鄂尔多斯盆地高电阻率水层的成因分析  

On Genesis of High Resistivity Water Formation in Erdos Basin

作　　者：周荣安[1] 焦创赟[1] 李志伟[1] 郭清娅[1] 

机构地区：[1]长庆油田勘探开发研究院,陕西西安710021

出　　处：《测井技术》2005年第4期333-336,共4页Well Logging Technology

摘　　要：鄂尔多斯盆地属典型的特低渗透率油田,在存在大量因储层岩性发生变化而形成的低电阻率油层的同时,同样也存在因储层岩性发生变化而形成的高电阻率水层.以延长组的长3～长8储层为典型代表,其储层特点是在同一储层、水层和油层的电性十分接近,甚至好于油层,致使油层计算的含油饱和度明显偏高.经过对大量岩心的细致观察和对各种化验资料的分析认为,造成高电阻率水层的主要原因是由于储层岩石颗粒细,分选差,含有大量的粉末状物质,正是这些物质堵塞了储层的孔隙喉道,连通的孔隙变成了孤立的孔隙,使储层电阻率增加.这种情况表现为2种,即当储层胶结疏松时,表现为水层;当储层胶结致密时,表现为干层.由于这些高电阻率水层的广泛存在,严重影响了石油勘探和开发,使测井解释常常出现失误,并给测井解释带来了又一个难题.Erdos basin is a typical super-low resistivity oilfield where there are great quantity of low resistivity oil zones and water zones both resulted from variations of reservoir lithologies. Chang3-8 groups are representative of the oilfield. In these groups, resistivities of the same reservoir, water zone and oil zone are almost approximate, and the resistivities in the zones are even higher than that in the oil zone so that the calculated oil saturation in the oil zone is obviously higher. A lot of close observations of the cores and various lab testing data indicate that the existence of higher resistivity water zone is due to small or fine rock grains with poor sorting and quantities of powered substances, all these substances have blocked pore throats of the reservoirs so that the connected pores have become the independent pores, thereby increasing the reservoir＇s resistivity. There are two kinds of such cases. When the reservoir is unconsolidated, it is water zone; when consolidated, it is dry zone. These widely existing higher resistivity water zones seriously affect petroleum exploration and development, and cause difficulty for log interpretation.

关 键 词：测井解释 高电阻率水层 孔隙结构 洗油 孔隙度 渗透率 鄂尔多斯盆地 

分 类 号：P631.130.2[天文地球—地质矿产勘探]