Dynamic simulation research on injection and withdrawal performance of underground salt cavern natur Dynamic simulation research on injection and withdrawal performance of underground salt cavern natur

Dynamic simulation research on injection and withdrawal performance of underground salt cavern natur

  • 期刊名字:哈尔滨工业大学学报(英文版)
  • 文件大小:403kb
  • 论文作者:CAO Lin,TAN Yu-fei
  • 作者单位:School of Municipal and Environmental Engineering
  • 更新时间:2020-09-15
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论文简介

Joumal of Harbin Institue of Technology (New Series),Vol. 16, No. 5, 2009Dynamic simulation research on injection and withdrawal performanceof underground salt cavern natural gas storageCAO lin, TAN Yu-fei曹琳, 谭羽非(School of Municipel and Environmental Engineering, Harbin Institute of Technology, Habin 150090, China, caolin1212@ 126. com)Abstract: 0wing to perfet impemeability , dynamics stability , flexible and eficient operation mode and strongadjustment,underground salt cavem natural gas storage is especially adapted to be used for short-term dispatch.Bused on characteristics of gas flow and heat transfer, dynamic mathematice models were built to simulate the in-jection and withdrawal performance of underground salt cavem gas storage. Temperature and pressure variationsof natural gas in gas slorage were simulated on the basis of building models during withdrawal operation, andfactors aeting on the operation of gas storage were also analyzed. Therelore, these models can provide theore-tic foundation and technology support for the design, building and operation of salt cavern gas storage.Key words: salt cavem gas storage; mathematic models; dynamic simulationCLC number: TE82Document code: AArticle ID: 1005-9113(2009 )05-0633-05Owing to perfect impermeability, dynamics stabili-is assumed to be a volume equivalent cylinder in shape.tyl1] , flexible operation mode and capable of quick dis-Natural convection of gas in the cavem is neglected.patch, underground salt cavern natural gas storage is And only vertical flow of natural gas is considered.especially adapted to be used for short-term dis-1. 1 Establish of Mathematics Models in Salt Cav-patchhl2,So far, there are lots of underground salerncaverm natural gas storages in America, Europe and1. 1.1 Mass balance equation in cavernRussia, and they play an important role in gas dis-The relationship between temperature and pressurepatch. However, there is only one underground salof natural gas in the cavern follows the real gas law.cavem natural gas storage-“Jintan” salt cavem natu-The mass balance in a natural gas storage cavemn is de-ral gas storage in our country.scribed by:During design and building of salt caverm gas stor-_P。(t)VM=mws+f.(sgn(q.)mw +m.,)du .age, on the one hand, natural gas in cavemn exchangeszm(t)RT_(t)heat with salt formation by natural convection; On the(1)other hand,continuous injecting and withdrawal opera-wherePq, Tq, Mg, zm are pressure , temperature, mo-tion make temperature and pressure of natural gas inlecular weight and compressibility factor of natural gascavem change. Based on characteristics of gas flow andin cavern respectively. mqp, mpi are molar count of nat-heat transfer, dynamic mathematic models are buit toural gas in cavem at initial time, and in injection orsimulate thermodynamic performance of undergroundwithdrawal operation respectively. m.f is the molarsalt cavern gas storage in circle running. Then, thecount of gas leakage. t。 - to is operation time. Then,temperature and pressure variations of gas storage insgn(u;) is a sign. For withdrawal operation, sgn(q.)operation are simulated on basis of buit models. The=- 1; In injection operation, sgn(qm) = 1.influence on operation of gas storage is analyzed.1. 1. 2 Energy balance equation in cavernTherefore, these models can provide theoretic founda-To calculate temperature of natural gas in cavem,tion and technology support for design, constructionthe following equation represents the time rate ofand operation of salt caverm gas storage. Research re-change of the caverm temperature. And it is used tosults will be of realistic significance.describe the energy balance in cavern :1 Establish of Mathematics Models of Salt CaverndTg.[ VTs中mGas Storagem(5)+mag(G -T)+h.gn].For the purpose of simplifying models, the cavem中国煤化工(2)Reccived 2007 -12 -29..CHCNMHGSponsored by the National Natural Science Foundation of China ( Grant No. 50676025) and National Great Project of Scientife and Technical SupportingPrograme Funded by Ministry of Science & Technology of China During the 11th Five-year Plan ( Graund No.2006BAB03B09).●633●Journal of Harbin Instiue of Technology (New Series), Vol. 16,No.5, 2009where P∞isdensity of natural gas, Cmq is constant-vol-1.3Heat Transfer and Exchange Modelsume specific heat of natural gas, c, is constant-pressureThe heat transfer and exchange is described byspecific heat of inlet natural gas, T is temperature of] Fourier heat conduction equation:inlet natural gas, Am is surface area of cavemn, and 9wmaTm=a[87m+1 2(,27]。(6)is heat flux at the wall of caverm.Tr(1.2 Establish of Mathematics Models in Wellborewhere T is temperature of salt formation, T is time, a1.2. I Mass balance equation in wellboreis thermal diffusivity of salt, r is radial position in cyl-The natural gas flow is considered as an unstableinder coordinate system.flow in wellbore. And the mass balance in the wellboreInitial conditions: Te= const.is described by:I t=apm + a(Pu)=0.(3)Boundary conditions:8ay= constwhere Pxi is density of natural gas, Up is velocity of nat-ural gas, and y is vertical direction.aT.=am(Tm -Tn)I. 2.2 Momentum balance equation in wellboreNatural gas flow in wellbore performs following hy-In above Eq. (6), λ is thermal conductivity ofdrodynamics momentum equation :salt formation, axsm is convective heat transfer cofi-a(Pw") + a(ρ啦)。_ aPp-Pw8-cient of natural gas, Tmq is temperature at wall of cav-atdyem, Tqo is initial temperature of natural gas in cavem.sgn(yn)2d;(4)2 Numerical Solution Scheme of Modelswhere P: is pressure of natural gas, g is gravity acceler-ation ,fr is friction factor of natural gas , dn is waterpow-2.1 Numerical Solution of Cavern Modelser diameter of wellbore and sgn(uy) is a sign. ForEq.(I) can be rewrited by :p+& V+Awithdrawal operation, sgn(u;) = - 1; In injection op-出广(_9. +my)dx.eration, sgn(un) = 1.1. 2.3 Energy balance equation in wellbore(7)During gas operations, the fllowing equation is usedIn Eq. (2),differential cofficient of pressure toto describe the intemal energy balance within the wellbore:temperature is described by:(0TpaT( aP,望apiz+ r照PavCn(|)= 1'aT\aa+T=川后一路)(8)fpPw啦A:"9咖- sgn(0,)(5)Afer combined function (8) and (2) with real gas statuswhere Ap is heat exchange area between wellbore andequation", Eq.(2) can be got by difference methods.salt formation, and 9* is heat flux in wellbore.V_T_M,1 p+sz +Tmi-z(P,T.)T-T。+9IwPmCim(T-T) +AtpomAlRo\zxnTt+s~ znTF,T)P-P。Anal(T*W -T") .(9)In Eq. (9), calculation of gas density and specif-referred to Ref. [5].ic heat can be referred to Ref. [4], and the calcula-After combined Eqs. (7) and (9), Eq. (10) cantion of gas convective heat transfer coefficient can bebe described by :Fr(P*,TH*) =ho -M(Opu9m +m.) =0,z*T znT M「z +T-z(P,F) 1Fm(P ,T*)=V*Pmc当r1 -VpeCmTs.-Ah(m -T)-中国煤化工T-T=0A-z(P,T")HCNMHGP-P。)(10●634●Joumal of Harbin Instiue of Technology (New Series), Vol. 16, No. 5, 2009Combined the mass balance equation with energyEror precision:△P≤0.1 MPa,△Tm≤0.1 C.balance equation, the whole equation group is solved2. 2 Numerical Solution of Wellbore Modelsby Newton-Raphson iterative method with the iterativeTo apply the mass, momentum, and energy bal-precision of pressure and temperature less thanance equations to the wellbore during gas operation,0.1 MPa and 0. 1 K respectively. Newton-Raphson it-the wellbore is divided into many segments by node 8-erative is described by:nalysis method in the direction of depth. Each segmentperforms function (3), function (4) and functionraFgaFte(5). Eq. (12) can be got by dispersing function (3).07") =-Fim(P",T%),aPP%。= P% + A[(P的)' - (P2n)~"] +aFrsP# + aFest+: =Fm(,T), (11)[p°w(o)*_ - p°u(站)°] + sgn(可)"gSy-Axyfe*(动)(12)2dpEq. (13) can be got by dispersing function (4). .A[F(P;“,T") + Uog~"(Tπw -1;:*)+(wiom -会P*)T Ar:°pg°Th =2APE +pimhn2OPa +Pimt。(13)|q+7;心生-x(P-,T.)1T--T。F(P-",:*) =.在-(P.T*)p5*AyP--P2During solving function group (13),each seg-(17)ment models are calculated in tum in the direction of(1 + Bu)w“=出+T.depth. The physical properties of natural gas are 88-.4 Simultaneous Solution Stepsumed to be constant in each segment and are calculat-The primary variables that characterize the behav-ed using the average of the inlet and outlet tempera-ior of a salt cavern gas storage are caverm pressure Ptures and pressures.cavermn temperature Tr,bottom wellbore pressure F2.3 Numerical Solution of Salt Formation Heatbottom wellbore temperature T, wellhead pressure P,Transfer ModelsAfter Salt formation has been divided into severalwellhead temperature T, injection/ withdrawal rate C。units, Eq. (6) is scattered by shelter limited differenceand caverm pressure drop APm.During an injection operation, T, G, or SP andmethod.(1) Node temperature of cavem wall is describedPiqmx ( max permission operation pressure) are given inrandom initial Po and Tpo condition. Pmq < Pqmas, Tqby:≠TgandP = P。are in this process. Fistly, wellborer,=(1+---)*-.y.models are calculated in turm from the top to the bot-a(rz -ra(r-rom. After calculation, cavem models are solved.In Eq. (14), r and r2 are caverm wall radius and the(14)Then, P, T, Tq andPm or G, can be got by solvingEqs. (10), (12) and (13) simultaneously.first node radius of salt formation respectively.During a withdrawal operation, G, or SP and2) No. m (2≤m≤M) node temperature ofPmin ( min permission operation pressure) are given insalt formation is desecribed by:random initial Pr and To condition. P, > Pmin, T_ =(+B--+B=)r:x =TA +-→T4 +Tp and P_ = P。are in this process. Firstly, cavemVummodels are calculated. Then, new temperature andT,2≤m

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