基于自然伽马测井的淮南煤田朱集井田煤系岩浆岩生热率研究

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

为研究淮南煤田煤系岩浆岩生热率特点及其对地温场的影响,以淮南朱集井田为研究对象,基于36个钻孔内6 208个煤系岩石自然伽马(GR)测井值的基础上,利用自然伽马与生热率GR-A的关系式,计算不同岩石生热率及其标准差,结果得出,煤系沉积岩的GR值由大到小依次为泥岩83.83 API、砂岩62.23 API和煤34.32 API,岩浆岩的GR值为103.89 API,远大于沉积岩;岩浆岩的生热率也最大,平均1.63μW/m3,约为煤的3倍,但因受岩浆岩侵入分期性的影响,其标准差较大。总的来说,朱集井田内煤系岩石放射性生热对区内大地热流的贡献量不大,但岩浆岩的高生热率对岩层生热结构的改变较大。

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 the6208natural gamma logging values in36boreholes,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(83.83API),sandstone(62.23API)and coal(34.32API).And the GR value of magmatic rock is103.89API,much higher than that of sedimentary rocks.The heat generation rate of magmatic rocks is the biggest as well,its average is1.63μW/m3,about3times 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.