基于多参数定量评价的低渗透砂岩成岩相划分——以鄂尔多斯盆地张韩地区长2_1储层为例

Diagenetic facies classification of low permeability sandstone based on multi-parameter quantitative evaluation: taking Chang 2_1 reservoir of Ordos Basin as an example

为探索定量划分成岩相的方法,以鄂尔多斯盆地张韩地区长21储层为研究对象,依据大量的化验分析资料,从成岩作用强度参数、孔隙发育程度参数的角度出发,建立适用于研究区的成岩相定量划分标准,阐述了不同成岩相的特征差异。结果表明:研究区长21储层岩性为岩屑长石砂岩和少量长石砂岩,压实率中等为主,含少量弱和强压实;胶结率中等含量最高,局部发育弱和强胶结;溶解率中等—强,分布少量弱溶解。基于成岩作用参数和孔隙发育程度参数的定量对比评价,考虑孔隙的组合关系和黏土矿物类型,划分出5种成岩相。不同成岩相特征差异大,弱—中等压实绿泥石胶结-粒间孔+溶蚀孔相的孔隙最发育、孔喉配置关系好、物性好、单井产量高,是最有利的成岩相带。

In order to explore the quantitative classification method of diagenetic facies, based on a large number of test data,diagenesis intensity parameters, and pore development degree perspectives, quantitative classification standard suitable for the studied area is established. Taking the Chang 21 reservoir of Ordos Basin as an example, the characteristics differences of diagenetic facies have been elaborated. The results show that lithology is lithic arkose and small amounts of feldspar sandstone in Chang 21 reservoir with the main medium compaction, few weak compaction and strong compaction; main medium cementation, and few weak or strong cementation; medium to strong dissolution, and few weak dissolution. Five kinds of diagenetic facies are classified considering the combination relations of pore and clay mineral type on the basis of quantitative comparative evaluation of diagenesis and pore development degree parameters. There are large differences of characteristics in different diagenetic facies.Weak to medium compaction chlorite cementation, intergranular pore＋dissolved pore facies is the most favorable diagenetic facies because of the developed pore, good relationship between pore and throat, good physical property, and high well production.