Modified Nonionic Surfactant Emulsion for CO2 Sweep Efficiency
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Solution Overview
Problem
Enhanced oil recovery techniques using carbon dioxide often suffer from poor sweep efficiency due to carbon dioxide's low viscosity and density, leading to bypassing of oil reservoirs and early breakthrough, which reduces the effectiveness of viscosity reduction and oil recovery.
Innovation Solution
A modified nonionic surfactant formulation with a pour point depressant is injected into the oil reservoir, forming an emulsion with carbon dioxide that increases apparent viscosity, inhibiting flow through high permeability zones and directing carbon dioxide to unswept areas, thereby improving sweep efficiency and oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If carbon dioxide is injected into the oil containing reservoir, then the viscosity of oil is reduced to increase flow to production wellbore, but poor sweep occurs due to low viscosity of carbon dioxide causing it to flow through paths of least resistance and bypass significant portions of the reservoir
Solution Approach 1:
A surfactant solution is introduced as an intermediary substance between the carbon dioxide and the oil reservoir. The surfactant forms an emulsion with the carbon dioxide, creating a modified injective fluid that maintains the viscosity-reducing benefits of carbon dioxide while preventing it from channeling through high-permeability paths. The surfactant acts as a mediator that modifies the flow characteristics of carbon dioxide, enabling it to sweep through previously unswept portions of the reservoir.
Solution Approach 2:
The physical parameters of the injective fluid are changed by modifying the carbon dioxide through emulsion formation with surfactant. This changes the viscosity, density, and flow characteristics of the carbon dioxide, transforming it from a low-viscosity gas that channels easily into a modified fluid with enhanced sweep efficiency. The parameter changes enable the carbon dioxide to contact and reduce the viscosity of oil in previously inaccessible reservoir zones.
2Speed
If carbon dioxide is injected into the oil containing reservoir, then oil viscosity is reduced, but early breakthrough occurs due to low density of carbon dioxide causing it to rise to the top and bypass oil-containing zones
Solution Approach 1:
The surfactant solution serves as an intermediary that modifies the density and flow behavior of carbon dioxide. By forming an emulsion, the surfactant increases the effective density of the carbon dioxide stream, preventing it from rapidly rising to the top of the reservoir. This intermediary modification ensures that carbon dioxide remains in contact with oil-containing zones longer, delaying breakthrough and improving overall recovery efficiency.
3Reliability
If a surfactant is used to generate an emulsion in the oil containing reservoir, then the apparent viscosity increases to block carbon dioxide flow through previously swept areas, but the formulation complexity increases
Solution Approach 1:
The formulation parameters of the surfactant solution are optimized to achieve the desired emulsion characteristics. By adjusting the surfactant concentration, molecular structure, and formulation composition, the system achieves the appropriate balance between emulsion stability and formulation simplicity. The parameter optimization ensures that the surfactant effectively modifies carbon dioxide flow while maintaining practical formulation requirements.
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 modified nonionic surfactant formulation enhances oil recovery by forming stable emulsions that reduce viscous fingering and gravity override, increasing the contact between carbon dioxide and oil, leading to improved oil extraction efficiency and extended reservoir life.
Implementation Method 1
an emulsion of the carbon dioxide and the nonionic surfactant can be formed in an aqueous solution in the oil containing reservoir
Implementation Method 2
the modified nonionic surfactant formulation including a nonionic surfactant and a pour point depressant
Data Source
Figure 1A~1B
Figure 1C
AI summary
Embodiments of the present disclosure include modified nonionic surfactant formulations having a nonionic surfactant and a pour point depressant, where the modified nonionic surfactant formulations have a pour point of -3 °C to -54 °C. In one or more embodiments, the modified nonionic surfactant formulations can be introduced into a flow of carbon dioxide, where the flow of carbon dioxide and the modified nonionic surfactant formulation are injected into an oil containing reservoir. In one or more embodiments, an emulsion of the carbon dioxide and the nonionic surfactant form in the oil containing reservoir, where the use of the pour point depressant provides minimal interference in forming the emulsion.