英语翻译While underground natural gas storage is safe and effect

英语翻译While underground natural gas storage is safe and effective,some projects have leaked,mostly caused by poorly completedor improperly plugged and abandoned wells and by leaky faults(Gurevich et al.,1993; Lippmann and Benson,2003; Perry,2005).Abandoned oil and gas fields are easier to assess asnatural gas storage sites than are saline formations,because thegeological structure and caprock are usually well characterizedfrom existing wells.At most natural gas storage sites,monitoringrequirements focus on ensuring that the injection well is notleaking (by the use of pressure measurements and through insitu downhole measurements of temperature,pressure,noise/sonic,casing conditions,etc.).Observation wells are sometimesused to verify that gas has not leaked into shallower strata.