Electrical Heating of Oil Shale Formations
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Solution Overview
Problem
Current methods for heating subterranean hydrocarbon formations, such as oil shale, face challenges in thermal diffusion and uniformity, particularly in deep or shallow heavy oil formations, where steam-assisted recovery is impractical or environmentally problematic.
Innovation Solution
A method involving the placement of electrodes in distinct wellbores adjacent to target intervals with lower electrical resistance than pay intervals, injecting AC electrical current to heat the target intervals, which then conduct heat to the pay intervals through thermal conduction, enhancing hydrocarbon production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal diffusion heating is used from boreholes, then the heating method is simple to implement, but the heating rate is too slow and heat spreads only a few meters per month
Solution Approach 1:
The patent replaces the mechanical thermal diffusion heating system with an electromagnetic heating system. Electromagnetic waves at selected frequencies directly heat the formation through dielectric heating, substituting the slow thermal conduction process with rapid electromagnetic energy transfer, thereby achieving fast heating rates while maintaining operational simplicity.
Solution Approach 2:
The patent changes the fundamental heating parameter from thermal conduction to electromagnetic radiation. By operating at specific resonant frequencies of the formation, the system achieves rapid heating through dielectric loss mechanisms, transforming the heating rate from meters per month to much faster rates while keeping the system relatively simple to deploy.
2Manufacturing precision
If electromagnetic heating is used with monopole antennas, then heating is distributed in the formation, but the skin depth limits penetration to about 1 meter at 3 MHz
Solution Approach 1:
The patent transitions from one-dimensional borehole heating to three-dimensional volumetric heating by utilizing electromagnetic wave propagation through the entire formation volume. Multiple antennas positioned at different locations create overlapping electromagnetic fields that distribute heating uniformly throughout the target zone, achieving both deep penetration and uniform distribution simultaneously.
Solution Approach 2:
The patent employs a multi-antenna system where each antenna serves multiple functions: individual antennas can be tuned to different frequencies to target specific depth zones, while collectively they provide uniform distributed heating across the entire formation. This multi-functional approach allows the system to achieve both deep penetration and uniform heating distribution.
3Temperature
If steam injection is used for heavy oil recovery, then the temperature can be maintained, but steam breaks through to the surface in shallow formations or cannot be maintained in deepwater plays
Solution Approach 1:
The patent replaces the mechanical steam injection system with an electromagnetic heating system. Electromagnetic waves directly heat the formation and heavy oil in place, eliminating the need for steam generation, injection, and circulation infrastructure. This substitution provides reliable temperature maintenance in both shallow formations and deepwater plays where steam systems fail.
Solution Approach 2:
The patent uses electromagnetic energy as an intermediary to transfer heat to the formation. Instead of injecting steam that must physically travel through the formation, electromagnetic waves penetrate directly and convert energy to heat through dielectric heating, providing reliable temperature control without the limitations of steam transport.
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 efficient and uniform heating of hydrocarbon formations, reducing viscosity of heavy oils and converting kerogen to shale oil and gas, with minimal environmental impact and no need for further refining, suitable for both shallow and deep formations.
Implementation Method 1
Electrical current is injected into the at least one target interval in order to heat the at least one target interval and heat the pay interval
Implementation Method 2
heat the pay interval by thermal conduction
Data Source
AI summary
A method (and system) is provided that enhances production of hydrocarbons from a subterranean formation by identifying at least one target interval of the subterranean formation that is in proximity to a pay interval, wherein the at least one target interval has an electrical resistance less than electrical resistance of the pay interval. A plurality of electrodes are placed in positions spaced apart from one another and adjacent the at least one target interval. Electrical current is injected into the target interval by supplying electrical signals to the plurality of electrodes. The electrical current injected into the at least one target interval passes through at least a portion of the at least one target interval in order to heat the at least one target interval and heat the pay interval by thermal conduction for enhancement of production of hydrocarbons from the pay interval.