氣藏工程翻譯版課件Chapter4.1 Decline-Curve Analysis for Gas Wells

氣藏工程翻譯版課件Chapter4.1Decline-CurveAnalysisforGasWellsTomasterthechanginglawofproductioncanhelpustodesignthereasonableproductionplan,takemeasuresintimetomakeupfortheproductiondecline.了解產(chǎn)量的變化規(guī)律，有助于我們制定合理的生產(chǎn)計(jì)劃，及時(shí)采取措施，彌補(bǔ)產(chǎn)量的遞減。4.1Introduction41、Conventional(Arps)productiondeclinelawandapplications常規(guī)（ARPS）產(chǎn)量遞減規(guī)律及其應(yīng)用Lifetimeofoilfield-DivisionAccordingtoproduction產(chǎn)量上升階段產(chǎn)量穩(wěn)定階段產(chǎn)量遞減階段Declinetypeisdependedbygeometry,fluidpropertyanddevelopmentmodeofthereservoir.遞減類型取決于幾何結(jié)構(gòu)、流體性質(zhì)及儲層的開發(fā)模式4.1Introduction5一般說來，油氣田越大，全面建成生產(chǎn)能力時(shí)間越長，穩(wěn)產(chǎn)速度要求越高，則產(chǎn)量上升階段越長。氣藏類型地質(zhì)條件開發(fā)政策開發(fā)措施工藝技術(shù)水平氣田開發(fā)階段的時(shí)間、長短產(chǎn)量水平及其變化規(guī)律

天然能量充足或保持壓力水平開采，穩(wěn)產(chǎn)速度較低，則穩(wěn)產(chǎn)階段越長；能量不充足，穩(wěn)產(chǎn)速度高，則產(chǎn)量穩(wěn)產(chǎn)期短。穩(wěn)產(chǎn)期的采氣速度越高，產(chǎn)量遞減會越快；封閉型彈性驅(qū)動油氣藏的產(chǎn)量遞減快。

關(guān)鍵是了解產(chǎn)量遞減期間的變化規(guī)律。6Thebasis基本原則:Assuming假設(shè):Matchpastproductionperformancehistoriesortrends過去的生產(chǎn)性能歷史或趨勢相匹配Futureproductioncontinuestofollowthepasttrend未來的生產(chǎn)繼續(xù)遵循過去的趨勢Byanalyzingthelong-termgas-productiondata通過分析長期天然氣生產(chǎn)數(shù)據(jù)Individual

well單井Entire

field

整個(gè)區(qū)域From7Application應(yīng)用:Estimateoriginalgasinplace估計(jì)儲量Predictultimategasrecovery預(yù)測氣藏最終采收率Determinetheremainingproductivelife確定剩余的生產(chǎn)能力Estimatetheindividualwellflowingcharacteristics估計(jì)單井流動特性Estimatingultimategasrecoveries最終的氣體回收率估計(jì)Predictwellorfieldperformance預(yù)測單井和整個(gè)區(qū)域的性能8Oilandgaswellsusuallyreachtheirmaximumoutputshortlyaftercompletion.Fromthattime,theydeclineinproduction,therapidityofdeclinedependingontheoutputofthewellsandonotherfactorsgoverningtheirproductivity,whichistermedasDeclineRate(遞減率).石油和天然氣的井通常達(dá)到最大產(chǎn)量不久。從那時(shí)起，他們產(chǎn)量下降，下降取決于井的輸出和其他因素，他們的生產(chǎn)力的下降，這被稱為遞減率DeclineRateRateofproductionchangeperunittime.howmuchofproductionhasdecreasedcomparedwithitsoriginalquantityduringunittime.單位時(shí)間產(chǎn)量變化率。在單位時(shí)間與原來相比產(chǎn)量減少了多少。4.3ConventionalAnalysisTechniques9DeclineRate:Rateofproductionchangeperunittime單位時(shí)間產(chǎn)量變化率D—instantaneousdeclinerate，1/d

or1/mon；D0—initialdeclinerate，1/d

or1/mon；t—time，d

ormon；k—coefficient(比例系數(shù))；Q—productionatt，m3/d

orm3/mon；Q0—initialproduction，m3/d

orm3/mon；n—Arpsdecline-curveexponent(遞減指數(shù));

dQ/dt–productionchangingduringtheunittime.4.3ConventionalAnalysisTechniquesArpsmodel10Di:Initialdeclinerate初始遞減率(1)ThewellisproducedatconstantBHP.這口井在恒定井底流壓生產(chǎn)(2)Thewellisproducingfromanunchangingdrainageareawithno-flowboundaries.以及在無邊界大地層生產(chǎn)(3)Thewellhasconstantpermeabilityandskinfactor.井具有恒定的滲透率和表皮因子(4)Itmustbeappliedonlytoboundary-dominatedflowdata它必須僅適用于邊界控制流.4.3ConventionalAnalysisTechniquesArpsequationAssumptions假定:11DeclinerateslowdownGraphicalmethodtogetD:4.3ConventionalAnalysisTechniques0<n<1Hyperbolicdeclinen=1Harmonicdeclinen=0Exponentialdecline

12Expressedin表達(dá):(1)Gasproductionratevs.time產(chǎn)氣率與時(shí)間(2)Gasproductionratevs.cumulativegasproduction產(chǎn)氣率與累積產(chǎn)氣量Exponentialdecline-curve指數(shù)遞減曲線Harmonicdecline-curve調(diào)和遞減曲線Hyperbolicdecline-curve雙曲遞減曲線ThreetypesofArpsequation三種類型的Arps方程:1314semi-logplot半對數(shù)圖(1)Exponentialdecline指數(shù)遞減4.3ConventionalAnalysisTechniques15(1)Exponentialdeclineslope4.3ConventionalAnalysisTechniquesintercept截距slope斜率16(1)ExponentialdeclineCumulativeproductionindeclinestage累計(jì)產(chǎn)量下降階段:4.3ConventionalAnalysisTechniques17(1)ExponentialdeclineDofExponentialdeclineisconstant,

soitdeclinesquicklyandissuitableforclosed-elasticproductionandinitialstageofproductiondecline(D指數(shù)的下降是恒定的,因此迅速下降適用于封閉彈性開采以及產(chǎn)量遞減的初期)Slope4.3ConventionalAnalysisTechniques18(1)Exponentialdecline4.3ConventionalAnalysisTechniques19Time/yearGasProd.（108m3/year）Cumulativegasprod.（108m3）Cumulativegasprod.Indeclinestage（108m3）196461.1319.70.0196551.0370.751.0196642.3413.093.3196735.0448.0128.3196828.3476.3156.3(1)Exponentialdecline——exampleProductionhistoryofagasreservoirisasfollowing,tocalculateproductiondeclinetypeandtherelationalexpressionbetweenproductionandtime.氣藏的生產(chǎn)歷史如下，計(jì)算產(chǎn)量遞減類型、產(chǎn)量和時(shí)間之間的關(guān)系式4.3ConventionalAnalysisTechniques20(1)Exponentialdecline——example4.3ConventionalAnalysisTechniques21Maximumcumulativegasproduction最大累積產(chǎn)氣量：4.3ConventionalAnalysisTechniquesTime/yearGasProd.（108m3/year）Cumulativegasprod.（108m3）Cumulativegasprod.Indeclinestage（108m3）196461.1319.70.0196551.0370.751.0196642.3413.093.3196735.0448.0128.3196828.3476.3156.322(2)Harmonicdeclinen＝14.3ConventionalAnalysisTechniques23(2)Harmonicdecline4.3ConventionalAnalysisTechniquesCumulativeproductionindeclinestage累計(jì)產(chǎn)量下降階段:24(2)HarmonicdeclineTakeQt=1asminimumproductionrateindeclinestage以Qt=1為最低產(chǎn)量下降階段遞減的速度比較小，適合于晚期4.3ConventionalAnalysisTechniques25(3)Hyperbolicdecline4.3ConventionalAnalysisTechniques26(3)Hyperbolicdecline

遞減的指數(shù)可以發(fā)生變化，適用的范圍比較廣4.3ConventionalAnalysisTechniques27

不同的遞減類型主要取決于初始遞減率和遞減指數(shù)，其中主要的是遞減指數(shù)，遞減指數(shù)越大，遞減的速度越慢；初始遞減率越大，產(chǎn)量的遞減速度越快。影響參數(shù)：初始遞減率和遞減指數(shù)變化規(guī)律？4.3ConventionalAnalysisTechniques28Judgmentofdeclinetype遞減類型的判斷

在不同的開發(fā)階段，產(chǎn)量遞減的規(guī)律不同。在遞減階段初期，遞減比較快，常符合Exponentialdecline類型；在遞減的中期，一般符合Hyperbolicdecline類型；遞減階段的后期，一般符合Harmonicdecline類型。4.3ConventionalAnalysisTechniques29對于實(shí)際的產(chǎn)量變化數(shù)據(jù)，如何判定是屬于哪種遞減類型。影響遞減指數(shù)的因素很多，不同的驅(qū)動類型、地質(zhì)條件，n值不相同。圖解法典型曲線擬合法試湊法曲線位移法判別曲線法4.3ConventionalAnalysisTechniques30一、圖解法

圖解法就是根據(jù)實(shí)際生產(chǎn)數(shù)據(jù)，以表4-11中所列的基本關(guān)系式為理論基礎(chǔ)，研究某兩個(gè)變量之間的線性關(guān)系，從而判斷其遞減類型。

（1）指數(shù)遞減滿足下列條件之一，則可判斷為指數(shù)遞減：①實(shí)際資料在坐標(biāo)中成較好的線性關(guān)系。②實(shí)際資料在坐標(biāo)中成較好的線性關(guān)系。

4.3ConventionalAnalysisTechniques31

既不屬于指數(shù)遞減，也不屬于調(diào)和遞減的，應(yīng)屬于雙曲遞減。如果實(shí)際資料在坐標(biāo)中成較的線性關(guān)系，則屬于調(diào)和遞減。

一、圖解法（3）Hyperbolicdecline（2）Harmonicdecline4.3ConventionalAnalysisTechniques32圖解法典型曲線擬合法試湊法曲線位移法4.3ConventionalAnalysisTechniques33各種遞減類型都可以寫成如下的形式：二、典型曲線擬合法4.3ConventionalAnalysisTechniques34圖解法典型曲線擬合法試湊法曲線位移法4.3ConventionalAnalysisTechniques35

取不同的值，求出，將此數(shù)據(jù)與相應(yīng)的值在直角坐標(biāo)系上作圖。當(dāng)取值適當(dāng)時(shí)，為一直線，根據(jù)直線的斜率可求出初始遞減率；如果取值偏大，則成一條向上彎曲的曲線；如果取值偏小，則成一條向下彎曲的曲線。三、試湊（法）法4.3ConventionalAnalysisTechniques36三、試湊（法）法4.3ConventionalAnalysisTechniques37圖解法典型曲線擬合法試湊法曲線位移法4.3ConventionalAnalysisTechniques38

所謂曲線位移法，就是將畫在雙對數(shù)坐標(biāo)系上成曲線的產(chǎn)量和時(shí)間的關(guān)系曲線，向右