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Production performance involves matching up the following three aspects: (1)Inflow performance of formation fluid flow from formation to the wellbore. (2)Vertical lift performance as the fluids flow up the tubing to surface. (3)Choke or bean performance as the fluids flow through the restriction at surface
Designed & Presented by Mr ĐỖ QUANG KHÁNH, HCMUT 12/2010 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com Production & Completion System System analysis allows PE to both analyze production and design well completion (After Mach et al 1979) Production & Completion System Production performance involves matching up the following three aspects: (1)Inflow performance of formation fluid flow from formation to the wellbore (2)Vertical lift performance as the fluids flow up the tubing to surface (3)Choke or bean performance as the fluids flow through the restriction at surface Pressure loss distribution Production & Completion System Effect of skin on bottomhole pressure Pwf Linear flow of liquid through rock (2.1) Flow Regimes Flow Regimes - Comparison Pressure profile at location r = ri Pressure Steady-state Flow Semisteady-state Flow Unsteady-state Flow Time Time to feel boundary Assumed well is completed in a circular reservoir with drainage radius of re, then the time it takes for pressure transient to reach the boundary is: (2.2) ct is the total system compressibility IPR curves Single-phase liquid flow (2.3) (2.4) Determination of J J is determination depends on the flowing bottom-hole pressure of the test point (2.23) (2.24) Wellbore Flow Performance Pressure drop in the wellbore (2.25) Kinetic energy correction factor For most practical applications, assume W = 0, a = Work done Irreversible energy losses (2.26) Pressure drop in pipe Pressure drop for any fluid at any pipe inclination: (2.27) Flow Through Chokes Wellhead choke controls the surface pressure and production rate from a well Chokes usually are selected so the fluctuations in the line pressure downstream of the choke have no effect on the production rate Flow through the choke at critical flow conditions The flow rate is a function of upstream or tubing pressure only (downstream pressure must be approx 0.55 or less of the tubing pressure) Flow Equations Single-phase gas flow (Beggs equation): (2.28) y = ratio of the downstream pressure to the wellhead pressure Critical flow condition: (2.29) Two-phase critical flow Empirical equation: (2.30) Example: choke equation Use two-phase critical flow to estimate the flowing wellhead pressure for a given set of well conditions The well is producing 400 STB/D of oil with a gas-liquid ratio of 800 Scf/STB Estimate the flowing wellhead pressure for a choke size of 12/64 in with Gilbert’s choke equation System Analysis Inflow section: Outflow section: Inflow and Outflow performance curves System Analysis Examples System Analysis Examples Matching the Inflow and Tubing Performance Method – Reservoir and tubing pressure loss convergence in predicting bottomhole flowing pressure 33 Matching the Inflow and Tubing Performance Procedures Predict Pwf as a function of inflow flowrate q from the reservoir using either: The straight line assumptions, the productivity index and reservoir static or average pressure A radial inflow performance equation Vogel’s technique or a variant thereof Predict Pwf from pressure loss in the tubing using: Specific PTH, tubing size and length, flowing gas liquid ratio Predict PTH, tubing size and length, flowing gas liquid ratio 34 Matching the Inflow and Tubing Performance 35 Matching the Inflow and Tubing Performance Method – cumulative pressure loss from reservoir to separator IPR is the basis of pressure availability PTH will be calculated as a function of flowrate 36 ... (2.8) Gas PVT data Gas Well Performance Rawlins and Schellhardt (2.9) (2.10) Rawlins and Schellhardt analysis LOG-LOG Plot or Slope = 1/n AOF Gas flow rate qg Gas Well Performance Houpeurt... (2.12) Gas Well Performance Houpeurt (non-Darcy flow effects) (2.13) Jones, Blount, and Glaze (2.14) Graph to determine a and b or Slope = b Intercept = a Gas flow rate qg Oil Well Performance. .. Performance Vogel IPR (2.15) Fetkovich (2.16) (2.17) Oil Well Performance Jones, Blount, and Glaze (non-Darcy effects) (2.18) (2.19) Oil Well Performance Vogel’s IPR for two-phase flow (2.20)