Cyclic Steam Injection for Ultra-Low-Permeability Shale
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Solution Overview
Problem
Existing methods are inadequate for efficiently producing hydrocarbons from ultra-low permeability shale formations due to low oil mobility, high viscosity, and flow barriers caused by polymer gels and adsorbed methane, which restrict production rates and recovery factors.
Innovation Solution
A cyclic process involving the injection of heated water vapor and solvent gases into the fracture network, followed by thermal conduction to heat the rock and fractures, allowing for thermal expansion, vaporization, desorption, and decomposition of blocking gels, without requiring high-pressure steam injection into the matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-pressure steam injection is used to heat the formation, then thermal energy is transferred to the rock and hydrocarbons, but the polymer gels and adsorbed methane create flow barriers that restrict production rates
Solution Approach 1:
The patent applies preliminary action by first removing the flow barriers (polymer gels and adsorbed methane) through chemical solvents and thermal desorption before or during the steam heating process. This preliminary removal of obstacles enables subsequent steam injection to effectively heat the formation without being blocked, thereby resolving the contradiction between heating and production rate
Solution Approach 2:
The patent extracts the harmful components (polymer gels and adsorbed methane) from the formation using chemical solvents and thermal desorption processes. By removing these flow barriers before steam injection, the system enables both effective heating and maintained production rates, resolving the technical contradiction
2Strength
If polymer-enhanced fracturing fluids are used to create hydraulic fractures, then fracture creation is improved, but polymer gels remain in the fractures and decrease permeability
Solution Approach 1:
The patent converts the harmful residual polymer gels into removable substances by introducing chemical solvents that specifically dissolve these polymers. The same polymer that provided fracture strength becomes a target for selective removal, transforming the original harm into a可控 (controllable) process that restores permeability while maintaining fracture integrity
Solution Approach 2:
The patent introduces chemical solvents as intermediary substances that selectively interact with and dissolve the polymer gels without affecting the proppant or the fracture structure. This intermediary agent enables the separation of fracture creation benefits from polymer retention harms, restoring permeability
3Stress or pressure
If pressure is reduced below bubble point at the fracture face, then gas exsolution occurs, but the exsolved gas creates a flow barrier to oil production
Solution Approach 1:
The patent applies parameter changes by modifying the pressure regime through cyclic injection and production processes. By controlling pressure fluctuations and using thermal energy, the system manages gas exsolution while maintaining conditions that prevent gas from forming a persistent flow barrier, thus preserving oil productivity despite pressure reduction
4Speed
If liquid compressibility is low compared to gas, then rapid rate decline occurs, but gas injection can carry oil components only from a small invasion depth
Solution Approach 1:
The patent merges gas injection with steam injection to combine the advantages of both methods. The gas phase provides rapid mobilization and carry-over of oil components, while the steam provides sustained thermal energy and deeper penetration into the formation. This combination resolves the contradiction by achieving both rapid production rate and deep recovery through a unified two-phase injection process
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
Enhances hydrocarbon production by increasing fluid mobility, reducing viscosity, and removing flow barriers, resulting in higher production rates and recovery factors.
Implementation Method 1
the heated water vapor and solvent gases are allowed to soak, allowing the rock to take in the heat of the steam in the fractures via thermal conduction
Implementation Method 2
thermal expansion, vaporization, desorption, and decomposition of blocking gels
Implementation Method 3
thermal expansion, vaporization, desorption, and decomposition of blocking gels
Implementation Method 4
thermal expansion, vaporization, desorption, and decomposition of blocking gels
Implementation Method 5
thermal expansion, vaporization, desorption, and decomposition of blocking gels
Data Source
AI summary
A mixture of heated water vapor, hot water, and optional solvent gases are injected into the formation through the wellhead, and the well and fracture network are filled with steam. The injection is ceased and the heated water vapor and solvent gases are allowed to soak, allowing the rock to take in the heat of the steam in the fractures via thermal conduction. The well is then opened allowing the well to produce hydrocarbons, and pressure of fluid in the fractures to drop. Oil and gas from the reservoir will then flow into the well and to the surface.