、胶结物含量较高,成分成熟度低、结构成熟度中等。孔隙类型主要为剩余粒间孔、原生粒间孔和粒内溶孔;储层成岩作用相对较弱,碳酸盐析出是原生孔隙降低的重要因素。喉道以弯片状—片状组合类型为主,可分为4种孔喉类型:粗孔粗喉型、粗孔中喉型、中孔细喉型和细孔细喉型。储层物性为中孔—中渗类型,连通性较好。采用贝叶斯判别分析和Q型聚类分析方法对储层进行了综合评价,结果表明:G22、G23、G33小层中I、II类储层占较大比例,G32小层中IV类储层比例较大,综合分析认为,G22、G23、G33是有利的勘探目的层。

Qigu reservoir in District No. 4-2 of Karamay Oilfield is dominated by alluvial fan deposit. The reservoirrock types are dominated by lithic arkose,with relatively high content of matrix and adglutinate in the clasticcomponents,and its petrology is characterized by low maturity of components,medium textural maturity. The poretypes are mainly remaining intergranular pores,primary intergranular pores and intragranular dissolved pores. Diagenesisof the reservoir is relatively weak. Separation of carbonates is an important factor of primary pore reduction.Pore throat is dominated by flaky assemblages of curved laminar,and four types of pore throats can be divided:coarse-pore coarse throat type,coarse-pore medium throat type,medium-pore fine throat type and fine-pore finethroat type. Petrophysical properties are characterized by medium porosity and medium permeability,with relativelygood communication. Bayes principle is used to identify and analyze the parameters and Q-type cluster analysiswas adopted to carry out comprehensive evaluation on the reservoirs. The results show that Type-I and Type-II reservoirsin subzones G22,G23 and G33 account for larger proportion,whereas Type-IV reservoir account for largerproportion in subzone G32. Based on comprehensive analysis,it is inferred that subzones G22,G23 andG33 arefavorable target zones for exploration.