地层水含盐度对生物气运聚成藏的作用  

EFFECT OF THE SALINITY OF FORMATION WATER ON BIOGAS MIGRATION,ACCUMULAT ION AND RESERVOIR FORMATION

作　　者：李本亮[1] 王明明[1] 冉启贵[1] 彭秀丽[1] 张道伟 王金鹏 

机构地区：[1]中国石油勘探开发研究院廊坊分院天然气地质所 [2]中国石油青海油田分公司勘探开发研究院

出　　处：《天然气工业》2003年第5期16-20,共5页Natural Gas Industry

摘　　要：柴达木盆地三湖地区受南缘昆仑山冰雪溶水的补给 ,地层水从南向北运移 ;由于剧烈的蒸发作用 ,地层水含盐度北斜坡最高。北斜坡泻水—汇水区高盐度条件下生物菌的活跃程度受到抑制 ,影响游离气垂向运聚成藏的资源量供给 ,中央凹陷及其南部低盐度条件下更适宜生物气的生成。生物气在地层水中的溶解度随盐度的增高而降低 ,南缘低盐度水中饱含的生物气经地层水从南向北携带 ,在北斜坡高盐度条件下大量游离出来。三湖地区早成岩阶段的泥岩盖层虽然不能成为传统意义上的盖层 ,但是实验测试证明该泥岩饱和高盐度地层水时 ,其突破压力增加约 10 0倍 ,封盖性能大大提高 ,有效地保存了北斜坡游离相生物气。研究显示生物气总体上具有向北斜坡以水溶气横向运聚的特征 ,也暗示了北斜坡气源补给充足 ,具有满坡含气的巨大勘探潜力。文章结合生物气藏本身的发育特征和三湖地区的水文地质条件 。At Sanhu region ,formation water moves from so ut h to north because of the recharge of the ice snow dissolved water coming from Kunlun Mountains in the south margin of Chaidamu Basin.The salinity of formatio n water in the north slope of the basin is the highest because of strong vapouri zation.The activity of biological bacteria is restrained under the condition of high salinity at the discharge catchment area in north slope,which influences t he vertical migration,accumulation and reservoir formation of free gas.The bioga s is more suitable for being generated under the condition of low salinity in th e central sag and on the south of the sag.The solubility of biogas in formation water decreases with the increase in salinity.The biogas saturated by the format ion water with low salinity in the south margin moved away from south to north,t hen separated out under the condition of high salinity in the north slope.Althou gh the shale caprock at early diagenetic stage at Sanhu region can't be thought as the traditional one,through experimental test it was proved that when the sha le was saturated by the formation water with high salinity,its displacement pre ssure increased by 100 times,by which the free biogas was effectively preserved in north slope owing to its sealing property's being greatly raised.Through rese arch it is shown that the biogas is of the feature of the lateral migration to t he north slope in a state of water soluble gas,which hints that the gas source is sufficient in the north slope,so it has huge exploration potential because of gas' being preserved everywhere.In combination with the developing characterist ics of biogas reservoirs and the hydrogeological conditions at Sanhu region,it i s thought in the paper that the biogas in a state of water soluble gas was late rally migrated for a far distance firstly,then the vertical migration,accumulati on and reservoir formation of biogas in a state of free gas occurred.ingpreservede

关 键 词：地层水 含盐度 生物气 运聚成藏 水溶气 溶解度 柴达木盆地 三湖坳陷 

分 类 号：P618.13[天文地球—矿床学] TE12[天文地球—地质学]