页岩气的测井响应特征 翻译

1、2页岩气的测井响应特征2.1页岩气的常规测井响应页岩气的常规测井响应主要包括页岩储层的自然伽马、井径、声波时差、中子孔隙度、地层密度、岩性密度和深浅电阻率等。吴庆红等(2011)研究认为斯伦贝谢公司于2004年开展了页岩气测井解释，建立了页岩气测井系列，包括自然伽马、补偿中子、补偿密度、电阻率、声波扫描、电阻率成像(FMI)、伽马能谱(HNGS)和元素俘获能谱测井(ECS)等，其中声波扫描、电阻率成像、元素俘获能谱测井是页岩测井的关键技术10。潘仁芳(2009)研究总结了对页岩气储层有效的测井曲线及对应的响应关系11，见表3。表3页岩气测井曲线响应特征(文献11)Tab.3Responsech

2、aracteristicsofshalegaswelllogging(data11)测井曲线输出参数曲线特征影响因素自然伽马自然放射性高值(大于100API),局部低值泥质含量越高，自然伽马值越大；有机质中可能含有高放射性物质。井径井眼直径扩径泥质地层扩径；有机质的存在使井眼扩径更加严重。声波时差时差曲线较高，有周波跳跃岩性密度；泥岩页岩砂岩，有机质丰度高，声波时差大；含气量增大声波值变大；遇裂缝发生周波跳跃，井径扩大。中子孔隙度中子孔隙度高值束缚水使测量值偏高；含气量增大使测量值偏低；裂缝地区的中子孔隙度变大。地层密度地层密度中低值含气量大密度值低；有机质使测量值偏低；裂缝地层密度值偏低、井

3、径扩大。岩性密度有效光电吸收指数Pe低值烃类引起测量值偏小；气体引起测量值偏小；裂缝带局部曲线降低。深浅电阻率深探测电阻率浅探测电阻率总体低值，局部高值；深浅侧向曲线几乎重合地层渗透率；泥质和束缚水均使电阻率偏低；有机质干酪根电阻率极大，测量值局部为高值。2.2页岩气的常规测井系列裸眼井测井常用三大测井系列、十一条测井曲线，可解决储层的岩性划分、物性评价和含油气性评价等。由于页岩气测井的特殊性，需要对常规测井系列进行方法组合优选。笔者认为，页岩气测井的主要内容应包括：岩性定性识别和定量评价、含气层的划分与评价、储集空间和渗流空间物性评价。开展页岩气测井的关键问题是，那里是页岩层、源岩有机质含量

4、如何、页岩含气性如何、裂缝等储渗空间发育程度怎样。页岩气测井评价中，岩性定性识别和定量评价的常规测井方法主要包括自然电位测井、自然伽马测井和井径测井；含气层划分与评价的主要测井方法包括深浅侧向或深中感应电阻率测井、声波时差测井、密度测井和中子测井；储集空间和渗流空间物性评价的主要测井方法是声波时差测井、密度测井和中子测井。值得指出，页岩气常规测井系列从方法上似乎涵盖了现代测井全部方法，但页岩气测井方法组合和资料解释的侧重点却与石油测井有所不同。这与页岩气本身的特殊性密切相关。测井新技术中的核磁双Tw测井，进行差谱分析后，可根据差谱识别油、气、水层，对双TE测井进行移谱分析,可以判断气层。时间推

5、移测井,下套管后最佳时间测量的中子与固井后24h内测量的中子曲线重叠，利用其差值可以评价气层2。2LoggingResponseCharacteristicsofShaleGas2.1 ConventionalLoggingResponseofShaleGasConventionalloggingresponsesofshalegasmainlyincludenaturalgammaray,welldiameter,acoustictime,neutronporosity,formationdensity,lithologydensityanddepthresistivityofshalere

6、servoir.Onthebasisoftheresearchin2011,WuQinghong,etcthinkthatSchlumbergerCompanyhascarriedouttheloggingdatainterpretationofshalegasandhasestablishedloggingsuiteofshalegasin2004.Thisloggingsuiteincludesnaturalgammaray,compensationneutrons,compensationdensity,resistivity,soundwavesscanning,resistivity

7、imaging(FMI),gammarayspectrum(HNGS)andelementcapturedspectrometrylogging(ECS)andsoon.Andamongthese,thekeytechnologiesofshaleloggingaresoundwavesscanning,resistivityimagingandelementcapturedspectrometrylogging10.In2009,PanRenfanghassummarizedtheloggingcurvesthatareeffectivetoshalegasreservoirandtheir

8、correspondingrelationshipsasshowninTable3.2.2 ConventionalLoggingSuiteofScaleGasOpenholeloggingusuallyusesthreeloggingsuitesincludingelevenloggingcurvestosolvetheproblemoflithologydivision,physicalparametersevaluationandoilinessevaluationofthereservoir.Becauseoftheparticularityofshalegaslogging,conv

9、entionallogseriesneedtobechoosedandcombinedrenewedly.Intheauthor'sopinion,themaincontentofshalegasloggingshouldincludethequalitativeidentificationandquantitativeevaluationofthelithology,theclassificationandevaluationoftheaerationzoneandthephysicalparametersevaluationofthereservoirspaceandseepage

10、space.Theimportantproblemsofscalegasloggingarethesituationofshalestrata,organicmattercontentofsourcerock,gascontentofshaleandpermeabilityspaceabundanceofreservoir.Inshalegasloggingevaluation,theconventionalloggingmethodsofthequalitativeidentificationandquantitativeevaluationofthelithologymainlyinclu

11、denaturalpotentiallogging,naturalgammarayloggingandwelldiameterlogging;theconventionalloggingmethodsoftheclassificationandevaluationofaerationzonearemainlyincludedepthlateralloggingordepth-midinductionresistivitylogging,acoustictimelogging,densityloggingandneutronlog;theconventionalloggingmethodsofp

12、hysicalparametersevaluationofreservoirspaceandseepagespacemainlyincludeacoustictimelogging,densityloggingandneutronlog.It'isworthpointingoutthatshalegasconventionalloggingseriesseemstocoverallmodernloggingmethods,buttheemphasisofthecombinatorialmethodsanddatainterpretationofshalegasloggingisquit

13、edifferentfromoilwelllogging.Thisisrelatedwiththespecialdensityoftheshalegasitself.MRIdoubleTwloggingisoneloggingmethodofofnewloggingtechnology.Thestepsofthisloggingmethodareasfollow:First,thedifferentialspectrumshouldbeanalsized.Second,accordingtothedifferentialspectrum,oil,.wanterandgasshouldbedis

14、tinguished.Third,theshiftedspectrumanalysistothedoubleTEloggingshouldbedone.Then,theairlayercanbeidentified.TimelapseloggingisthatairlayerisevaluatedbytheD-valueofdataoftheneutronmeasuredatthebesttimeafterrunningcasingandtheneutronmeasuredwithin24hoursaftercementing2.Tab.3Responsecharacteristicsofsh

15、alegaswelllogging(data11)LoggingCurvesOutputParametersCurvesCharacteristicsInfluencingFactorsnaturalgammaraynaturalradioactivityhighvalue(>100API),partiallowvaluethehighershalecontent,thehighervalueofthenaturalgammaray;highradioactivematerialmaycontainedinorganicmatterwelldiameterholediameterhole

16、enlargementholeenlargementofshalyformation;moreseriousholeenlargementbecausetheexistenceoftheorganicmatteracoustictransittimetimeequationcurvehigh,cycle-skipsexistinglithologydensity:mudrock<shale<sandstone,thehigherabundanceoforganicmatter,thehighervalueofacoustictransittime;thecontentofgasan

17、dthevalueofacoustictransittimeincreasing;cycle-skipsandholeenlargementexistingwhenmeetingcracksneutronporosityneutronporosityhighvaluebondwatermakingthemeasuredvalueonthehighside;theincreasinggascontentmakingthemeasuredvalueonthelowside;theneutronporositybecominggreaterinthecrackareastratadensitystr

18、atadensitymidandlowvaluethehighergascontent,thelowerdensityvalue;theorganicmattermakingthemeasuredvalueonthelowside;crackmakingthestratumdensityonthelowsideandholeenlargementlithologydensityeffectivephotoelectricabsorptionindexPelowvaluethehydrocarbon)makingthemeasuredvalueonthelowside;thegasmakingt

19、hemeasuredvalueonthelowside;partialcurvesreducinginthecrackzonedepthandshallowresistivityDeepandshallowdetectingresistivityoveralllowvalue,partialhighvalue,deepandshallowlateralcurvesalmostcoincidencingpermeabilityofthestratum,saleandboundwaterallmakingthevalueofresistivityonthelowside;quitehighvalu

20、eofthekerogenresistivityandhighvalueappearingpartially3.3页岩气的测井评价技术展望3.3 TheOutlookofScaleGasWellLoggingEvaluationTechnology由于页岩气自身的特殊性，能够用于页岩气评价的测井资料往往受到多种因素控制，直接采用单一测井信息或某一储层参数进行页岩气评价解释研究，除了在一些特殊情况下可以取得满意效果外，一般很难推广使用。当前的最佳选择是基于地质、岩心、测井和生产动态资料开展四性关系研究，建立有关页岩气评价地质参数解释模型，以利用测井资料进行页岩气评价。由于页岩气储层参数与多种测井

21、信息之间的定量关系往往难以确定，因此，可借用现代数学中的灰色关联判别技术和神经网络技术进行页岩气的精细分析和预测评价，借用R/S变尺度分析技术开展页岩气层裂缝识别与评价。这些技术方法的优点是勿需考虑具体的数学模型，“隐含式”可表达出页岩气储层参数与测井响应之间的非线性关系，从而实现页岩气储层的定量分析22,23。另外，将新的测井技术(比如核磁共振测井、阵列感应测井等)以及精细二维及三维地质勘探解释技术8引入到页岩气综合评价中，多角度、多方位地收集页岩气储层的相关信息，从而提高页岩气层的测井综合评价精度。3.3 TheOutlookofScaleGasWellLoggingEvaluationT

22、echnologyFortheparticularityofshalegasitself,loggingdatathatcanbeusedtoevaluateshalegasiscontrolledbyvariousfactors.Exceptgettingsomesatisfiedresultsthespecialcircumstances,directusingsingleloggingdataoracertainreservoirparameterstoevaluate,interpretshalegasisgenerallydifficulttowidelyuse.Atpresent,

23、thebestoptionisbasedongeology,core,wellloggingandproductiondynamicdata,carryingoutthestudyof“therelationofthefourcharacters”,buildingshalegasevaluationmodel,andtheusingloggingdatatoevaluateshalegas.Becauseitisalwaysdifficulttomakesurethequantificationalrelationshipbetweenshalegasreservoirparametersa

24、ndvariousloggingdata,shalegascanbesubtlyanalyzedandevaluatedbygreycorrelationdiscriminanttechnologyandneuralnetworktechnologyincontemporarymathematics,andshalegasstratumcrackandshalegasstratumcrackcanbeidentifiedandevaluatedbyR/Sanalysistechnologyofvariablescale.Theadvantagesofthesetechniquesarethat

25、specificmathematicalmodelisnotrequiredtoconsidered,andthenonlinearrelationshipbetweenshalegasreservoirparametersandtheresponseofwelllogging.Thequantificationalanalysisofshalegasreservoircanberealized22,23.Inaddition,introducingnewloggingtechnology(suchasnuclearmagneticresonancelogging,arrayinduction

26、logging,etc),subtle2Dand3Dgeologicalexplorationinterpretationtechnologyintoshalegascomprehensiveevaluation,aswellascollectingthecorrelativedataofshalegasreservoirfrommulti-angles,thereby,canimprovethecomprehensiveevaluationprecisionofshalegaswelllogging.3.2页岩本身具有很低的渗透率，但网状裂缝系统大大提高了页岩的储气能力，因此，在对页岩气藏进

27、行储量计算时，对页岩中裂缝系统的评价十分重要。目前，常用测井方法评价裂缝，如微电阻率测井、声波测井、双侧向测井、成像测井等20，21。声波测井对低角度和水平裂缝反映较好、对高角度裂缝反映较差。双侧向测井是近年发展起来的识别裂缝的好方法，裂缝越发育，双侧向电阻率越低；垂直及网状裂缝越发育双侧向差异越大。高角度裂缝的有效性表现为电阻率曲线在高阻背景上有所下降，深浅侧向电阻率幅度差很大，但是如果差异过大，裂缝的张开度虽很大，但横向延伸很短，裂缝的有效性就很差；低角度裂缝的有效性表现在电阻率曲线在高阻背景上的明显降低，曲线形状尖锐，一般呈负差异，说明横向延伸较远，幅度差越大，张开角度就越大，有效性就越

28、好；如果出现正差异，说明横向延伸短，有效性就差。此外，应用于页岩裂缝识别的还有井径曲线的变化、异常流体压力和应力的关系、相干分析技术等16。Shaleitselfpossessesverylowpermeability.However,thesystemofnetworkfracturesgreatlyimprovesthegasstoringcapacityofshale.Therefore,whenthereservesofshalegasreservoirarecalculated,theevaluationofshalecracksystemisveryimportant.Atpres

29、ent,frequently-usedwellloggingmethodsaremicroresistivitylogging,acousticlogging,duallaterolog,imaginglagging,andsoon.Acousticloggingcanreflectlow-angleandhorizontalcrackwell,andcannotreflecthigh-anglecrackwell.Duallaterolog,whichdevelopsinrecentlyyears,isthebestwaytoidentifycrack,themoredevelopmentalcrack,thelowerduallateralelectricresistancerat