Tertiary Recovery

Test Your Knowledge

Quiz: Unlocking Residual Oil: Tertiary Recovery Methods

Instructions: Choose the best answer for each question.

1. What is the primary goal of tertiary recovery methods? a) To extract oil that would otherwise remain in the reservoir. b) To increase the pressure gradient in the reservoir. c) To reduce the viscosity of water in the reservoir. d) To improve the quality of the oil extracted.

2. Which of the following is NOT a common tertiary recovery method? a) Thermal recovery b) Chemical Enhanced Oil Recovery (CEOR) c) Miscible Gas Injection d) Secondary Recovery

3. Which thermal recovery method involves burning a portion of the oil within the reservoir? a) Steam Injection b) In-situ Combustion c) Surfactant Flooding d) Carbon Dioxide Flooding

4. Which of the following is a benefit of tertiary recovery methods? a) Reduced environmental impact b) Lower investment costs c) Extended reservoir life d) Improved oil quality

5. What is a major challenge associated with tertiary recovery methods? a) Lack of technological advancements b) Low demand for extracted oil c) High investment costs d) Limited environmental impact

Exercise: Comparing Tertiary Recovery Methods

Scenario: You are an engineer working for an oil and gas company. You have been tasked with evaluating the suitability of different tertiary recovery methods for a specific reservoir. The reservoir contains heavy oil with low permeability and moderate water saturation.

Task: Based on the information provided, compare and contrast the following tertiary recovery methods in terms of their effectiveness and feasibility for this specific reservoir:

• Steam Injection:
• In-situ Combustion:
• Carbon Dioxide Flooding:
• Surfactant Flooding:

Explain your reasoning, considering the reservoir characteristics and the advantages/disadvantages of each method.

Techniques

Unlocking Residual Oil: Tertiary Recovery Methods for Enhanced Production

Chapter 1: Techniques

Tertiary recovery, or enhanced oil recovery (EOR), employs various techniques to extract residual oil left behind after primary and secondary recovery methods. These techniques focus on altering the physical properties of the oil or the reservoir itself to improve oil mobility and displacement. The key categories are:

1. Thermal Recovery: These methods increase reservoir temperature to reduce oil viscosity.

• Steam Injection: High-pressure steam is injected into the reservoir, heating the oil and significantly lowering its viscosity, making it flow more easily to the production well. Effective for heavy oil reservoirs.
• In-situ Combustion: A portion of the oil is ignited within the reservoir, generating heat to reduce viscosity. Requires specific reservoir characteristics (high permeability and oil saturation) for successful implementation. Careful control is crucial to prevent uncontrolled burning.

2. Chemical Enhanced Oil Recovery (CEOR): These techniques involve injecting chemicals to modify the reservoir fluids and improve oil displacement.

• Surfactant Flooding: Surfactants are injected to reduce the interfacial tension between oil and water. This allows smaller oil droplets to coalesce into larger ones, improving their mobility through the porous rock.
• Polymer Flooding: Polymers are added to the injected water to increase its viscosity. This improves the sweep efficiency, ensuring that the injected water displaces oil more effectively across the reservoir.
• Alkaline Flooding: Alkaline chemicals are injected to alter the pH of the reservoir fluids, affecting the interfacial tension and improving oil recovery. Often used in conjunction with other CEOR methods.

3. Miscible Gas Injection: These techniques involve injecting gases that mix (become miscible) with the oil, creating a more mobile phase.

• Carbon Dioxide (CO2) Flooding: CO2 is injected into the reservoir, dissolving in the oil and creating a miscible phase. This reduces the oil's viscosity and improves its mobility. CO2 sequestration is a potential environmental benefit.
• Nitrogen Flooding: Similar to CO2 flooding, nitrogen can be used, though generally requiring higher injection pressures for effective miscibility.

4. Microbial Enhanced Oil Recovery (MEOR): This relatively newer technique uses microorganisms to alter the reservoir conditions and improve oil recovery.

• Bacteria Injection: Specific bacteria are injected into the reservoir. They metabolize components of the crude oil, reducing its viscosity and potentially generating gases that aid in displacement.

5. Other Techniques:

• Gas Lift: Gas is injected into the wellbore to reduce pressure and improve oil flow. This isn't strictly a reservoir-wide method like the others, but a useful well-level enhancement.
• Hydraulic Fracturing: While primarily used in unconventional reservoirs, hydraulic fracturing can improve permeability in certain tertiary recovery scenarios by creating fractures in the rock matrix, allowing easier oil flow.

Chapter 2: Models

Accurate reservoir modeling is crucial for successful tertiary recovery operations. These models help predict the behavior of the injected fluids, oil displacement, and ultimate recovery. Key model types include:

• Reservoir Simulation Models: These complex models incorporate geological data, fluid properties, and injection strategies to simulate the entire process. They are used to optimize injection parameters and predict production performance. They are often coupled with geological models for increased accuracy.
• Fluid Flow Models: These models focus on the movement of fluids within the porous medium, considering factors like viscosity, pressure, and interfacial tension. They are essential for understanding the efficiency of various injection techniques.
• Chemical Reaction Models: For CEOR, models need to account for the chemical reactions between injected chemicals and reservoir fluids. These models predict the changes in fluid properties and their impact on oil recovery.
• Thermal Models: For thermal recovery, models are needed to simulate heat transfer within the reservoir, considering factors like heat capacity, conductivity, and heat losses.

Chapter 3: Software

Numerous software packages are used for tertiary recovery modeling and simulation. These tools allow engineers to design, analyze, and optimize EOR projects. Some examples include:

• CMG (Computer Modelling Group) software: A suite of reservoir simulation tools widely used in the oil and gas industry.
• ECLIPSE (Schlumberger): Another industry-standard reservoir simulator offering sophisticated capabilities for EOR modeling.
• INTERSECT (Roxar): Used for reservoir modeling and simulation, including integration with geological data.
• Specialized EOR simulation software: Many companies offer specialized software for specific EOR techniques, such as surfactant flooding or CO2 injection.
• Geostatistical software: Software like GSLIB or ArcGIS are employed to build high-quality geological models which feed into the reservoir simulators.

Chapter 4: Best Practices

Successful tertiary recovery requires careful planning and execution. Key best practices include:

• Thorough Reservoir Characterization: Detailed geological and petrophysical studies are essential to understand reservoir properties and select appropriate EOR techniques.
• Pilot Testing: Before full-scale implementation, pilot projects should be conducted to evaluate the effectiveness of the chosen EOR method and fine-tune injection parameters.
• Optimized Injection Strategies: Injection rates, patterns, and well placement need to be optimized to maximize sweep efficiency and minimize by-passing.
• Monitoring and Control: Real-time monitoring of reservoir pressure, temperature, and fluid composition is crucial to track the effectiveness of the EOR process and make necessary adjustments.
• Data Integration and Analysis: Combining data from various sources (geological, production, and monitoring data) is vital for optimizing the EOR process and interpreting the results.
• Environmental Considerations: Environmental impacts should be carefully assessed and mitigated throughout the project lifecycle, complying with all regulations.

Chapter 5: Case Studies

Several successful tertiary recovery projects demonstrate the effectiveness of these techniques. These case studies highlight the challenges, successes, and lessons learned from applying specific EOR methods in various reservoir types. Specific examples would need to be researched and added here, providing details on the techniques used, the results achieved, and the challenges overcome in each case. Examples might include:

• A case study detailing successful CO2 injection in a heavy oil reservoir.
• A case study illustrating the effectiveness of polymer flooding in a specific geological setting.
• A case study focusing on the challenges and successes of a thermal recovery project.
• A case study comparing different EOR techniques in a single reservoir.

This framework provides a comprehensive overview of tertiary recovery, suitable for expansion with detailed information for each chapter. Remember to cite sources when adding specific case studies and examples.