Research Of Geothermal Resources On Hot Dry Rock In North Songliao Basin

As one of the geothermal resources,Hot Dry Rock has the characteristics of rich reserves and the heat energy storage concentrated.In China,the research,development and utilization of Hot Dry Rock started relatively late,the existing work mainly stays in theory and research stage mainly for Hot Dry Rock's exploration and evaluation.Songliao Basin is famous for containing a large continental sedimentary basin,it is rich in oil,gas and geothermal resources.So far,research of geothermal resources in north Songliao Basin are mainly concentrated in shallow,low-temperature geothermal resources,the research of Hot Dry Rock for depth is still in the blank.In this paper,through the research of Hot Dry Rock in north Songliao Basin,improved the theory of exploration and utilization of geothermal resources in north songliao basin.As the foundation of exploration research results and oilfield exploration data in Songliao Basin,the paper analyzed the characteristics of the geothermal field in Songliao Basin.the terrestrial heat flow is 44.83?95.04 mw/m2 in north Songliao Basin,there are two high-value areas,which are located at the central depression and the junction of the three one-level tectonic zone such as the central depression,southeast uplift and northeast uplift.temperature gradient with depth showing a tendency to increase gradually reduced in the vertical in North Songliao Basin;geothermal gradient in the plane distribution range of 2.0?6.0?/100 m,with an average of 4.0 ?/100m,showing a trend of decreasing from the center to the edge of the basin,high geothermal gradient area consistent with the high terrestrial heat flow area.the region of 3 km depth of formation temperature over 150 ?has a total area of about 1680 km2,it can be seen that north Songliao Basin has a good background of forming geothermal resources,it is a favorable area for Hot Dry Rock exploration.Distribution of Hot Dry Rock in north Songliao Basin is relatively concentrated,mainly distributes in central,southern and southeast of the study area,the depth of 150 ?isothermal surface of these areas are basically within 5km,and can reach 7km at the edge of the basin,this is not conducive to the development of dry hot rock.The heat source of heat Hot Dry Rock in north Songliao Basin is given priority to deep mantle heat,accounting for about 60.2%,heat production of radioactive elements account for about 38.4%,mainly concentrate in the upper crust.The heat energy in the reservoir mainiy in the form of heat conduction transfer from the deep heat source,in some areas,the lithosphere fracture,broken shells and converge to spin off with the shovel type of basement faults,provides a good channel for the thermal convection,can form a transfer mode based on thermal convection.The formation and distribution of Hot Dry Rock in north songliao basin is affected by the deep crust and mantle structure,fracture,magmatism,basement and cover,and hydrogeological conditions.The depth of north songliao basin is 3?10km,Total geothermal resources of Hot Dry Rocks with temperature greater than 150 ? is 2190.5 X 1020J,approximately is equivalent with 7.45073 trillion tons of standard coal.If the recoverable lower limit is 2%,the recoverable amount of Hot Dry Rock geothermal resources within the the scope of 6 km in north songliao basin is 7.4 X 1020 J,approximately is equivalent with 253.3 trillion tons of standard coal,its reserves are abundant visibly.The geothermal reserves abundance of Hot Dry Rock in north Songliao Basin distribute from 1065.4 ×1012kJ/km2 to 4783.5 ×1012kJ/km,the total area with geothermal reserves abundance of Hot Dry Rock?4000 X 1012 kJ/km2 is 3360km,mainly distribute in Chaoyanggou terraces and southern Daqing Changyuan.Enhanced Geothermal Systems form geothermal reservoirs using artificial methods,artificial geothermal systems is mining heat from the Hot Dry Rock.In the construction of artificial geothermal reservoir in enhanced geothermal systems,hydro-inspired methods is also largest used currently.Due to be similar with low porosity and permeability reservoirs and shale gas exploration,so we will introduce sew mesh fracturing technology into the construction of artificial geothermal reservoir in enhanced geothermal systems.If the net pressure on the value in the construction process can achieve the sum of horizontal principal stress difference and the tensile strength,and new cracks you can be formed on the basis of original cracks,thereby forming a seam network system.In a study of mining enhanced geothermal systems,the selection of targets was taken the principle of the underground to obey ground,and the numerical simulation was constructed on this basis.When constant flow of the injection wells was 30kg/s,formation fluid leakage rate was 25%,reservoir temperature was 200 ?,the temperature of horizontal section of the production well from 0 to 13 years was in a stable state,was 200 ?;the temperature of extraction wells after 13 years began to decrease,the temperature of extraction wells to the first 20 years lowed to 145 ?.Artificial heat reservoir was mined by 97.8 X 1012kJ calories in 20 years,approximately was equivalent with 33.2 × 104 tons of standard coal,it can reduce carbon dioxide emissions as 86.984 × 104t,sulfur emissions as 0.283 × 104t,nitrogen oxides emissions as 2.456 × 104t.Due to the high temperature,and to avoid wasting energy,mined ground water can be divided into four cascade:the geothermal water with temperature?90 ? can be used for geothermal power;the geothermal water with temperature of 50?90 ? can be used for building heating in winter and air conditioning in summer,drying,etc.;geothermal water with temperature of 45?50 ? can serve as a spa bath,and living hot water,etc.;geothermal water with temperature of 25?45 ? can be used for geothermal greenhouse cultivation,aquaculture and geothermal heat pumps.This paper shows that the geothermal resources of Hot Dry Rock in the north Songliao Basin has great potential,exploiting Hot Dry Rock by use of enhanced geothermal systems in the north Songliao Basin is feasible,this study on development and utilization of deep geothermal resources in the future has guidance and reference significance.