Assessment On The Geothermal Resources In Qiqihar Nanyuan Development Zone,Heilongjiang Province

Geothermal resources,due to its characteristics like environmental-friendly,low carbon discharge,recyclable,abundant reservoir,intensive distribution,stability and accountability,have attracted increasing attentions.This paper collected hydrological,climatological,geological and geothermal data in the research area,then conducted analysis,combing,categorization and comprehensive investigation of collected materials and mainly analyzed the geophysical prospecting,drilling and hydrological data within the research area.The paper characterized burial conditions,physical properties,heat source categories,cap rock features and passageways of thermal reservoirs as well as the hydro-chemical features of geothermal fluid within the research area.The article adopted the geothermal reservoir method and model analysis method stated in?Gelogic exploration standard of Geothermal Resources??GB11615-2010?to compute amounts of geothermal resource storage and exploitable geothermal resources,then conducted scale grading of geothermal fields.After that,the paper analyzed the water quality testing report and isotope testing report of QR1 well within in the research area,deduced forming time and source of thermal fluid,then carried out quality evaluation of geothermal fluids in a process described in?Gelogic exploration standard of Geothermal Resources??GB11615-2010?,and conducted assessments of exploitation,utilization and protection of geothermal resources.From the operational QR1 well in the research area,the thermal reservoir cap rocks were identified as a thick mudstone strata of Cretaceous Sifangtai Group and Nenjiang Group,while the heat sources were mainly the heat emitted from radioactive element decay within granites widely distributed in mantle heat flow and base areas;the fracture was the passageway of thermal fluid,with main heat reservoir as Cretaceous Yaojia Group,Qingshankou Group and Quantou Group,lithology of which mainly included grey particle-containing siltstone,siltstone,fine sandstone and medium-grained sandstone.The paper employed geothermal reservoir method to conduct calculation and determined 1.31×10⁹m³ of geothermal fluid reservoir,2.11×10¹⁷J of heat reservoir,including 4.66×10⁷m³ of flexible reservoir and 7.52×10¹⁵J of heat reservoir,1.26×10⁹m³of volume reservoir and 2.03×10¹⁷J of heat reservoir.The exploitable amount of geothermal fluid was determined to be 2304m³/d.The study involved two wells with1152m³/d of single well hydraulic discharge and 36?of well top temperature.The research area had 3.62MW of exploitable heat energies;the geothermal field was categorized as small size.The result of research area geothermal fluid quality evaluation suggested that:the research area had 8.5 of geothermal fluid pH,2546.515mg/L of mineralization degree,85.56 mg/L of total hardness,Cl·HCO₃-Na of type of hydrochemistry.Iodine concentration in geothermal fluid had reached a mineral water level and contained medial implications;water temperature had reached the level of warm mineral water;the fluid was not suitable for domestic use or directly as natural mineral water for drinking;the geothermal fluid included small amount of boiler scales,belonged to hard precipitant water,sparkling,non corrosive,not suitable for being directly used in boilers.The research area has a good economic potential of geothermal resources and is relatively suitable for exploitation.Geothermal resources could be applied in medical care,shower,heating,green house,cultivation,etc.For discharging of tail water,those that have been directly used could be discharged after treatment,and those that were used indirectly could be discharged through recirculation.