塔里木盆地雅克拉地区氦气资源评价与成藏模式

Helium resource evaluation and enrichment model in Yakela area,Tarim Basin

塔里木盆地北部雅克拉地区发现具有开采价值的含氦气田,其中古生界氦气的平均含量为0.31%,是氦气资源量最丰富的层位,高于氦气工业生产标准,但其氦气资源潜力和成藏模式尚不清楚。基于雅克拉地区14口钻井的自然伽马能谱测井资料,对雅克拉地区古生界氦气资源生成量进行了定量评估,并结合成藏要素进行综合分析,根据氦气的运聚过程及载体特征,总结出氦气成藏模式。结果表明:雅克拉地区古生界平均生氦潜量为2.37×10^(-10)cm^(3)/g,氦气生成总量为3.22×10^(9)m^(3)。生氦潜量最高的区域位于沙15井附近区域,其次为沙49井附近区域,从沙5井至沙49井的呈带状展布的狭长地带是生氦主力。区域内古生界沉积岩系供给含氦气藏的氦气量可高于天然气藏中的氦气总量,沉积岩系可为有效氦源岩,生成氦气以主要形成于加里东—海西构造期的断裂、裂缝为运移通道,在地下水和天然气的协助下持续运移,以古老地层水运移聚氦模式、天然气沿古老储层运移聚氦模式进行聚集成藏,上覆3套厚度较大的泥岩层、膏岩层,可对气藏有效的封存保护。

A good prospect of helium resources have been found in Yakela area in the north of Tarim Basin.The previous research data have shown that the average content of helium in Paleozoic is 0.31%,which is the stratum with the most abundant helium resources and is higher than the industrial production standard of helium,but the potential of helium resources generation and the reservoir enrichment model in this stratum are still unclear.Based on the natural gamma spectrum logging data of 14 wells in the Yakela area,the helium resource generation of the Paleozoic in the Yakela area was quantitatively evaluated,and combined with the comprehensive analysis of the accumulation factors,the helium enrichment model was summarized according to the helium migration,accumulation processes and carrier characteristics.The results indicate that the average helium generation rate of the Paleozoic in Yakela area is 2.37×10^(-10)cm^(3)/g and the helium generation is 3.22×10^(9)m^(3).The area with the highest helium generation rate is predicted to be located near Well Sha 15,followed by the area near Well Sha 49.The main helium generation area is the strip stretching from Well Sha 5 to Well Sha 49.The amount of helium supplied by the Paleozoic sedimentary rock series to the helium-bearing reservoir in the region is higher than the total amount of helium in the natural gas reservoir,and the effective helium source rock can be the sedimentary rock series.With the faults and fractures mainly formed in the Caledonian-Hercynian tectonic period as the migration channels,helium continues to migrate with the help of groundwater and natural gas,and the helium is transported and accumulated by two models,including helium enrichment by ancient formation water moving upward along the fault and helium enrichment in the process of natural gas migration along ancient reservoirs,with three sets of thick Mesozoic and Cenozoic mudstone or gypsum layers being effectively sealed and protected above.