简介：TheresistivityexperimentalmeasurementsofcoresamplesdrilledfromlowpermeabilityreservoirsofOrdosBasin,NorthwestChina,illustratethatthecementationfactorsarenotagminate,butvaryfrom1.335to1.749.Thisleadstoachallengefortheestimationofwaterandhydrocarbonsaturation.BasedontheanalysisofPurcellequationandassumptionthatrockresistivityisdeterminedbytheparallelconnectionofnumerouscapillaryresistances,atheoreticalexpressionofcementationfactorintermsofporosityandpermeabilityisestablished.Then,cementationfactorcanbecalculatediftheparametersofporosityandpermeabilityaredetermined.Inthefieldapplication,porositycanbeeasilyobtainedbyconventionallogs.However,itisatoughchallengetoestimatepermeabilityduetothestrongheterogeneityoflowpermeabilityreservoirs.Thus,theSchlumbergerDollResearch(SDR)modelderivedfromNMRlogshasbeenproposedtoestimatepermeability.BasedontheanalysisofthetheoreticalexpressionsofcementationfactorandSDRmodel,anovelcementationfactorpredictionmodel,whichisrelevanttoporosityandlogarithmicmeanofNMRT2spectrum(T2lm),isderived.TheadvantageofthismodelisthatalltheinputinformationcanbeacquiredfromNMRlogsaccurately.Inordertoconfirmthecredibilityofthenovelmodel,theresistivityandcorrespondinglaboratoryNMRmeasurementsof27coresamplesareconducted.Thecredibilityofthemodelisconfirmedbycomparingthepredictedcementationfactorswiththecoreanalyzedresults.Theabsoluteerrorsforallcoresamplesarelowerthan0.071.Oncethismodelisextendedtofieldapplication,theaccuracyofwaterandhydrocarbonsaturationestimationwillbesignificantlyimproved.

简介：本报讯近日，地震预警四川省重点实验室传出消息，首都圈地震预警系统经过近一年半的建设，目前已建成并投入运行，将为首都圈民众和地铁、化工等重大工程提供地震预警服务。