Geothermal Reservoir Interval Isolation for Deep Fracture Stimulation
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Solution Overview
Problem
In Enhanced Geothermal Systems (EGS), a significant portion of the subterranean formation remains unstimulated due to higher fracture initiation pressures at greater depths, leading to low energy recovery efficiency and high drilling costs, as only a small section of the open-hole section is fractured, while deeper regions with higher pressures remain untapped.
Innovation Solution
The method involves isolating selected subterranean open-hole intervals using temporary fracture sealants, high viscosity fluids, high pressure jet nozzles, high temperature inflatable or expandable packers, and scab liners to stimulate and seal fractures, allowing for targeted stimulation of unstimulated fractures without propagating sealed fractures, thereby maximizing energy recovery without the need for continuous drilling rig presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water pressure is applied to create fractures in the open-hole section, then fractures are created in the section with lowest fracture initiation pressure, but only a small section is fractured and deeper regions with higher pressures remain unstimulated
Solution Approach 1:
The open-hole section is divided into multiple isolated intervals using packers and temporary plugging devices. Each interval can be stimulated independently by applying water pressure separately, allowing fractures to be created in deeper high-pressure zones without being limited by the lowest fracture initiation pressure zone. This segmentation enables selective stimulation of previously inaccessible regions.
Solution Approach 2:
Packers and temporary plugging devices are installed in advance to isolate specific intervals before fracture stimulation. This preliminary isolation ensures that when water pressure is applied, the energy is concentrated in the target interval rather than propagating fractures to the lowest pressure zone, enabling successful stimulation of deeper zones with higher fracture initiation pressures.
2Ease of manufacture
If the number of wells is reduced to lower project costs, then drilling and completion costs decrease, but energy recovery efficiency per well must be maximized
Solution Approach 1:
By segmenting the wellbore into multiple isolatable intervals, a single well can stimulate multiple previously inaccessible zones that would have required separate wells. The packer system allows each interval to be treated as an independent stimulation target, effectively multiplying the productivity per well and reducing the total number of wells needed for a given energy recovery goal.
Solution Approach 2:
The system changes the pressure distribution parameters by isolating intervals and applying pressure locally. This allows stimulation of zones with higher fracture initiation pressures that would not be accessible in a conventional single-zone stimulation approach, thereby increasing energy recovery per well without requiring additional wells.
3Productivity
If temporary fracture sealants and isolation devices are used to isolate intervals, then targeted stimulation of unstimulated fractures is enabled, but device complexity increases
Solution Approach 1:
Temporary plugging devices and fracture sealants are used as disposable isolation elements that are installed to enable targeted stimulation and then abandoned in place after serving their purpose. These inexpensive temporary devices create the necessary isolation without requiring complex permanent infrastructure, allowing the system to achieve high productivity while keeping device complexity manageable through the use of simple, replaceable components.
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 increases energy recovery by stimulating previously unaccessible fractures, reduces the number of wells required, and lowers project costs by efficiently isolating and stimulating deeper, high-pressure zones, thereby enhancing the overall efficiency and cost-effectiveness of power generation from geothermal reservoirs.
Implementation Method 1
high pressure jet nozzles to stimulate and seal fractures
Implementation Method 2
high pressure jet nozzles to stimulate and seal fractures
Implementation Method 3
high viscosity fluids, high pressure jet nozzles, high temperature inflatable or expandable packers
Implementation Method 4
high temperature inflatable or expandable packers
Implementation Method 5
high temperature inflatable or expandable packers
Implementation Method 6
Water is circulated from an injection well, through the fractures where it is heated. The hot water or heat from the formation is produced from one or more production wells
Implementation Method 7
Water is circulated from an injection well, through the fractures where it is heated
Data Source
AI summary
Systems and methods can include maximizing energy recovery from a subterranean formation. According to one embodiment, a selected subterranean open-hole interval is isolated and at least one fracture is stimulated in the isolated subterranean open-hole interval.