Methane Hydrate Foam Fracturing Reduces Surface Pressure
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Solution Overview
Problem
Hydraulic fracturing operations face challenges with foamed treatment fluids, which require lower hydrostatic pressure in the wellbore, leading to higher surface treating pressures that damage pumps and exceed their capabilities, and the use of compressed natural gas for forming hydrates is inefficient due to high storage and pumping pressures.
Innovation Solution
The method involves forming gas hydrates in situ within the wellbore using liquefied natural gas (LNG), which is vaporized and introduced into the treatment fluid, allowing foaming to occur downhole, thereby maintaining higher hydrostatic pressures and reducing surface pressure requirements, utilizing an aqueous base fluid and viscosifying agents to enhance fluid performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If foamed treatment fluids are used to reduce hydrostatic pressure in the wellbore, then the hydrostatic pressure is reduced, but the surface treating pressure increases to levels that damage pumps and exceed their capabilities
Solution Approach 1:
The patent changes the physical state of natural gas from compressed gas to liquefied natural gas (LNG), which has higher density. This parameter change increases the hydrostatic pressure contribution of the gas phase, allowing better pressure control at both surface and downhole, resolving the contradiction between reducing wellbore hydrostatic pressure and avoiding excessive surface treating pressure
Solution Approach 2:
The patent utilizes phase transition of natural gas from liquid to gas form. LNG is injected in liquid form to provide higher density and hydrostatic pressure, then converts to gas phase downhole to provide foaming effect. This phase transition enables simultaneous achievement of pressure control and foam generation, resolving the surface pressure damage issue
2Reliability
If compressed natural gas is used for forming hydrates, then hydrate formation is achieved, but high storage and pumping pressures are required
Solution Approach 1:
The patent changes the state of natural gas from compressed gas to liquefied form, which has higher density and can be stored and pumped at lower pressures. This parameter change directly addresses the high storage and pumping pressure issue while maintaining hydrate formation capability through the subsequent phase transition to gas
3Productivity
If foam quality is increased to improve fracturing performance, then fracturing effectiveness is improved, but the stability of foam in the wellbore is reduced
Solution Approach 1:
The patent utilizes controlled phase transition of LNG to gas within the wellbore. The liquid-to-gas transition occurs at specific depth and conditions, providing a mechanism to generate foam in situ while maintaining stability during transport. This resolves the contradiction by enabling foam generation where needed rather than transporting unstable foam from surface
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 effective foaming of treatment fluids within the subterranean formation while maintaining necessary pressures for fracturing, reducing equipment stress and increasing efficiency by using LNG, which is easier to store and pump than compressed natural gas, and results in improved proppant placement and fluid cleanup.
Implementation Method 1
pressurizing and then vaporizing a liquefied natural gas; introducing the thus vaporized natural gas into the treatment fluid such that gas hydrates are formed in the treatment fluid in situ within the wellbore
Implementation Method 2
introducing the treatment fluid containing the gas hydrates into a portion of the wellbore extending into the subterranean formation where the temperature and pressure of at the portion are sufficient to convert the gas hydrates into a gaseous state so as to foam the treatment fluid
Implementation Method 3
Methane hydrates improved hydrostatic pressure of foam fracturing
Data Source
AI summary
Gas hydrates are formed in treatment fluid in situ within the wellbore. Foaming of the treatment fluid can occur both during the introduction of the gas treatment fluid to form hydrates and downhole near the subterranean reservoir where the heat of the reservoir will cause the gas hydrates to revert back to a gaseous state. The method involves preparing a treatment fluid comprising an aqueous base fluid, and a viscosifying agent at the surface. This treatment fluid is then introduced into the wellbore. Also, at the surface, a liquefied natural gas is pressurized and then vaporized to produce a vaporized natural gas. The vaporized natural gas is introduced into the wellbore so as to mix with the treatment fluid also being introduced. The introduction is such that gas hydrates are formed from the natural gas in the treatment fluid in situ within the wellbore.