Expandable Annular Barriers for Low-Pressure Geothermal Fracturing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Geothermal energy extraction systems often induce seismic activity due to fracturing processes, which can prevent further fracturing and close the system, and existing methods require high pressure and are time-consuming with risks of cement failure and incomplete sealing.
Innovation Solution
A geothermal energy extraction system using expandable metal sleeves in annular barriers that abut the borehole wall, allowing for simultaneous isolation of production zones with lower fracturing pressure and without the need for cement, enabling controlled fracturing and reduced seismic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fractures are made in the formation to enable working fluid flow, then heat extraction efficiency is improved, but seismic activity increases which may prevent further fracturing and close the system
Solution Approach 1:
The patent divides the formation into multiple isolated production zones using expandable annular barriers. Each zone can be fractured and produced independently, allowing continuous operation even if one zone experiences seismic activity. The expandable barriers segment the wellbore into distinct sections, enabling targeted fracturing and isolation of seismic events to individual zones.
Solution Approach 2:
The patent uses dynamically expandable annular barriers that can be adjusted during operation. The barriers are initially collapsed during drilling and are expanded later using hydraulic pressure or mechanical actuators. This dynamic expansion allows the system to adapt to seismic events by isolating affected zones while maintaining production from unaffected zones.
2Reliability
If cement is used to seal the annulus and high pressure is applied for fracturing, then production zones can be isolated, but the process becomes time-consuming and risks cement failure and incomplete sealing
Solution Approach 1:
The patent employs disposable expandable annular barriers that are installed once and used for their intended purpose. These barriers are simpler and faster to deploy than cement operations. After serving their isolation function, they can be abandoned in place or retrieved, eliminating the need for complex cementing and curing processes.
Solution Approach 2:
The patent uses hydraulic pressure to expand the annular barriers and create isolation zones. This hydraulic expansion mechanism is faster and more reliable than cement setting, as it provides immediate sealing without requiring curing time. The hydraulic system also allows for precise control of the expansion process and easier remediation if problems occur.
3Reliability
If high pressure is used to fracture cement and create fractures, then production zones can be isolated, but the operation requires very high pressure and is time-consuming
Solution Approach 1:
The patent performs preliminary actions by installing the expandable annular barriers during the drilling operation before fracturing. The barriers are positioned and prepared in advance, so that when fracturing is needed, the zones are already isolated and ready for lower-pressure fracturing operations. This preliminary isolation eliminates the need for high-pressure cement fracturing.
Solution Approach 2:
The patent changes the physical state and properties of the isolation mechanism from rigid cement to flexible expandable barriers. This parameter change allows the system to achieve zone isolation at lower pressures and with greater flexibility. The expandable barriers can conform to the wellbore geometry and provide effective isolation without requiring the extreme pressures needed to fracture cement.
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 minimizes seismic activity, reduces the risk of cement-related failures, and increases the efficiency of fracturing by allowing for lower pressure operations and targeted fracturing, thereby enhancing the reliability and effectiveness of geothermal energy extraction.
Implementation Method 1
the expandable metal sleeve being expanded to abut a wall of the first borehole by entering pressurised fluid into the annular space through the first expansion opening
Implementation Method 2
a geothermal energy extraction subterranean system for extracting heat from a subterranean formation
Data Source
AI summary
A geothermal energy extraction subterranean system for extracting heat from a subterranean formation has an injection well in a first borehole and a first production well extracting the heated working fluid through a first production opening. The first well tubular metal structure has first and second annular barriers to isolate a production zone, each annular barrier including a tubular metal part having a first expansion opening and an outer face, an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing the wall, each end of the expandable metal sleeve being connected with the tubular metal part. The first production zone is arranged between the first and second well tubular metal structures so that the heated working fluid is extracted in the second well tubular metal structure through the first production opening.