ContentsIntroduction1. Factors common to all enhanced recovery methods1.1. Principal influences on the efficiency of enhanced recovery1.1.1. The influence of reservoir charecteristicsa. Depthb. Dipc. Homogeneityd. Petrophysical properties

1.1.2. The influence of fluid characteristics

1.2. Linear displacement1.2.1. Frontal displacement1.2.2. Piston-like displacement

1.3. Two and three-dimensional displacement1.4. Injection well location1.4.1. Central and peripheral flooding 1.4.2. Pattern floodinga. Direct line driveb. Staggered line drivec. Five-spotd. Seven-spote. Nine-spot

1.5. Areal sweep efficiency for pattern floods1.5.1. Unit mobility ration1.5.2. Non-unit mobility ratio

Appendix 1.1. The general theory of frontal displacement (Variable cross-section)References

2. Water injection2.1. Introduction2.2. The selection of water injection as an enhanced recovery method2.2.1. Technical factors2.2.2. Economic factors

2.3. Displacement mechanics2.3.1. Homogeneous reservoirs2.3.2. Heterogeneous reservoirsa. Fissured reservoirsb. Layered reservoirsc. Reservoirs with random heterogeneities

2.4. Water injection in regularly developed homogeneous reservoirs2.5. Water injection performance calculations2.5.1. Hand calculations. Analytical methods2.5.1.1. Homogeneous reservoirsa. Buckley-Leverett theoryb. Viscous fingering theory

2.5.1.2. Layered reservoirsa. The Stiles methodb. The Dykstra-Parsons and Johnson methods

2.5.1.3. Other methods

2.5.2. Hand calculations. Empirical methods2.5.3. Mathematical models

2.6. Optimum initial free gas saturation for water injection2.7. Practical considerations in water injection projects2.7.1. Injection well completions2.7.1.1. Initial completiona. Completion of new injection wellsb. Conversation of existing production wells

2.7.1.2. Detection and selective plugging of thief zonesa. Detection of thief zonesb. Plugging agents

2.7.2. Sources and threatment of injected water2.7.2.1. Sources of injected water2.7.2.2. Water treatmenta. Treatment objectivesb. Treatment methods

2.7.2.3. Types of water injection systems

2.7.3. Pumps2.7.4. The Operation of a water injection system2.7.5. The Use of tracers to control sweep efficiency

Appendix 2.1. A study of the comparative merits of water and gas injection in the lower Gassi Touil reservoir (Ref. 4)Appendix 2.2. Practical interpretation of pressure fall-off curvesa. Introductionb. Analysis of pressure fall-off curves in reservoir filled with fluids of equal mobilityc. Hazebroek's analytical solutions for a party liquid filled reservoir

References

3. Gas injection in an oil reservoir (immiscible displacement)3.1. Introductiona. Gas injection into a gas-capb. Gas injection into an oil zone

3.2. Injection well locationa. Injection into the gas-capb. Injection into the oil zone

3.3. Sweep efficiency3.4. Preliminary studies and field evaluation of injection efficiency3.4.1. The monitoring of sweep efficiency using radioactive tracers3.4.2. Calculations based on frontal displacement theory and material balancea. Gas-cap injectionb. Oil zone injection; reservoir with no gas cap: Sgi = 0

3.5. Injection well completions3.6. Production well completions3.7. Surface installations. Compression and treatment3.7.1. Treatment methodsa. Desulphrisationb. Dehydrationc. Filtration

3.7.2. Compressor installations

3.8. Special applications of gas injection3.8.1. The formation of a secondary gas-cap3.8.2. Combined gas and water injection3.8.3. Foam injection

References

4. Miscible drive4.1. Introduction4.2. Miscible slug flooding4.3. Thermodynamic miscibility4.4. The ternary diagram4.5. Basic methods of miscible drive4.5.1. High pressure gas injection4.5.1.1. HIgh pressure natural gas injectiona. Phase conditions in the reservoirb. Miscibility pressurec. Application of high pressure natural gas injection

4.5.1.2. High pressure inert gas injection

4.5.2. Enriched gas injectiona. Description of the processb. Operating conditions

4.5.3. LPG slug injection4.5.4. Alcohol slug injection

4.6. Improved miscible drive methods4.6.1. Pre-injection of water (Ref. 3)4.6.2. Miscible slugs driven by water

4.7. Benham's correlations4.8. Model studies4.8.1. Physical models (Refs. 6 and 7)4.8.2. Mathematical models

5. Gas recycling in gas-condensate reservoirs5.1. Introduction5.2. The thermodynamics of gas recycling5.3. Sweep efficiency5.4. Well locations5.5. Production control5.6. Production equipment5.7. Determination of operating conditionsAppendix 5.1. An example of the use of mathematical models in the study of a recycling project in a gas-condensate reservoir South Kaybob Field (Canada)I. Reservoir characteristicsII. Mathematical model of unit 1a. The modelb. Computer time requiredc. Simulation results

III. Mathematical model study of units 2 and 3a. Description of the modelb. Results of the model study

References

References

6. Thermal recovery methods6.1. Date required for the study of thermal recovery methods6.1.1. the effects of temperature on hydrodynamic fluid propertiesa. Viscosityb. Relative permeability

6.1.2. The effects of temperature on the thermal and thermodynamic properties of fluids and solidsa. Thermal expansionb. Thermal capacityc. Thermal conductivityd. Latent heat of vaporization

6.1.3. Chemical reactions occuring during thermal recoverya. The thermodynamics of chemical reactions b. Chemical kinetics

6.2. Hot fluid displacement6.2.1. Basic principles (Refs. 1,11)a. Hot water displacementb. Displacement by saturated steam (Ref. 2c. A composition of displacement by cold water, hot water and steam

6.2.2. Areal sweep efficiency and stability6.2.3. Heat lossa. Heat loss from the reservoirb. In the injection well

6.2.4. Comparison of hot fluid injection techniquesa. Cyclic injection of steam possibly followed by a steamfloodb. Injection of a steam slug followed by cold waterc. Hot water displacement

6.2.5. Field applications of hot fluid injectiona. Limitations of the methodsb. Operating parametersc. Test resultsd. Field examples

6.3. In-situ combustion6.3.1. Methods of in-situ combustiona. Dry forward combustionb. Forward combustion combined with water injection ("wet combustion")c. Reverse combustion

6.3.2. Laboratory studies of in-sity combustiona. Crude oil oxidation in porous mediab. Experimental study of forward combustionc. The study of reverse combustion

6.3.3. Field application of in-situ combustiona. Advantages of the technique and its limits of applicationb. Operating methodsc. Sweep efficiency and recovery factord. Examples of field application of in-situ combustion

ConclusionReferences

7. Other methods of enhanced recovery7.1. Introduction7.2. The use of polymers7.3. Foam injection7.4. The use of surfactant solutions7.5. Micro-emulsions the maraflood project7.6. The use of carobon dioxide7.6.1. The effects of CO2 on fluidsa. Oilb. Water

7.6.2. The effects of CO2 on rock (Ref. 22 )7.6.3. Non-miscible displacement by CO27.6.4. Miscible displacement by CO27.6.5. Field applications

7.7. ConclusionsAppendix 7.1.Appendix 7.2. The rheology of polymer solutions1. viscoelasticity and relaxation time2. Laminar flow3. Flow with logitudinal strain

References

Subject Index