Alternating Gas-Liquid Slug Injection for Lower-Pressure Oil Recovery
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Solution Overview
Problem
Current Enhanced Oil Recovery (EOR) methods, such as Water Alternating Gas (WAG), face challenges with phase segregation and high surface injection pressures, which limit their effectiveness and efficiency.
Innovation Solution
The proposed system and method involve injecting rapidly alternating slugs of gas and liquid downhole into a subterranean well, utilizing a buffer tank to maintain consistent injection pressures and a fluid dispensing system to control the alternating slugs, thereby reducing surface injection pressure and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Water Alternating Gas (WAG) injection is used for enhanced oil recovery, then oil recovery effectiveness is improved, but surface injection pressure becomes excessively high
Solution Approach 1:
The injection process is segmented into alternating slugs of gas and liquid phases, with each phase injected for a specific duration (e.g., gas for 15-30 minutes, liquid for 5-15 minutes). This segmentation allows the system to achieve effective oil recovery through phased action while managing injection pressure by switching between phases rather than maintaining continuous high-pressure injection of a single phase.
Solution Approach 2:
The system employs periodic alternation between gas injection and liquid injection cycles. This periodic action creates a rhythmic injection pattern where high-pressure gas injection is followed by lower-pressure liquid injection, allowing the formation to absorb and distribute pressure over time. This periodic approach maintains oil recovery effectiveness while preventing sustained high surface injection pressures.
2Productivity
If Water Alternating Gas (WAG) injection is used for enhanced oil recovery, then oil recovery effectiveness is improved, but phase segregation occurs
Solution Approach 1:
The system dynamically adjusts injection parameters including phase alternation timing, injection rates, and pressure levels based on real-time formation response. This dynamic control allows the injection pattern to adapt to formation conditions, promoting better phase mixing and distribution within the reservoir while maintaining effective oil recovery. The dynamic approach prevents rigid phase separation by continuously optimizing injection characteristics.
Solution Approach 2:
The system changes key injection parameters such as phase duration, injection rate, and pressure levels during the EOR process. By varying these parameters, the system optimizes phase interaction and distribution within the formation, reducing phase segregation effects while maintaining high oil recovery effectiveness. Parameter changes allow the system to respond to formation feedback and prevent detrimental phase separation.
3Productivity
If traditional WAG injection methods are used, then oil recovery is enhanced, but energy consumption increases
Solution Approach 1:
The system utilizes the formation's own characteristics and the interacting phases to achieve enhanced oil recovery without requiring continuously high external energy input. The alternating gas and liquid phases work together synergistically, where each phase benefits from the presence and action of the other, reducing the need for high-energy continuous injection. The system essentially uses the injection process itself to create conditions that enhance recovery efficiency while reducing overall energy demands.
Solution Approach 2:
The alternating phase injection maintains continuous useful action on the oil reservoir through rhythmic gas-liquid cycles. This continuous alternation ensures that the formation is constantly subjected to beneficial injection effects without long idle periods, while the periodic nature allows pressure and energy to be distributed efficiently over time. The continuous useful action maintains oil recovery effectiveness while the periodic structure reduces peak energy requirements compared to continuous single-phase high-pressure injection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for enhanced oil recovery with reduced energy consumption and lower surface injection pressures, while also providing a cost-effective method for increasing oil recovery from existing wells without the need for expensive in-fill wells.
Implementation Method 1
a pressure control configured to maintain a specified pressure in gas reservoired within the buffer tank, and wherein the pressured gas reservoired within the buffer tank exerts a corresponding pressure on liquid reservoired within the buffer tank
Implementation Method 2
injecting rapidly alternating slugs of gas and liquid downhole into a subterranean well
Data Source
AI summary
System and method for conducting enhanced oil recovery by establishing a plurality of stacked, alternating slugs of gas and liquid travelling downhole into a subterranean well. The system can include a buffer tank including a liquid inlet through which liquid is received from a liquids source into the buffer tank, a gas inlet through which gas is received from a pressured gas source into the buffer tank, a gas outlet in fluid communication with gas reservoired in the buffer tank, and a liquid outlet in fluid communication with liquid reservoired in the buffer tank. The system can further include a pressure control configured to maintain a specified pressure in gas reservoired within the buffer tank and a fluid dispensing system in fluid communication with the gas and liquid outlets of the buffer tank.