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A Study Of Production Optimization Of An Oil Copy


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My Defence presentation for the Master\'s Project which I did with British Petroleum and presented at Dalhousie University, Canada.

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A Study Of Production Optimization Of An Oil Copy

  1. 1. A STUDY OF PRODUCTION OPTIMIZATION OF AN OIL WELL USING PROSPER<br />M.Eng. Project Defence<br />By: AadrishMir<br />Supervisor: Dr K.C. Watts<br />Reader: Dr D. Garagash<br />
  2. 2. The objective of the project is first given.<br />Well deliverability and phase behavior concepts are defined.<br />Nodal Analysis & its applications are discussed.<br />An introduction to PROSPER software is mentioned.<br />A case study emphasizing on the use of production optimization of an oil well with PROSPER software is presented.<br />Presentation Outline<br />
  3. 3. The objective of the project is to optimize well performance in order to maximize the production rate.<br />Oil reserves are depleting every day and oil prices are peaking, thus the role of production optimization cannot be neglected.<br />Objective<br />
  4. 4. Reservoir Deliverability System<br />Well deliverability is determined by a well’s inflow performance.<br />The Inflow Performance Relationship (IPR) is defined as the functional relationship between the production rate and the bottom hole flowing pressure. <br />Productivity Index (PI or J) expresses the ability of a reservoir to deliver fluids to the wellbore.<br />Productivity Ratio (PR) is the ratio of actual productivity index to the ideal productivity index where skin, s=0.<br />
  5. 5. Phase Behaviour<br />The reservoir fluid can be classified into basically three types i.e., single phase, two phases, or a combination.<br />Such information is used to determine the type of IPR equation to be used.<br />Fig 2.3 A typical p-T diagram for ordinary black oil (Ahmad, 2001).<br />
  6. 6. A systems analysis approach, often called NODAL Analysis, has been applied to “analyze the performance of systems composed of interacting components.”<br />Its application to well producing systems was first proposed by Gilbert (1954).<br />Nodal Analysis<br />
  7. 7. A partial list of possible applications of nodal <br />analysis include:<br />Selection of tubing size.<br />Selection of flow line size.<br />Analysis of an existing flow system for abnormal flow restrictions.<br />Artificial lift design.<br />Prediction of the effect of depletion on production capacity.<br />Applications<br />
  8. 8. Procedure<br />Determine which components in the system can be changed.<br />Select one component to be optimized.<br />Select the node location that will best emphasize the effect of the change in the selected component. <br />Develop expressions for the inflow and outflow.<br />Obtain required data to calculate pressure drop versus rate for all the components. <br />Determine the effect of changing the characteristics of the selected component by plotting inflow versus outflow and reading the intersections.<br />Repeat the procedure for each component that is to be optimized.<br />
  9. 9. PROSPER<br />PROSPER is a well performance, design and optimization software.<br />PROSPER is designed to allow the building of reliable and consistent well models, with the ability to address each aspect of well bore modeling viz: <br /><ul><li>Pressure Volume Temperature (PVT) fluid characterization
  10. 10. Vertical Lift Performance (VLP) correlations </li></ul> for calculation of flow-line, tubing pressure loss and Inflow Performance Relationship (IPR) for the reservoir inflow.<br />
  12. 12. Case Study of Optimization of an Oil Well Using PROSPER<br />The well used in this case study will be designated as X-3<br />The field was developed using 5 wells and reached peak production in 1996. Since then, oil production has decreased rapidly due to an increase in water content<br />An economic limit of 1500 STB Oil/d/well was premised; i.e. producing at rates lower than that is not economical.<br />Table 1 Reservoir Data<br />
  13. 13. Table-5.1 PVT Data<br />Table-5.2 Pressure Survey<br />
  14. 14. Table-5.3 Well Data<br />Table-5 .4Well Equipment Data<br />
  15. 15. Develop a well performance model using PROSPER<br />Simulate base case forecast under various operating conditions<br />Evaluate various development options to optimize oil production<br />Results<br />Case Study Objectives<br />
  16. 16. Developing a well performance model using PROSPER<br />Table-5.5 Data entry in PROSPER<br />
  17. 17. Fig-5.2 IPR plot<br />Fig-5.3 Downhole equipment<br />
  18. 18. Matching the Model<br />Fig-5.7 VLP-IPR matching<br />Table-5.7 Match data<br />
  19. 19. Flow diagram for data entry and results in PROSPER<br />
  20. 20. Since the PVT, VLP and IPR were matched to measured data, it was possible to move on and use the model to perform a system analysis<br />Simulate Base Case Forecast under Various Operating Conditions<br />Table-5.9 Oil rates at given parameter ranges<br />Table-5.8 Reservoir pressure & water cut ranges<br />Table-5.10 Economic base case conditions<br />
  21. 21. A sensitivity run on the current reservoir conditions for decreasing well head pressure (WHP) was performed.<br />WHP can be adjusted using choke in an oil well.<br />Reduction in WHP causes the drawdown to increase which in turn increases the oil production.<br />Evaluate Various Development Options to Optimize Oil Production<br />
  22. 22. Changing WHP<br />Table-5.11 Oil rate at various WHP & WC<br />Table5.12 Oil rate at economic water cut<br />
  23. 23. Changing Tubing Size<br />For further production of the remaining oil in the reservoir, adjusting the tubing size was required and sensitivity analysis of various tubing sizes (internal diameter) was performed.<br />The effect of increasing the tubing size is to give a higher node pressure for a given flow rate because the pressure drop in the tubing is decreased.<br />If the tubing is too small even though the reservoir may be capable of producing a large amount of fluid too much pressure drop occurs in the tubing.<br />
  24. 24. Changing Tubing Size, continued<br />Table-5.13 Oil rate at various tubing internal diameter sizes<br />
  25. 25. Gas Lifting (Artificial-Lift Method)<br />A gas lift for X-3 was undertaken based on current conditions and engineering assumptions.<br />The purpose of injecting gas into the tubing is to decrease the density of the flowing gas-liquid mixture and therefore decrease the required flowing bottom hole pressure.<br />As the gas rate is increased the fluid velocity and therefore the friction losses also increase.<br />
  26. 26. Gas Lifting, continued<br />Table-5.15 Oil rate with various gas injection rates<br />Table-5.16 Economic oil rate with optimized gas lift<br />
  27. 27. Case Study Results<br />Lowering the Christmas tree pressure to 100 psi is recommended because the well’s life can be extended to 70% water cut<br />The next possible option is to change the tubing size. However changing the tubing size is not recommended, since it does not produce a fruitful increment in oil production rate.<br />The gas lift method is more economically beneficial as it produces up to a maximum economic water cut of 80% with gas injection rate of 2-4 MM scf/d producing oil rates of 1800-2000 STB/d.<br />
  28. 28. Thank You<br />