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Enhanced Oil Recovery Case Study. MUN Reservoir Solutions. Project Details. Problem Definition : Determine the overall effect that an enhanced oil recovery technique has on a reservoir. Separate produced reservoir gas into light and heavy components for gas lift/injection
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Enhanced Oil Recovery Case Study MUN Reservoir Solutions
Project Details • Problem Definition: Determine the overall effect that an enhanced oil recovery technique has on a reservoir. • Separate produced reservoir gas into light and heavy components for gas lift/injection • Project Goals: To demonstrate how effective the technology is through reservoir simulation. • Constraints • Time • Budget not a factor – simulation-based project • Research
PVT Analysis • MUNRS was provided with produced gas and oil compositions • Test effectiveness of mixing production gas and reservoir fluid • Software: PVTsim – Fluid characterization and reservoir simulation program • Uses reservoir fluid data to perform various reservoir tests and simulate phase behaviour.
Fluid Recombination • Models a recombination of produced fluids to find original reservoir composition • Recombined fluid contains produced oil and gas at reservoir conditions. • Recombined fluid is the fluid for all tests and simulations • Minimum miscibility pressure is required to determine effectiveness of gas injection
Minimum Miscibility Pressure (MMP) • Miscibility – the ability of fluids to mix and form a homogenous solution • Allows for effective and efficient oil production • MMP - The minimum pressure for reservoir oil and gas to become miscible
Minimum Miscibility Pressure and PVTsim • MMP will be found using PVTSim for given oil and gas composition • If MMP is similar to reservoir pressure, gas injection becomes more effective • First Contact Miscibility • Multi Contact Miscibility
Initial MMP Test • Use produced gas composition to run MMP test with reservoir fluids MMP Results: • First Contact Miscibility – 980.35 bar • Multi-Contact Miscibility – 563.06 bar • Produced gas is not suitable for injection based on a reservoir pressure of 298 bar
Separator Test • Simulates the separation of reservoir fluid components at specified temperatures and pressures
Separator and MMP Test - Results • We require miscibility pressures close to reservoir pressure – 298 bar • Low pressure and low temperature tests show promising results • Further modeling is required for an optimization of results
Separator Optimization • Use recorded MMP Values for selected separator temperatures and pressures • Generate a relationship between pressure, temperature and MMP – Design Expert
Separator Optimization • Narrow the range of the pressure/temperature used in first stage of separator. • Re-model optimized MMP relationship • Use composition obtained from separator inputs shown below:
Well Down Hole Equipment • Author is Burney Waring. Image created with POVray in 1996. (http://en.wikipedia.org/wiki/File:Gaslift.jpg)
PROSPER – IPR and VLP • Inflow performance relation – psig vs STB/day • Vertical Lift Performance – psig vs STB/day • Single producer, continuous gas lift, Based on D-2H well
Gas Lift – Bottom Hole Pressure • Wanted to prove a reduction of pressure on the bottom hole • Found weight and pressure of components • Results
Prosper - VLP • Injection Rates • Injector Depth • Tubing Diameter • Tubing Roughness
Creating a Reference Case Simulation Reservoir Properties Fluid Properties Using the Norne Fluid from PVTsim Fluid Composition Critical Pressure, Temperature and Volume Using both Standard Values and Inputs from the Norne Field Porosity X-Y-Z Permeability Reservoir Temperature Reservoir Pressure
Refining the Simulation Top View 1.04 km OGC Side View 10000ft • Decrease in block size resulted in • a reduced STOOIP of ~13 MMbbls OWC 10120ft
Base-Mid-High Case Simulations Each Simulation Case uses a different injection fluid • The percentage of larger hydrocarbon chains increases as the predicted miscibility increases
Economic Analysis • Cash flows based on production
Economic Analysis • Present value of cumulative cash shows true value
Conclusions/Recommendations • Conclusions – Results show benefit from: • Gas lift • Miscible injection • Economical standpoint • Recommendations – Perform a full case study on: • Separator design • Full-Field modeling of the EOR technique