准噶尔盆地车排子地区吐谷鲁群储层成岩作用与孔隙演化

准噶尔盆地车排子地区是油气勘探的重点区块。通过岩心观察、薄片鉴定,对车排子地区下白垩统吐谷鲁群储层岩石类型、孔隙类型、储集物性、成岩作用及孔隙演化进行研究。结果表明储层岩石类型主要为长石石英砂岩、岩屑长石砂岩及长石岩屑砂岩,颗粒较细,分选、磨圆较好,结构成熟度较高。储集空间为粒间孔、扩大粒间溶孔、粒内溶孔及溶缝,其中粒间孔占主导地位。岩心样品的孔隙度主要为5%~30%,渗透率为(0.01~1 100)×10-3μm2,大多数属于中低孔、中低渗—特低渗储层。研究区白垩系埋藏较浅,地温低,成岩作用较弱,主要类型有压实作用、胶结作用、交代作用和溶解作用,处于成岩作用早期,且油气早期充注对吐谷鲁群储层成岩作用及孔隙演化具有较大影响。车排子地区吐谷鲁群储层勘探目标应以孔隙度18%的优质储层为主。

Diagenesis and pore evolution of Cretaceous Tugulu Group reservoir in Chepaizi area,Junggar Basin,China

The Chepaizi area in Junggar Basin is the main region to explore oil and gas.Based on core observation and thin section identification,this paper studies the rock type,pore type,reservoir properties,diagenesis and pore evolution of the Cretaceous Tugulu Group reservoir in the Chepaizi area.The results show that the main rock types of the reservoir are the feldspathic quartz sandstone, lithic feldspathic sandstone and feldspathic lithic sandstone whose grains are fine,well sorted and rounded,and high-maturity structure. The main pore types are intergranular pore, expanding intergranular dissolved pore,intragranular dissolved pore and dissolved fracture.Among them,the intergranular pores occur most frequently.The porosity of the reservoir is 5% ~ 30% and the permeability is (0.01~1100)×10 -3 μm2 .The reservoirs are most low-hole and hypotonic-ultra-low-permeability reservoirs.In study area,Cretaceous is shallow burial layer,the temperature is low,and the diagenesis is weak.The main types of diagenesis are compaction,cementation,metasomatism and dissolution,and all in the early stage,and the early filling of oil and gas has a great impact on the Tugulu Group diagenesis and porosity evolution.In the Chepaizi area,the exploration target of the Tugulu Group reservoir should be the high-guality reservoir with >18% porosity.