Downhole Electrical Steam Generation for Heavy Oil
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Solution Overview
Problem
Deep or low-injectivity heavy oil formations often experience energy loss during steam delivery from surface boilers, leading to inefficient steam stimulation, as conventional downhole steam generators face complexities in installation, monitoring, and high costs due to reliance on combustion-based systems.
Innovation Solution
A method for downhole steam generation involving the determination of desired electrical conductivity for water, mixing feedwater with sidestreams to achieve the desired conductivity, and passing an electrical current through the water to generate steam, utilizing electrodes and varying flow rates to produce high-pressure steam with a controlled mass fraction of vapor, while also enabling hydrogen and oxygen production through electrolysis for enhanced oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional surface boilers are used to generate steam for deep or low-injectivity formations, then steam can be delivered to the formation, but substantial energy loss occurs during delivery and the system becomes complex
Solution Approach 1:
The patent replaces the mechanical combustion-based steam generation system with an electrical heating system. Instead of using burners and combustion chambers to generate steam downhole, the invention uses electrical resistance heating elements that are simpler to install and control, thereby reducing system complexity while maintaining steam generation capability for deep or low-injectivity formations
Solution Approach 2:
The patent introduces water as an intermediary medium to transfer heat from the electrical heating elements to the formation. The water circulates through the wellbore, absorbing heat from the electrical heaters and delivering it to the formation via injection, which simplifies the overall system by using a familiar heat transfer medium instead of direct combustion products
2Ease of operation
If combustion-based downhole steam generators are used, then steam can be generated at the wellbore, but installation, monitoring, and control become difficult and costs increase
Solution Approach 1:
The patent replaces complex combustion-based mechanical systems with simpler electrical heating elements that can be easily installed using standard electrical wellhead connections. The electrical system requires no combustion chambers, burners, or complex fuel delivery mechanisms, making installation and monitoring straightforward while reducing operational costs through simpler equipment and easier control
Solution Approach 2:
The electrical heating system is inherently self-regulating through standard electrical controls, eliminating the need for complex combustion control systems. The heating elements can be independently controlled and monitored through standard electrical meters and controls, making the system self-managing without requiring sophisticated monitoring infrastructure or specialized operational knowledge
3Productivity
If water with high electrical conductivity is used for steam generation, then steam generation efficiency increases, but dissolved solids cause scaling and deposition problems
Solution Approach 1:
The patent extracts and removes dissolved solids from the water supply through pre-treatment systems before the water enters the steam generation system. By taking out the harmful dissolved solids through filtration, softening, or demineralization processes, the system maintains high electrical conductivity for efficient steam generation while preventing scaling and deposition problems in the heating elements and wellbore
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 efficiently generates steam with a controlled quality, reducing energy loss and operational costs, and allows for cyclic operation, enhancing oil production by moderating formation temperatures and reducing viscosity through hydrogen and oxygen injection, thus overcoming the limitations of conventional steam generation methods.
Implementation Method 1
Direct electrical steam generation for downhole heavy oil stimulation... passing an electrical current through the resultant stream in the downhole location to generate steam
Implementation Method 2
enabling hydrogen and oxygen production through electrolysis for enhanced oil recovery
Data Source
AI summary
A method of downhole steam generation comprising determining a desired level of electrical conductivity for water to be converted to steam in a downhole location, acquiring a main feedwater supply, wherein water of the main feedwater supply has an electrical conductivity lower or higher than the desired level, mixing water of the main feedwater supply with water from one or more sidestreams to generate a resultant stream with an electrical conductivity of about the desired level, pumping the resultant stream to the downhole location, and passing an electrical current through the resultant stream in the downhole location to generate steam.