Direct-Contact Steam Generator for Enhanced Oil Recovery
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Solution Overview
Problem
Existing systems for generating superheated steam for enhanced oil recovery are complex, expensive, and cumbersome, particularly for portable applications, and fail to provide a controllable combination of single or two-phase steam with or without flue gases, leading to energy losses and corrosion issues due to concentrated dissolved solids.
Innovation Solution
A direct-contact steam generator or superheater system capable of operating on feedwater in liquid or gas states, with a refractory-lined combustion chamber and programmable logic control for varying fuel and oxidizer inputs, allowing for the generation of superheated steam with a controlled flue gas to steam ratio, and incorporating cooling methods to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a direct contact steam generator is used to inject flue gases with steam, then the drive mechanism for moving mobilized oil is improved, but the system becomes complex, expensive, and cumbersome for portable applications
Solution Approach 1:
The system is divided into separate functional modules: a portable steam generator that produces saturated steam, and a downhole superheater section that converts it to superheated steam with flue gas injection. This segmentation allows the surface equipment to remain simple and portable while achieving complex downhole steam modification through the superheater section in the injection tubing.
Solution Approach 2:
Saturated steam acts as an intermediary carrier that transports energy from the portable surface generator to the downhole superheater section. The superheater section then uses this steam as a medium to generate superheated steam with flue gas injection, effectively decoupling the complexity of flue gas handling from the portable surface equipment.
2Productivity
If superheated steam is generated to reduce heavy oil viscosity and improve permeability, then oil flow is enhanced, but the system requires complex hardware that is not portable
Solution Approach 1:
The superheating and flue gas injection functions are segmented and placed downhole in the injection tubing, while the surface steam generator remains simple and portable. This allows superheated steam generation benefits to be achieved without adding complexity to the portable surface equipment.
Solution Approach 2:
The downhole superheater section utilizes the kinetic energy and thermal energy of the injected saturated steam to drive the superheating process and flue gas injection automatically, without requiring additional complex surface equipment or external power sources at the wellsite.
3Device complexity
If once-through steam generation is used, then the system is simpler, but steam quality is limited to no higher than 80% and dissolved solids concentrate in the liquid phase
Solution Approach 1:
Saturated steam serves as an intermediary that carries water vapor free of dissolved solids from the simple once-through surface generator to the downhole superheater. This allows the use of simple once-through generation technology while achieving high-quality superheated steam downhole, as the steam quality is determined at the superheater rather than the surface generator.
4Stress or pressure
If flue gases are vented to the atmosphere from a once-through boiler, then combustion can be carried out at low pressure, but energy is lost and dissolved solids concentrate causing corrosion
Solution Approach 1:
The flue gases that would normally be wasted are captured and injected downhole with the steam, converting a harmful waste product into a beneficial drive mechanism for oil recovery. The energy that would be lost is now utilized to provide additional heating and drive pressure in the reservoir.
Solution Approach 2:
The steam acts as an intermediary that carries the flue gases from the surface combustion chamber to the downhole injection point, enabling the flue gases to be utilized productively rather than vented to the atmosphere.
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
The system enables efficient, adaptable, and portable generation of superheated steam with controlled flue gas injection, reducing energy losses and corrosion, while maintaining high steam quality and flexibility for various field conditions, enhancing oil recovery and reducing operational complexity.
Implementation Method 1
pressurized water is injected into the pressurized hot combustion flue gases directly. This results in vaporization of some fraction of the water
Implementation Method 2
pressurized water is injected into the pressurized hot combustion flue gases directly. This results in vaporization of some fraction of the water, depending on relative flow rates
Implementation Method 3
a superheater section which receives the water vapor or liquid water and superheats it to a desired temperature by direct contact with combustion flue gases
Implementation Method 4
A direct-contact steam generator or superheater system capable of operating on feedwater in liquid or gas states, with a refractory-lined combustion chamber
Data Source
AI summary
Systems and methods are disclosed for producing a superheated steam having a specified ratio of water vapor to combustion gases for injection into a well to enhance heavy oil production. Embodiments comprise indirect-contact steam generators and direct-contact steam generators.