Enriched Air Injection Well for Heavy Oil Recovery
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Solution Overview
Problem
Current in-situ steam and carbon dioxide generation methods for heavy oil recovery face challenges such as poor vertical conformance, high-temperature oxidation leading to well damage, and inefficient sweep efficiency due to complex chemical reactions and heterogeneous gas/liquid reactions, which result in residual oil saturation above 20% and risk of well casing damage.
Innovation Solution
The method involves pumping a mixture of enriched air and fogged water with surfactants into the injection well, using real-time tracking of burn fronts, digital temperature surveys, and micro-seismic monitoring to prevent back burning and ignition, while recycling produced carbon dioxide to enhance oil recovery and maintain reservoir pressure, utilizing a carbon dioxide expanded fluid to remove pipe dope and rust, and creating a man-made gas cap to divert oxygen-rich gas to lower permeability layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If in-situ steam and carbon dioxide generation methods are used for heavy oil recovery, then oil viscosity is reduced and oil flow is improved, but residual oil saturation remains above 20% and sweep efficiency is poor
Solution Approach 1:
The patent changes the chemical composition parameters of the injected gas by enriching air with oxygen (achieving 15-40% oxygen concentration) and controlling carbon dioxide levels (5-20%). This parameter modification enables more effective in-situ combustion that reduces residual oil saturation below 20% while improving sweep efficiency through controlled oxidation reactions.
2Productivity
If high-temperature combustion is used to generate steam and carbon dioxide, then oil viscosity is reduced for better flow, but well casing damage occurs due to excessive heat
Solution Approach 1:
The patent implements real-time monitoring of temperature, pressure, and gas composition parameters during the in-situ combustion process. This feedback control enables adjustment of injection rates and oxygen levels to maintain combustion temperatures that reduce oil viscosity without exceeding thresholds that would damage well casings.
Solution Approach 2:
The patent controls the oxygen concentration in injected gas to range between 15-40%, which moderates the intensity of combustion reactions. This parameter control generates sufficient heat to reduce oil viscosity for improved flow while preventing excessive temperatures that would cause well casing damage.
3Productivity
If oxygen-rich gas is injected to enhance combustion, then steam generation is improved for better oil displacement, but back burning and ignition risks increase
Solution Approach 1:
The patent employs real-time monitoring of gas composition, temperature, and pressure parameters to detect conditions that may lead to back burning or uncontrolled ignition. The feedback system enables immediate adjustment of oxygen injection rates and composition to maintain safe operational parameters while preserving steam generation efficiency.
Solution Approach 2:
The patent optimizes oxygen concentration in injected gas to 15-40% rather than using pure oxygen, and controls carbon dioxide levels at 5-20%. These parameter modifications enhance combustion efficiency for improved steam generation while reducing the risk of back burning and uncontrolled ignition events.
4Ease of operation
If conventional air injection is used, then the process is simple to operate, but vertical conformance is poor and sweep efficiency is low
Solution Approach 1:
The patent modifies the composition parameters of injected gas by enriching air with oxygen to achieve 15-40% oxygen concentration and controlling carbon dioxide at 5-20%. This parameter change improves combustion efficiency and steam generation, resulting in better vertical conformance and sweep efficiency while maintaining operational simplicity through continuous gas injection.
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 reduces residual oil saturation below 20%, prevents well damage, and improves sweep efficiency by maintaining vertical conformance and controlling oxidation reactions, allowing for economic oil production rates and environmental benefits from carbon dioxide sequestration.
Implementation Method 1
a gas containing oxygen or a fluid containing hydrogen peroxide or ammonium nitrate is pumped into the injection well instead of surface generated steam. As the gaseous or fluid oxidizer is pumped into the target oil formation, a fraction of the hydrocarbon in the reservoir volume is oxidized into steam and carbon dioxide
Implementation Method 2
The coke fuel for the oxidation/high temperature combustion front is generated from the thermal cracking zone
Implementation Method 3
After ignition, the thermal front temperature will be above known heavy oil/tar ignition temperatures and self-sustaining
Implementation Method 4
As the oxidation/high-temperature combustion front continues in the reservoir, chromatographic separation will cause additional front formations. These separate zones are created from heat conduction and mass transport as well as chemical reduction and oxidation reactions occurring in the in-situ process
Data Source
AI summary
A method of oil production after water flooding includes the steps of: forming at least one injection well and at least one production well in a reservoir; pumping enriched air (at least 30-100 mole-% oxygen with fogged water droplets) into the injection well, so as to maximize gravity segregation of gas/steam and gravity drainage of oil from an attic and/or pinch-out volume of the reservoir; and recycling produced carbon dioxide by injection into a man-made gas cap created around the at least one injection well. The enriched air preferably includes a mixture of 30-100 mole-% oxygen, 0-4 mole-% argon, 0-67 mole-% nitrogen and 0-70 mole-carbon dioxide gas.