Water Flooding Patterns

Water flooding is a vital enhanced oil recovery technique aimed at maximizing crude oil extraction. The first step in designing a water flooding project is selecting the appropriate flood pattern to ensure optimal contact between the injection fluid and the crude oil system.

Flood Pattern Selection

The objective is to choose a pattern that allows the injection fluid to maximize contact with the oil. This can be achieved by:

1. Converting Existing Production Wells: Turning some production wells into injection wells.
2. Drilling Infill Injection Wells: Adding new wells to enhance fluid distribution.

The suitability of the flooding pattern depends on the number and location of existing wells in the reservoir.

Factors Influencing Flood Pattern Selection

When selecting a flooding pattern, consider the following factors:

1. Reservoir Heterogeneity: Variations in rock properties and composition.
2. Directional Permeability: Flow characteristics that affect fluid movement.
3. Direction of Formation Fractures: Orientation can significantly impact flow patterns.
4. Availability of Injection Fluid: The type of fluid available (gas or water).
5. Desired and Anticipated Flood Life: Longevity of the flooding project.
6. Maximum Oil Recovery: The overall goal of the flooding operation.
7. Well Spacing: The distance between wells affects efficiency.
8. Productivity and Injectivity: Performance metrics of the wells involved.

Types of Well Arrangements (Water Flooding Patterns)

1. Irregular Injection Patterns

Caused by:

• Slant-hole drilling techniques.
• Limited small reservoirs with fewer wells.
• Faulting within the reservoir.
• Localized variations in porosity or permeability.

1. Peripheral Injection Patterns

• Injection wells are situated at the external boundary of the reservoir, displacing oil toward the center.
• Advantages: Maintains pressure effectively. Efficiently sweeps oil toward production wells.

1. Regular Injection Patterns

Includes various arrangements such as:

• Direct line drive.
• Staggered line drive.
• Four spot, five spot, seven spot, and nine spot configurations

1. Crestal and Basal Injection Patterns

• Crestal Injection: Injection occurs through wells at the top of the structure.
• Basal Injection: Fluid is injected at the bottom of the structure.
• Advantages: Many water injection projects benefit from basal injection patterns, utilizing gravity segregation to enhance oil recovery.