Analyses Of Helium Phase And Accumulating Characteristics In Weihe Basin

Since the research work of the helium gas in oil exploration wells and geothermal wells of Weihe basin has been carried out, the exactly phase of helium in Weihe basin is still not clear which is soluble phase coexist in basin underground hot water or in free facies with other associated gases, and the helium enrichment characteristics also needs further research.All of these facts has affected the scientific evaluation and resource utilization prospects of helium gas in Weihe basin.In this paper, based on the study of geology, gas logging, gas analysis testing, geochemical, seismic and logging data of the Weihe basin, gas solubility characteristics, the theory of gas phase state characteristics etc to analyze characteristics of conducting system about helium source region and main helium bearing formations, the temperature variation characteristics of helium source region and main helium bearing formations, the pressure variation characteristics of helium source region and main helium bearing formations, the phase state characteristics of helium and the main associated gas phase state,and further analysis of helium enrichment characteristic in Weihe basin.Mainly achieved the following understandings:1. Associated gases in oil exploration wells and geothermal wells of Weihe basin mainly include helium gas, methane, nitrogen, carbon dioxide, etc. Based on mainly associated gas content characteristics in geothermal wells, gas logging abnormal distribution characteristics of Weihe basin, monitoring data of gas water ratio in geothermal wells of Weihe basin,and gases solubility characteristics in water which include helium, nitrogen, carbon dioxide and methane,and theory of phase determination of helium, nitrogen, carbon dioxide, it is revealed that helium gas in Weihe basin is not only a water soluble phase but also a free phase coexisting with gas symbiosis in Weihe basin.It is also proved by ws13?051?wr5?sp1?sp2 wells.2.Granite of Qinling of the southern edge of the Weihe basin area is a relatively low temperature variation, and sand mudstone area in Weihe basin is a relatively increaseing temperate variation.Helium gas dissolved in the groundwater of Weihe basin is mainly affected by temperature. Qinling piedmont band is an enriching band of dissolved helium gas.3.Helium gas source rocks of Weihe basin are mainly the granite distributed in the periphery of the Weihe basin. Granite of Qinling which mainly developed massive cracks and faults produces a better vertical conducting performance. The combination of sand and shales in Weihe basin transverse conducting performance generally better than the vertical conducting properties on the whole. Helium gas in free phase of Weihe basin is mainly affected by the pressure of the basin.The band from Qinling piedmont area to Wugong-Lintong-Huayin is the enrichment band of free phase helium gas.4. Helium gas of Weihe basin can be reduced to three enrichment bands in the plane which include Qinling piedmont belt and Qinling piedmont to Wugong-Lintong-Huayin belt and Wugong-Lintong-Huayin to Weihe fault belt. Qinling piedmont belt is the primary helium-rich area, Qinling piedmont to Wugong-Lintong-Huayin belt is the second helium-rich region, Wugong-Lintong-Huayin to Weihe fault is the belt that a relatively small amount of helium gas enriches.