摘要
以辽中凹陷A21构造A21-2井为例,分析了沙四段储层自生绿泥石产状、富集因素及对储层物性的影响,结果表明:沙四段储层自生绿泥石分为2期,即早期包壳状或孔隙环边状绿泥石和晚期孔隙充填绿泥石,其中晚期孔隙充填绿泥石含量较高。富火山岩岩屑中铁镁质矿物的早期水解、微咸水湖泊的三角洲前缘环境和超高压封闭成岩环境是沙四段储层自生绿泥石富集的主要因素。早期包壳状绿泥石对石英加大生长有抑制作用,但由于沙四段储层为封闭的超压系统,SiO2仍以大量微晶石英形式沉淀,所以储层孔隙度与自生绿泥石含量相关性不明显;晚期孔隙充填自生绿泥石相对发育,增加了孔隙的比表面积,使孔喉复杂化、细小化,对沙四段储层渗透率损害较大,所以储层渗透率与自生绿泥石含量呈弱负相关关系;沙四段储层所表现的强酸敏性与储层富含自生绿泥石密切相关,建议在对储层进行酸化处理时加入铁螯合剂和除氧剂,以降低储层强酸敏性对油气层的损害。
In the case of Well A21-2 in A21 sruc- ture, Liao Zhong sag, authigenic chlorite occur- rence, enrichment factor and its impacts on reservoir petrophysics are analyzed in Member 4 of Sha- hejie Formation. The results have shown that there are two stages of authigenic chlorite in the Member 4 reservoir, i.e. earlier grain-coating or pore-lining chlorite and later pore-filling chlorite, with the later one higher in content. Several fac- tors, such as early hydrolysis of mafic minerals in volcanic detritus, delta front environment in a brackish lake and a closed and over-pressured dia- genesis system, are the keys of authigenic chlorite enrichment in the Member 4 reservoir. The earli- er grain-coating chlorite has inhibited some quartz overgrowth, but SiO2 can still precipitated as a lot of microcrystalline quartz because the Member 4 reservoir is a closed and over-pressured system, making the correlation between porosity and chlo- rite content in the reservoir be not obvious. The later pore-filling chlorite has relatively well devel- oped, which increase specific surface area of pores and make the pore throats be complicated and more tiny, causing great damage to permeability of the Member 4 reservoir. As a result, there is a weak negative correlation between permeability and the content of authigenic chlorite in this reser- voir. In addition, the strong acid sensitivity of the reservoir may be closely related with the high con- tent of authigenic chlorite, and it is suggested that the iron chelating agent and deoxidant should be added when acidizing the reservoir, in order to re- duce the harm of strong acid sensitivity to hydro- carbon zones.
出处
《中国海上油气》
CAS
北大核心
2012年第5期11-15,共5页
China Offshore Oil and Gas
基金
国家科技重大专项"国家近海大中型油气田形成条件及勘探技术(编号:2011ZX05023-001-004)"部分研究成果
关键词
自生绿泥石
产状
富集因素储层物性
沙四段辽中凹陷
authigenicment factor
reservoirShahejie Formation Lichlorite
occurrence
enrich-petrophysics Member 4 ofao Zhong sag
