Radiogenic heat production of magmatic rock of coal measure strata based on natural gamma-ray logging in Zhuji mine field of Huainan coal field

Zhuji mine field was taken as research object to study the characteristics of heat generation rate of magmatic rock of coal measure strata in Huainan coal field and its influence on geothermal field, on the basis of the 6 208 natural gamma logging values in 36 boreholes, the average values of heat generation rate of different rocks and their standard deviation were calculated by using the relation of natural gamma(GR) and heat generation rate(A). The results show that GR values of sedimentary rocks in the coal measures is in descending order:mudstone (83.83 API), sandstone (62.23 API) and coal (34.32 API). And the GR value of magmatic rock is 103.89 API, much higher than that of sedimentary rocks. The heat generation rate of magmatic rocks is the biggest as well, its average is 1.63 μW/m³, about 3 times higher than that of coal, but because of the influence of staged intrusion of magmatic rock, its standard deviation is bigger. In general, the contribution of the rock radiogenic heat in coal-bearing srata was not big for terrestrial heat flow in Zhuji mine field, but the high generation rate of magmatic rock changed a lot the thermal structure of strata.