冷湖七号和南八仙渐新统混积岩储层特征对比分析
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摘要
渐新统下干柴沟组下段是柴北缘中部地区油气勘探的主要目标,弄清该区储层发育的控制因素是深入评价的基础。文中根据铸体薄片、普通薄片及岩屑录井等资料,对该区冷湖七号和南八仙构造的岩石学特征进行了对比分析。研究表明,该区大量发育陆源碎屑、碳酸盐、硬石膏的混合沉积,但是由于水体咸度的不同,在冷湖七号的滨浅湖混积岩中硬石膏含量较高,颗粒主要为基底式胶结;而南八仙构造地处辫状河三角洲前缘相带,因河流的稀释作用,混积岩中硬石膏体积分数很低,颗粒为孔隙式-基底式钙质胶结,原生孔喉较为发育,有利于后期酸性流体的溶蚀改造。由于2种类型混积岩的初始孔隙度及孔喉演化模式不同,最终引起2个地区含油气丰度的巨大差异。
The lower interval of Oligocene Xiaganchaigou Formation is an important prospecting object in the central areas of northern Qaidam Basin.Finding out the factors controlling the reservoir property is prospecting basis.Based on the normal thin sections,cast thin sections and drilling data,the rocks characteristics of No.7 Lenghu and Nanbaxian structure were analyzed in this paper.Study shows that the mixed deposits such as terrigenous clastic,carbonate and anhydrite are found very common in this area.But because of different salinity,the content of anhydrite is high in shore shallow lake facies peperite of No.7 Lenghu structure.Particles are mainly base type cementation.The salinity of Nanbaxian structure located in delta front facies belt is lower because of the great amounts of water input by the rivers and there is little anhydrite in peperite.Particles are mainly pore type-base type calcium cementation.The initial porosity in Nanbaxian is much higher than that of No.7 Lenghu,which is in favour of the later dissolution of acidic fluid.Because the initial porosity and pore throat evolution model for two types of peperites are different,there is great difference in the oil and gas abundance of two areas.
The lower interval of Oligocene Xiaganchaigou Formation is an important prospecting object in the central areas of northern Qaidam Basin.Finding out the factors controlling the reservoir property is prospecting basis.Based on the normal thin sections,cast thin sections and drilling data,the rocks characteristics of No.7 Lenghu and Nanbaxian structure were analyzed in this paper.Study shows that the mixed deposits such as terrigenous clastic,carbonate and anhydrite are found very common in this area.But because of different salinity,the content of anhydrite is high in shore shallow lake facies peperite of No.7 Lenghu structure.Particles are mainly base type cementation.The salinity of Nanbaxian structure located in delta front facies belt is lower because of the great amounts of water input by the rivers and there is little anhydrite in peperite.Particles are mainly pore type-base type calcium cementation.The initial porosity in Nanbaxian is much higher than that of No.7 Lenghu,which is in favour of the later dissolution of acidic fluid.Because the initial porosity and pore throat evolution model for two types of peperites are different,there is great difference in the oil and gas abundance of two areas.
引文
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[3]Mount J F.Mixing of siliciclast and carbonate sediments shallow shelf environments[J].Geology,1984,12:432-435.
[4]刘宝珺,王剑,谢渊,等.当代沉积学研究的新进展与发展趋势:来自第三十一届国际地质大会的信息[J].沉积与特提斯地质,2002,22(1):1-6.
[5]罗顺社,刘魁元,何幼斌,等.渤南洼陷沙四段陆源碎屑与碳酸盐混合沉积特征与模式[J].江汉石油学院学报,2004,26(4):19-21.
[6]马艳萍,刘立.大港滩海区第三系湖相混积岩的成因与成岩作用特征[J].沉积学报,2003,21(4):607-613.
[7]苏亚拉图,陈程,陈余平.鄂尔多斯盆地召38区块储层建构模式及其控制作用[J].断块油气田,2012,19(1):59-64.
[8]白玉彬,赵靖舟,陈孝平,等.蟠龙油田长2储层裂缝分布及油气地质意义[J].断块油气田,2012,19(1):61-64.
[9]陈延芳,刘士磊,宋章强,等.渤海中深部碎屑岩有效储层划分及勘探意义:以黄河口凹陷为例[J].断块油气田,2012,19(6):710-713.
[10]李新虎,刘东,郭媛.HSS油田H_1油层组储层特征研究[J].断块油气田,2011,18(2):150-153.
[11]胡作维,黄思静,马永坤,等.鄂尔多斯盆地姬塬地区长2油层组储层孔隙结构特征[J].断块油气田,2012,19(5):588-591.
[12]高先志,陈发景,马达德,等.南八仙构造油气成藏模式及其对柴北缘勘探的启示[J].石油实验地质,2001,23(2):154-159.
[13]王鹏,赵澄林.柴达木盆地北缘地区第三系碎屑岩储层沉积相特征[J].石油大学学报:自然科学版,2001,25(1):12-15.
[14]张锦泉,叶红专.论碳酸盐与陆源碎屑的混合沉积[J].成都地质学院学报,1989,16(2):87-92.
[15]中国科学院兰州地质所.青海湖综合考察报告[M].北京:科学出版社,1979:74-88.
[16]徐北煤,卢冰.硅质碎屑岩中碳酸盐胶结物及其对储层的控制作用的研究[J].沉积学报,1994,9(3):56-66.