Resource property and exploitation concepts with green and low-carbon of tar-rich coal as coal-based oil and gas

The middle reaches of the Yellow River is an important coal rich area and the main production area of tar-rich coal.Restricted by the resource endowment characteristics that is lack of oil,less gas and relatively rich coal,it is a significant requirement for the basic guarantee for domestic energy supply security to utilize coal with the green mining,clean and low-carbon development.Realizing the coordinated development of tar-rich coal exploitation in the Yellow River Basin and eco-environmental protection is great significant to alleviate the shortage of oil and gas supply and ensure the energy strategic security in China.As a kind of coal-based oil and gas resource,the scientific connotation,particularity and key geological problems of tar-rich coal are needed to be further illustration,and the green and low-carbon development technology needs to be studied.① Tar-rich coal is occurrence in low and middle rank of coal,with generate oil,gases and semi-coke by pyrolysis.And the major characteristic is with more hydrogen-rich structure.The main composition of the semi-coke is fixed carbon,which is similar to anthracite;The gases are mainly CH4,H2,CO and hydrocarbon gases,which are considered as fuels and chemical materials;The oil is coal tar that is similar to heavy oil,which can convert to the standard clean fuel through pretreatment,hydrofining and hydrocracking.② The hydrogen-rich structure is the vital basis for tar-rich coal as coal-based oil and gas.The fundamental principle to establish the prediction model and evaluation theory of tar-rich coal is investigating the petrological and sedimentological characteristics and control laws of hydrogen-rich structure,and analyzing the mechanism of the coal-forming origin,deposition and transformation,coalification,accumulation and geological control.③ Cascade utilization and in-situ pyrolysis are important pathways to realize green and low-carbon development of tar-rich coal.The pyrolysis-gasification integration and the pyrolysis-chemical-power on the ground can realize the clean and efficient utilization of the tar-rich coal.The underground in-situ pyrolysis is expected to overcome the problem of clean and low-carbon utilization of tar-rich coal.For instance,underground in-situ pyrolysis technology uses the underground roadway to carry out coal seam segmentation,thermal insulation and sealing,and realize the underground pyrolysis and tar recovery through the in-situ heating of coal seam;The borehole in-situ pyrolysis technology can achieve heating tar recovery by injecting heat from the hot injection hole and collecting tar from the extraction hole.T artificial cracking is needed as an ancillary technique.Exploiting and managing the tar-rich coal as the coal-based oil and gas is an important direction of high quality development of coal industry in a new era.