Pressure-Pulse Reservoir Water Injection for Formation Damage
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Solution Overview
Problem
Existing methods for reinjecting produced water into oil reservoirs face challenges such as formation damage due to high levels of solids, oils, and greases, leading to increased injection pressure, reduced injectivity, and risk to cap rock integrity, necessitating costly acidification treatments that can degrade equipment.
Innovation Solution
A method involving pressure pulses to induce fractures and plastic dilation in reservoir rock, reducing pore pressure and applying controlled pressure and flow rate variations to enhance permeability without specialized equipment, thereby mitigating formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water injection is used to increase oil recovery, then oil recovery factor is improved, but formation damage occurs due to solids, oils, and greases blocking pore space
Solution Approach 1:
The patent applies pressure pulses to induce controlled fracturing and plastic deformation in the formation, converting the harmful effect of pore blockage into beneficial fracture networks and improved permeability. The pressure pulses create tensile fractures and shear plastic zones that restore fluid flow pathways blocked by solids, oils, and greases.
Solution Approach 2:
The patent changes the pressure parameters by applying pulsating pressure regimes rather than continuous injection. The pressure pulses vary in magnitude and duration, creating dynamic stress conditions that induce fracturing and plastic deformation, thereby improving permeability and reducing formation damage.
2Productivity
If injection pressure is increased to maintain injection quota, then injection flow rate is improved, but cap rock integrity is compromised
Solution Approach 1:
The patent uses periodic pressure pulses rather than continuous high pressure. The pulsating action allows the formation to undergo controlled fracturing and plastic deformation during high-pressure phases, followed by relaxation during low-pressure phases, thereby maintaining injection capability while preserving cap rock integrity through cyclic rather than sustained stress.
Solution Approach 2:
The patent applies preliminary pressure pulses to create fracture networks and plastic zones before maintaining steady-state injection. This preliminary mechanical stimulation prepares the formation by creating pathways and reducing stress concentration points, allowing subsequent injection at lower pressures that preserve cap rock integrity.
3Productivity
If acidification treatment is applied to restore injectivity, then formation damage is removed, but equipment degradation occurs due to corrosion
Solution Approach 1:
The patent replaces the chemical acidification system with a mechanical pressure pulse system. Instead of using acid to dissolve formation damage, the patent applies mechanical pressure pulses to induce fracturing and plastic deformation, physically opening blocked pores and creating new flow pathways without chemical corrosion of equipment.
Solution Approach 2:
The patent uses a simple, inexpensive pressure pulse system that can be implemented with standard injection equipment, replacing the expensive and complex acidification system requiring specialized vessels and chemicals. The mechanical method uses readily available energy sources to achieve the same injectivity restoration without the equipment degradation risks of acid treatment.
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
Increases well injectivity and oil/gas production, reduces the need for acidification operations, and preserves equipment integrity, while being cost-effective and resource-efficient.
Implementation Method 1
applying a pressure pulse with the aim of inducing, in a controlled manner, fractures and plastically mobilized regions in the reservoir rock
Implementation Method 2
plastically mobilized regions in the reservoir rock
Implementation Method 3
The plasticity theory for rocks states that the shear plastic deformation results in plastic dilation proportional to the dilation angle of the material, that is, when the shear strength of the porous medium is exceeded, the material plastically dilates, which can increase its porosity and permeability
Implementation Method 4
reducing the reservoir pore pressure in the vicinity of the injection well
Implementation Method 5
the shear plastic deformation results in plastic dilation proportional to the dilation angle of the material, that is, when the shear strength of the porous medium is exceeded
Implementation Method 6
friable formations disaggregate when their shear strength is exceeded, resulting in the rearrangement and transport of solids
Data Source
AI summary
The present disclosure describes a method of injecting water, whether captured or produced during oil processing, into oil reservoirs with geomechanical stimulation by pressure pulse.