Supercritical CO2 Fluidity Control via Nano-Silica Microemulsion
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Solution Overview
Problem
Existing carbon dioxide fluidity control technologies face challenges in ultra-low permeability oil reservoirs due to instability and limited range of foam technology, with nanoparticles requiring water dissolution and facing agglomeration issues, leading to low injection capacity and high operational costs.
Innovation Solution
A device and method using a surfactant and compatible nanoparticles to create a stable microemulsion of supercritical carbon dioxide and nano-silica, which is injected into oilfield wells, forming a gas-in-water foam that enhances fluidity control and stability, particularly in ultra-low permeability reservoirs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foam technique is used for carbon dioxide fluidity control, then fluidity control effect is improved, but foam stability deteriorates due to thermodynamic instability
Solution Approach 1:
The patent introduces solid particles as an intermediary substance that adsorbs at the gas-liquid interface of foam bubbles. These particles act as a mediator that stabilizes the foam structure by reducing surface energy and preventing bubble coalescence, thereby maintaining foam stability during migration in the stratum while preserving the fluidity control effect.
Solution Approach 2:
The patent creates a composite foam system by combining carbon dioxide gas, liquid phase (water or surfactant solution), and solid particles. This composite structure leverages the properties of all three phases: the gas provides expandability, the liquid provides continuity, and the solid particles provide stability, resolving the contradiction between foam effectiveness and stability.
2Stability of the object's composition
If nanoparticles are dissolved in water phase for injection, then foam stability is enhanced, but nanoparticle agglomeration and adsorption on rock wall surface increases
Solution Approach 1:
The patent changes the physical state parameter of nanoparticles from dissolved state in water to suspended state in oil phase. This parameter change prevents agglomeration and adsorption on rock surfaces while maintaining foam stability, as the nanoparticles remain dispersed in the oil carrier and are delivered to the foam interface where they are needed.
Solution Approach 2:
The patent introduces oil as an intermediary carrier medium that transports nanoparticles to the target location. The oil phase prevents direct contact between nanoparticles and water/rock surfaces, reducing agglomeration and adsorption losses, while still allowing nanoparticles to reach the gas-liquid interface for foam stabilization.
3Reliability
If water or surfactant aqueous solution is injected into ultra-low permeability reservoirs, then fluidity control is achieved, but injection capacity decreases due to high injection pressure
Solution Approach 1:
The patent changes the continuous phase from water or surfactant aqueous solution to oil phase. This parameter change significantly reduces injection pressure requirements because oil has better flow characteristics and lower interfacial tension with carbon dioxide, enabling effective fluidity control in ultra-low permeability reservoirs while maintaining high injection capacity.
Solution Approach 2:
The patent utilizes phase transition by using oil as the continuous phase that can easily mix with and carry carbon dioxide. The oil-carbon dioxide mixture forms a stable foam structure upon contact with formation water, achieving fluidity control with much lower injection pressures than aqueous-based systems.
4Productivity
If supercritical carbon dioxide is used for oil displacement, then extraction efficiency is improved, but premature gas channeling occurs due to low viscosity
Solution Approach 1:
The patent creates a composite system by dissolving surfactant in supercritical carbon dioxide to form a surfactant-enhanced carbon dioxide (SEC02) mixture. This composite material maintains the high extraction efficiency of supercritical carbon dioxide while the surfactant reduces gas viscosity and prevents premature channeling by improving wetting characteristics and stabilizing the displacement front.
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
The method improves the injection capability and stability of carbon dioxide fluidity control, allowing for effective oil extraction in ultra-low permeability reservoirs by forming a stable foam that interacts with stratum water and adsorbs on the gas-liquid interface, increasing the timeliness and efficiency of fluidity control.
Implementation Method 1
both the temperature and the pressure of most reservoirs are above the critical point of carbon dioxide, so that the carbon dioxide often exists in a supercritical state after arriving at the stratum
Implementation Method 2
forming a gas-in-water foam that enhances fluidity control and stability
Implementation Method 3
create a stable microemulsion of supercritical carbon dioxide and nano-silica
Implementation Method 4
adsorbs on the gas-liquid interface, increasing the timeliness and efficiency of fluidity control
Implementation Method 5
forming a gas-in-water foam that interacts with stratum water
Data Source
AI summary
Provided is a carbon dioxide fluidity control device comprising, a sample preparation tank, a high-pressure stirring unit, a reciprocating plunger pump and a booster pump, wherein the stirring unit comprises one or more high-pressure stirring tanks, each provided with an atomizing spray probe and a piston, wherein a discharge port of the sample preparation tank is connected to the atomizing spray probe via a plunger pump, which is connected to the piston to push the piston to reciprocate; the booster pump is connected to the high-pressure stirring tanks to provide supercritical carbon dioxide to the high-pressure stirring tank; and a discharge port of the high-pressure stirring tanks is connected to an oilfield well group. Provided is a carbon dioxide fluidity control method using the device, comprising mixing surfactants and nanoparticles with heated carbon dioxide, and injecting a microemulsion of supercritical carbon dioxide and nano-silicon dioxide into an oilfield well group.