枯竭页岩气藏地热开发潜力及不同闭式系统注水循环采热效率分析

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中图分类号：TE09；P314 文献标志码：A

Abstract：Deepshalegasreservoirs intheSichuan Basin posessabundant geothermal potentialsForinstance，atotal geo thermal energy from three typical shale reservoirs has been estimated at 1.84×1013 GJ，with a recoverable portion of 9.22× 1011 GJ，equivalent to 3.15×1010 t of standard coal. In this study，diferent closed-loop heat extraction models were developed，includingasinglehorzontalwell（coaxialsystem）andadual-orizontalwellretrofittedintoacomplexstructuredsystemforextracting geothermal energyfromdepletedshalegasreservoirs，basedonthe Silurian LongmaxiFormationin the Jiaoshibaarea.Finite-elementsimulations wereperformedtoevaluatethewellperformanceandexaminetheefectsof wel configuration and operational parameters. The simulation results indicate that，under conditions of a 1500m3/d water circulation rate at 20∘C injection temperature，and with 1500m horizontal section and cement sheath thermal conductivity of 1.5 W/（m ·K），the coaxial system initially can obtain a wellhead outlet temperature of 60.63∘C and a heat extraction rate of （20 2948.91kW ，while that of the complex structured well can achieve 65.81°C and 3325.64kW ，respectively. After 10 years of operation，the wellhead temperature and heat extraction rate may decline to 40.00qC and 1451.40kW for the coaxial system，and to 49.14C and 2114.77kW for the complex structured well，demonstrating the superior performance of the latter wellconfiguration.Increasing the water circulationratecan enhance theheatoutput butlower theoutlettemperature，and higherinjectiontemperaturecanraiseoutlet temperaturebutreduceheat extractionrate.Longerhorizontalsectionlengthcan effectively improve the both production parameters.

Keywords： shale gas reservoirs；abandoned well；geothermal energy；closed lop circulation； heat mining potential

地热能作为储量丰富、分布广泛且稳定可靠的清洁可再生能源，其大规模高效开发对中国实现“双碳”目标意义重大[1-2]。（剩余14225字）