Abnormal Geothermal Characteristics And Geological Control Factors Of Pingdingshan No.8 Mine

Pingdingshan mining area is an area with abnormal geothermal.As the depth of excavation increases,many well fields are seriously affected by heat injury that caused quite negative impact on coal mining work.This thesis takes Pingdingshan No.8 mine in Henan Province as the research object.Based on the collection of geological exploration data,borehole temperature measurement data and mine production data,the distribution characteristics of the geothermal field in the research area was analyzed,the influence of geological factors on the geothermal field was discussed.This thesis clarified the formation mechanism of the abnormal geothermal field and carried out the thermal control geological model of the research area.This research provides a reference for the prevention and control of heat injury in the process of coal resources exploration and development,as well as the evaluation,exploration,and development of geothermal resources in similar mining areas.There are differences in thermal conductivity and radiogenic heat production of different type of rocks in Pingdingshan No.8 mine.The thermal conductivity of coal is the lowest in coal measure strata,and that of other clastic rocks is positively correlated with silicon content,while that of Cambrian carbonate rocks is higher,which is related to the high thermal conductivity of calcite and dolomite.The radioactive heat production of Permian clastic rocks is relatively high in the area,while that of coal and Cambrian rocks is obviously lower,which is closely related to the shale content of the rocks.The calculation value of the geothermal heat flow range from 65.74 to 78.31m W/m~2 in Pingdingshan No.8 mine.The uplift of tectonic basement in the mining area is the main reason of the high heat flow,while the radiogenic heat flow from coal measures is only about 1.9%of the total heat flow.Base of the difference of thermal conductivity of upper and lower strata,the main structure Likou syncline and Guozhuang anticline led to the redistribution of geothermal flow,presents a characteristics of high heat flow in anticline and low in syncline.This law is also reflected in the geotemperature gradient.The average geotemperature gradient range from 2.22 to 4.34?/hm in the research area,and the high temperature anomaly area above 3?/hm is mainly distributed in the south of the mine because of fold structures.In addition,the high temperature anomaly area of the No.8 mine is related to the groundwater activity caused by faults very closely,which is obviously reflected in the borehole geotemperature measurement curves.Analyze by synthesis,the geological thermal control model of the research area characterize by the high geothermal flow caused by tectonic basement uplift and deep thermal storage in the whole mining area.And the heat flow gathered in anticline under the control of fold structure,which formed the basic distribution pattern of geothermal field.Cambrian limestone water recharged from distant source is led up by faults after deep thermal circulation,thus regional high temperature anomaly in the south of the No.8 mine was formed.There are 52 figures,11 tables,173 references in this thesis.