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

1. A STUDY OF PRODUCTION OPTIMIZATION OF AN OIL WELL USING PROSPER M.Eng. Project Defence By: AadrishMir Supervisor: Dr K.C. Watts Reader: Dr D. Garagash

2. The objective of the project is first given. Well deliverability and phase behavior concepts are defined. Nodal Analysis & its applications are discussed. An introduction to PROSPER software is mentioned. A case study emphasizing on the use of production optimization of an oil well with PROSPER software is presented. Presentation Outline

3. The objective of the project is to optimize well performance in order to maximize the production rate. Oil reserves are depleting every day and oil prices are peaking, thus the role of production optimization cannot be neglected. Objective

4. Reservoir Deliverability System Well deliverability is determined by a well’s inflow performance. The Inflow Performance Relationship (IPR) is defined as the functional relationship between the production rate and the bottom hole flowing pressure. Productivity Index (PI or J) expresses the ability of a reservoir to deliver fluids to the wellbore. Productivity Ratio (PR) is the ratio of actual productivity index to the ideal productivity index where skin, s=0.

5. Phase Behaviour The reservoir fluid can be classified into basically three types i.e., single phase, two phases, or a combination. Such information is used to determine the type of IPR equation to be used. Fig 2.3 A typical p-T diagram for ordinary black oil (Ahmad, 2001).

6. A systems analysis approach, often called NODAL Analysis, has been applied to “analyze the performance of systems composed of interacting components.” Its application to well producing systems was first proposed by Gilbert (1954). Nodal Analysis

7. A partial list of possible applications of nodal analysis include: Selection of tubing size. Selection of flow line size. Analysis of an existing flow system for abnormal flow restrictions. Artificial lift design. Prediction of the effect of depletion on production capacity. Applications

8. Procedure Determine which components in the system can be changed. Select one component to be optimized. Select the node location that will best emphasize the effect of the change in the selected component. Develop expressions for the inflow and outflow. Obtain required data to calculate pressure drop versus rate for all the components. Determine the effect of changing the characteristics of the selected component by plotting inflow versus outflow and reading the intersections. Repeat the procedure for each component that is to be optimized.

10. Vertical Lift Performance (VLP) correlations for calculation of flow-line, tubing pressure loss and Inflow Performance Relationship (IPR) for the reservoir inflow.

11. SYSTEMS ANALYSIS USING PROSPER

12. Case Study of Optimization of an Oil Well Using PROSPER The well used in this case study will be designated as X-3 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 An economic limit of 1500 STB Oil/d/well was premised; i.e. producing at rates lower than that is not economical. Table 1 Reservoir Data

13. Table-5.1 PVT Data Table-5.2 Pressure Survey

14. Table-5.3 Well Data Table-5 .4Well Equipment Data

15. Develop a well performance model using PROSPER Simulate base case forecast under various operating conditions Evaluate various development options to optimize oil production Results Case Study Objectives

16. Developing a well performance model using PROSPER Table-5.5 Data entry in PROSPER

17. Fig-5.2 IPR plot Fig-5.3 Downhole equipment

18. Matching the Model Fig-5.7 VLP-IPR matching Table-5.7 Match data

19. Flow diagram for data entry and results in PROSPER

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 Simulate Base Case Forecast under Various Operating Conditions Table-5.9 Oil rates at given parameter ranges Table-5.8 Reservoir pressure & water cut ranges Table-5.10 Economic base case conditions

21. A sensitivity run on the current reservoir conditions for decreasing well head pressure (WHP) was performed. WHP can be adjusted using choke in an oil well. Reduction in WHP causes the drawdown to increase which in turn increases the oil production. Evaluate Various Development Options to Optimize Oil Production

22. Changing WHP Table-5.11 Oil rate at various WHP & WC Table5.12 Oil rate at economic water cut

23. Changing Tubing Size 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. 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. 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.

24. Changing Tubing Size, continued Table-5.13 Oil rate at various tubing internal diameter sizes

25. Gas Lifting (Artificial-Lift Method) A gas lift for X-3 was undertaken based on current conditions and engineering assumptions. 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. As the gas rate is increased the fluid velocity and therefore the friction losses also increase.

26. Gas Lifting, continued Table-5.15 Oil rate with various gas injection rates Table-5.16 Economic oil rate with optimized gas lift

27. Case Study Results Lowering the Christmas tree pressure to 100 psi is recommended because the well’s life can be extended to 70% water cut 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. 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.

28. Thank You