Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Chapter 3Production from Two-Phase ReservoirsPETE 662Production EngineeringSingle Phase or Two-Phase FlowProperties of Saturated OilOil Formation Volume Factor, Bo:• Above the bubble-point pressure, pb, Bodecreases with increasing system pressure (effect of compressibility).• Below the bubble-point pressure, pb, Bodecreases with decreasing system pressure (less gas content at lower pressure).Gas Formation Volume Factor, Bg:• Bgdecreases with increasing system pressure (effect of compressibility)Properties of Saturated OilSolution Gas-Oil Ratio, Rs:• Above the bubble-point pressure, pb, Rsremains constant.• Below the bubble-point pressure, Rsincreases with increasing system pressure (high gas dissolution at higher pressure).Properties of Saturated OilProperties of Saturated OilTotal Formation Volume Factor, Bt:)13()( −−−−−+=gssbotBRRBBProperty Correlations for Two-Phase System• Should only be used for lack of laboratory-measured PVT data for the specific reservoir.Properties of Saturated OilReading Assignment: Chapter 3.2Two-Phase Flow in a Reservoir• Use effective permeability for inflow calculations.kkkoro=kkkwrw=kkkgrg=, , ------(3-48)Oil/Gas Relative Permeability CurvesOil/Water Relative Permeability CurvesOil Inflow Performance for a Two-Phase ReservoirVogel Correlation• It allows the use of oil properties only for a two-phase system• It uses the average pressures between wfpp,to calculate theviscosity and formation volume factor.)533(8.02.012max,−−−−−−=ppppqqwfwfoo)543(])/472.0[ln(2.1418.11max,−−−−+=srrBphkqweooooµ[ ])553(])/472.0)[ln(()(2.254)/(8.0)/(2.012−−−−+−−=srrppBppppphkqweoowfwfooµwhere, for pseudo-steady state,Substituting Eq. 3-54 into Eq. 3-53 yields,Example 3-5 Calculate Inflow Performance Using Vogel’s Correlation Develop an IPR curve for the well described in Appendix B. The drainage radius, re, is 1,490 ft and the skin effect is zero. Solution:Substituting values from Appendix B into Eq. 3-55 for yields,psi 4,336 =ip)563(8.02.0150672−−−−−−=ppppqwfwfoNext, plot pwfvs qo.Oil Inflow Performance for a Two-Phase ReservoirFor Pseudosteady State,)(tp)(2ttp=)(1ttp =max,oqGeneralize Vogel Inflow Performance• It applies to where the reservoir pressure is above bubble point and the bottomhole flowing pressure is below the bubble pointOil Inflow Performance for a Two-Phase ReservoirFlow rate, qb ,when pwf= pb:( ))573(2.141)(−−−−+−==spBppkhqDwfebµwhere pD= ln(re/rw) for steady state or = ln(0.472 re/rw).Productivity index above bubble point:)583( −−−−−=bibppqJDefine “Vogel” flow:)593(8.1−−−−=JpqbVGeneralize Vogel Inflow Performance (cont’d)Oil Inflow Performance for a Two-Phase Reservoir)613(8.02.012−−−−−−−+=bwfbwfVboppppqqqFor pwf≥ pb, For pwf≤ pb, ())603( −−−−−−−=wfioppJqNote: if , use the original Vogel correlation (Eq. 3-55)bpp ≤Fetkovich’s ApproximationOil Inflow Performance for a Two-Phase Reservoir• It was developed to improve the accuracy of Vogel’s predictions• It requires a test at two stabilized flow rates to determine the two unknowns qo,maxand