### Transcription of Oil and Gas Pipeline Design, Maintenance and Repair

1 PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairDr. Abdel-Alim HashemProfessor of Petroleum Engineering Mining, Petroleum & Metallurgical Eng. Dept. Faculty of Engineering Cairo University 2: Steady-State Flow of Gas through PipesOil and Gas **Pipeline** **design** , **Maintenance** and **Repair** PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairINTRODUCTION Pipes provide an economic means of producing and transporting fluids in large volumes over great distances The flow of gases through piping systems involves flow in horizontal, inclined, and vertical orientations, and through constrictions such as chokes for flow control PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairENERGY OF FLOW OF A FLUID PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairBERNOULLI'S EQUATION P = the pressure V = the velocity Z = the height Hp= the equivalent head added to the fluid by a compressor at A hf= represents the total frictional pressure loss between points A and B.

2 2222 AABBApBfPVPVZHZhgg +++ =+++ PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairVELOCITY OF GAS IN A **Pipeline** =VQA1112 22=qqMM ==111VV =111 VqA=111 22 bqq qbM ===11bbqq = 1111P=Z RT 1111 PZRT =bbPZRTbb =b111b1bPTZTPZbqq = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairVELOCITY OF GAS IN A **Pipeline** V1 = upstream gas velocity, ft/s qb= gas flow rate, measured at standard conditions, ft3/day (SCFD) d= pipe inside diameter, in. Pb= base pressure, psia Tb= base temperature, R (460 + F) P1= upstream pressure, psia T1= upstream gas temperature, R(460 + F) b111bb1 PTsince == 1b1b1112b1b1ZP4 144 ZPTTTPTP bbqxqVAd == ()TPbqVUSCSd = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairVELOCITY OF GAS IN A **Pipeline** Gas velocity at section 2 is given by Gas velocity at any point in a **Pipeline** is given = ()TPbqVUSCSd = ()TPbqVSId = PE 607.

3 Oil & Gas **Pipeline** **design** , **Maintenance** & RepairEROSIONAL VELOCITY Vmax= maximum or erosional velocity, ft/s = gas density at flowing temperature, lb/ft3 Z = compressibility factor of gas, dimensionless R = gas constant = ft3psia/lb-moleR T = gas temperature, oR g= gas gravity (air = ) P = gas pressure, psiamax100V =max10029gZRTVP = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairExample 1 A gas **Pipeline** , NPS 20 with in. wall thickness, transports natural gas (specific gravity = ) at a flow rate of 250 MMSCFD at an inlet temperature of 60 F. Assuming isothermal flow, calculate the velocity of gas at the inlet and outlet of the pipe if the inlet pressure is 1000 psig and the outlet pressure is 850 psig. The base pressure and base temperature are psia and 60 F, respectively.

4 Assume compressibility factor Z = What is the erosional velocity for this **Pipeline** based on the above data and a compressibility factor Z = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairSolution For compressibility factor Z = , the velocity of gas at the inlet pressure of 1000 psig is Gas velocity at the outlet is The erosional velocity is found for Z = , 512250 + + == == ft/s29 PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairREYNOLD S NUMBER OF FLOW Re= Reynolds number, dimensionless V= average velocity of gas in pipe, ft/s d = inside diameter of pipe, ft = gas density, lb/ft3 = gas viscosity, lb/ft-s()eVdRUSCS = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairREYNOLD S NUMBER OF FLOW USCS or SI Re= Reynolds number, dimensionless V= average velocity of gas in pipe, ft/s or m/s d = inside diameter of pipe, ft or m = gas density, lb/ft3or kg/m3 = gas viscosity, ()eVdRUSCS = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairREYNOLD S NUMBER OF FLOW IN CUSTOMARY UNITS Pb= base pressure, psia Tb= base temperature, R (460 + F) g= specific gravity of gas (air = ) q = gas flow rate, standard ft3/day (SCFD) d = pipe inside diameter, in.

5 = gas viscosity, ()gbebqPRUSCSTd = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairREYNOLD S NUMBER OF FLOW IN CUSTOMARY UNITS Pb= base pressure, kPa Tb= base temperature, K (273 + C) g= specific gravity of gas (air = ) q = gas flow rate, standard m3/day (SCFD) d = pipe inside diameter, mm = gas viscosity, ()gbebqPRSITd = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairFlow Regime Re 2000 Laminar flow, 2000 > Re 4000 Critical flow Re > 4000 Turbulent flow PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairExample A natural gas **Pipeline** , NPS 20 with in. wall thickness, transports 100 MMSCFD. The specific gravity of gas is and viscosity is Calculate the value of the Reynolds number of flow.

6 Assume the base temperature and base pressure are 60 F and psia, respectively. PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairSolution Pipe inside diameter = 20 - 2 x = in. The base temperature = 60 + 460 = 520 R Using Equation we get Since Re is greater than 4000, the flow is in the turbulent 100 , 331, 19exxRx == PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairFRICTION FACTOR ff= Fanning friction factor fd= Darcy friction factor For laminar flow4dfff=64efR= PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairFRICTION FACTOR FOR TURBULENT FLOW PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairINTERNAL ROUGHNESSType of pipe e, in e,mm Drawn tubing (brass, lead, glass) Aluminum pipe Plastic-lined or sand blasted Commercial steel or wrought iron Asphalted cast iron Galvanized iron Cast iron Cement-lined Riveted steel PVC, drawn tubing, glass Concrete Wrought iron Commonly used well tubing and line pipe.

7 New pipe 12-months old 24-months old PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairTRANSMISSION FACTOR The transmission factor F is related to the friction factor fas follows 2Ff=24fF= PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairRelative Roughness e = absolute or internal roughness of pipe, in. d = pipe inside diameter, roughness = ed PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairFLOW EQUATIONS FOR HIGH PRESSURE SYSTEM General Flow equation Colebrook-White equation Modified Colebrook-White equation AGA equation Weymouth equation Panhandle A equation Panhandle B equation IGT equation Spitzglass equation Mueller equation Fritzsche equation PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairGENERAL FLOW EQUATION (USCS) qsc= gas flow rate, measured at standard conditions, ft3/day (SCFD) f = friction factor, dimensionless Pb= base pressure, psia Tb = base temperature, R( 460 + F) P1= upstream pressure, psia P2= downstream pressure, psia g= gas gravity (air = ) Tav= average gas flowing temperature, R (460 + F) L = pipe segment length, mi Zav= gas compressibility factor at the flowing temperature, dimensionless d = pipe inside diameter, in.

8 () ()bscbgavavPPdTqUSCSPZTfL = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairSteady flow in a gas **Pipeline** PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairGENERAL FLOW EQUATION (SI) qsc= gas flow rate, measured at standard conditions, m3/day f= friction factor, dimensionless Pb= base pressure, kPa Tb= base temperature, K (273 + C) P1 = upstream pressure, kPa P2 = downstream pressure, kPa g= gas gravity (air = ) Tav= average gas flowing temperature, K (273 + C) L= pipe segment length, km Zav= gas compressibility factor at the flowing temperature, dimensionless d = pipe inside diameter, mm() 10()bscbgavavPPdTqxSIPZTfL = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairGeneral flow equation in terms of the transmission factor F F = transmission factor() ()bscbgavavPPdTqFUSCSPZTL = 2Ff=() 10()bscbgavavPPdTqxFSIPZTL = PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairEFFECT OF PIPE ELEVATIONS s = elevation adjustment parameter, dimensionless Z= elevation difference e = base of natural logarithms (e = ) () ()sbscbgavavePePdTqFUSCSPZTL = () 10()sbscbgavavePePdTqxFSIPZTL = se(e - 1)L = Lsgavavs = ( ) ( z)/(Z T ) (USCS) gavavs = ( ) ( z)/(Z T ) (SI) PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairGas flow through different elevations13112 12123123(1)(1)(1)(1).

9 0nnsssss sssenineee eeeeLL LLLsssss + =++ ++ s(e - 1)j = s311112 23 jLejLe s =+ + ++ PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairAVERAGE PRESSURE IN PIPE SEGMENT Or1212122= 3avPPPPPPP ++ + 331222122=3avPPPPP PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairCOLEBROOK-WHITE EQUATION A relationship between the friction factor and the Reynolds number, pipe roughness, and inside diameter of pipe. Generally 3 to 4 iterations are sufficient to converge on a reasonably good value of the friction factor f= friction factor, dimensionless d = pipe inside diameter, in. e = absolute pipe roughness, in. Re= Reynolds number of flow, dimensionless() logTurbulent = + PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairCOLEBROOK-WHITE logTurbulent flow in smooth pipeefRf = ()12 logturbulent flow in fully rough pipes PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairExample A natural gas **Pipeline** , NPS 20 with in.

10 Wall thickness, transports 200 MMSCFD. The specific gravity of gas is and viscosity is lb/ft-s. Calculate the friction factor using the Colebrook equation. Assume absolute pipe roughness = 600 in. PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairSolution Pipe inside diameter = 20 - 2 x = in. Absolute pipe roughness = 600 ~ in. = in. First, we calculate the Reynolds number Re = ( (60+460))x(( x 200 x 106) /( 19)) = 10,663,452 This equation will be solved by successive iteration. Assume f= initially; substituting above, we get a better approximation as f= Repeating the iteration, we get the final value as f= Therefore, the friction factor is PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairMODIFIED COLEBROOK-WHITE EQUATION() logturbulent flow = + () logwith transmission = + PE 607: Oil & Gas **Pipeline** **design** , **Maintenance** & RepairAMERICAN GAS ASSOCIATION (AGA) EQUATION Dfknown as the pipe drag factor depend on bend index, Its value ranges from to Ft= Von Karman smooth pipe transmission factor logVon Karman, for rough pipedFe = 4logVon Karman, smooth = = PE 607.