New Method Based on CO₂-Switchable Wormlike Micelles for Controlling CO₂ Breakthrough in a Tight Fractured Oil Reservoir

Abstract

CO2 is widely used for enhanced oil recovery (EOR) as a result of its high ability of washing oil and favorable injectivity, especially for a tight oil reservoir. During the EOR process, the oil recovery is significantly affected by gas channeling and the sweep efficiency of CO2 is limited. Herein, we report CO2-switchable smart wormlike micelles (WLMs) based on sodium dodecyl sulfate (SDS) and diethylenetriamine (DETA) to prevent gas channeling of CO2 in a tight fractured oil reservoir. The proof to the microstructure, formation mechanism, and plugging performance of CO2-switchable WLMs was studied by cryo-transmission electron microscopy, dynamic light scattering, nuclear magnetic resonance, rheology, and plugging property measurement. The results indicated that the system can be reversibly circulated between spherical micelles and wormlike micelles by repeatedly bubbling and removing CO2. When CO2 is introduced to the solution, part of DETA molecules is protonated and two SDS molecules are “bridged” to form a pseudo-gemini surfactant by non-covalent electrostatic attraction, behaving as a high-viscosity fluid. Upon removal of CO2, the protonated DETA molecules return to the original state, causing the pseudo-gemini structure to be destroyed and the viscosity of the fluid to be recovered. Moreover, on the basis of the results of the plugging property measurement, the solution presents conspicuous injection and plugging performance. This WLM viscoelastic fluid might have potential application in the enhancement of CO2 flooding in a tight fracture reservoir.

Aqueous CO2 Foam Armored by Particulate Matter from Flue Gas for Mobility Control in Porous Media

“…Compared with the flooding experiment with bare foam, the oil recovery by using armored foam was increased by about 18.3%. (5) For flooding experiments in the heterogeneous porous model, the mobility of fluids in the high permeability sandpack was effectively controlled by the armored foam, which increased the sweeping efficiency in the medium and low permeability sandpacks. Compared with the flooding experiment with bare COS foam, the oil recovery using armored foam was increased by about 21.3%.…”

“…This technology is considered as a crucial strategy for reducing the carbon emission from burning and consumption of fossil fuels. − In addition to the carbon sequestration in geological formations, carbon dioxide enhanced oil recovery (CO 2 -EOR) has significant advantages such as substantial drop in the interfacial tension, high solubility in crude oil, oil swelling, reduction of oil viscosity, and component extraction. However, a critical challenge for CO 2 -EOR is the low sweeping efficiency in formation, caused by CO 2 channeling and gravity segregation in porous media due to its low viscosity and low density. − This shortcoming of CO 2 -EOR can reduce the expected carbon storage volume and oil recovery in the reservoirs. In order to mitigate this problem, CO 2 foams stabilized by surfactant have been adopted to reduce CO 2 mobility. , Since the gas is wrapped into aqueous bubbles of foam, its apparent viscosity can be improved by several orders of magnitude and the viscous fingering in porous media can be inhibited.…”

Advanced Switchable Molecules and Materials for Oil Recovery and Oily Waste Cleanup

“…[ 133 ] Yang and his co‐workers also claimed that CO 2 ‐responsive WLMs formed by the combination of sodium dodecyl sulfate (SDS) and diethylenetriamine (DETA) could enhance the performance of CO 2 flooding. [ 134 ] In general, switching the fluid viscosity in situ has a significant impact on improving oil recovery and broadening reservoir processability. WLMs that contain CO 2 ‐switchable moieties are believed to have a good affinity with the CO 2 ‐EOR process.…”

Viscosity-Reducing Agents (Breakers) for Viscoelastic Surfactant Gels for Well Stimulation

“…Polymers and viscoelastic surfactants (VES) are used to improve well productivity in carbonate and sandstone reservoirs. − These compounds are used in matrix acidizing and hydraulic fracturing. ,− In matrix acidizing, polymers and VES are used as chemical diverters and are known as self-diverting agents. ,− Using diverters ensures that the low viscosity acid pumped into the well goes into the low-permeability zones and not in the high-permeability zones, thus increasing the effectiveness of matrix acidizing. ,− , Diversion by gels replaces mechanical diversion techniques because mechanical diversion methods are not always recommended, especially for long horizontal or extended-reach wells. , In hydraulic fracturing, polymers and VES act as a fracturing fluid and a proppant transporter as a result of their high viscosity. ,,,, They are pumped at or above the formation fracturing pressure to create fractures in the wellbore, thus improving well productivity, especially in low-permeability zones . However, the usefulness of gels is not only based on their diversion or fracturing abilities.…”