Crude Oil Recovery with Duomeen CTM-Stabilized Supercritical CO₂ Foams for HPHT and Ultrahigh-Salinity Carbonate Reservoirs

Abstract

The compatibility of an amine-based foaming agent, Duomeen CTM [C 12−14 N(CH 3 )C 3 N(CH 3 ) 2 ], and crude oil on supercritical CO 2 foam transport are evaluated for a carbonate reservoir with high pressure and high temperatures (HPHT) and ultrahigh salinities. The CTM solubility in the formation brine (FB) with ultrahigh salinity is evaluated as a function of temperature and pH. CTM is a switchable surfactant, whereby it is soluble in FB when its pH is adjusted to or below a critical pH where protonation has occurred. The thermal stability of CTM at pH 6 was demonstrated at 135 °C with an oxygen scavenger. The adsorption of CTM was evaluated on pure calcite and reservoir carbonate rock. CTM adsorption was determined to be low on calcite, but moderate on reservoir carbonate, due to the presence of siliceous minerals. As expected, the phase behavior of protonated CTM in FB at pH = 4 with crude oil was characteristic of a Winsor Type I phase. The surfactant preferentially propagates with the aqueous phase in the presence of crude oil. The CTM foamability was evaluated in Indiana limestone cores in the: (1) absence of crude oil in a water-wet core, (2) presence of residual oil in a mixed-wet core, and (3) presence of residual oil in oil-wet cores. The foam strength remained stable with 13% residual oil in a mixed-wet core without requiring a minimum pressure gradient (MPG) for starting foam generation. However, at a higher residual oil saturation of 20% in an oil-wet core, the foam strength weakened significantly, and a MPG of 3 psi/ft was necessary for foam generation. These findings provide a framework for the application of CTM-based foams to provide CO 2 mobility control and recover crude oil in carbonate reservoirs at HPHT conditions.

Probing the Effect of Wettability on Transport Behavior of Foam for Enhanced Oil Recovery in a Carbonate Reservoir

“…It also has been reported that the MPG is largely dependent on wettability and oil saturation. At oil-wet condition, a higher MPG, or correspondingly a higher flow rate may be needed in order for foam to be readily generated . When the surfactant concentration is 0.2 wt %, however, foam still cannot be generated by increasing the flow rate up to 15 ft/d based on the pressure gradients at steady states (Section S.5 in the Supporting Information).…”

“…Foam enhanced oil recovery (EOR) has been extensively applied in the oil field to ameliorate the challenges of viscous fingering, gravity segregation, and channeling encountered during gas flooding. − As for foam flow in porous media, the lamellae may be intermittently generated by snap-off, lamellae division, and leave behind, while it can also be easily collapsed due to gravity and high capillary pressure. , The foam strength, i.e., foam apparent viscosity, is largely dependent on in situ foam generation and the foam stability in porous media. , Two distinct regimes, namely, the low-quality regime and the high quality regime, have been observed in the strong foam state . The high quality regime foam has attracted greater interests due to the concern of high surfactant cost …”

“…It is also widely acknowledged that the oil-wet condition is not favorable for in situ foam generation or foam stability. − However, whether foam can be generated under oil-wet conditions remains controversial. − Although most of the foam flooding results performed in the laboratory are promising, the foam EOR process can easily fail in field applications, which may be possibly due to an underestimation of the oil destabilization effect on foam in the lab and the limitation of injectivity in the field. , In the presence of crude oil, the MPG for foam generation may be also increased . After a survey of the literature, it is found that most of the core flooding tests are performed under water-wet or intermediate wet conditions, which may also overestimate the strength of foam in the presence of oil for carbonate reservoirs.…”

A Review on Foam Stabilizers for Enhanced Oil Recovery

“…Surfactants are most commonly used as foaming agents in CO 2 foam injection. 26 A surfactant molecule has a hydrophobic tail and a hydrophilic head; therefore, a surfactant preferentially adsorbs on the gas−water interface, resulting in a reduction of the free energy at the interface due to a reduction in interfacial forces. Although surfactants are widely used as foaming agents in CO 2 foam flooding, surfactant-stabilized foam is difficult to maintain for a long time.…”

Supercritical CO2 Foam Stabilized by a Viscoelastic Surfactant in Fractured Porous Media: The Effect of Fracture Surface Roughness

“…Foam flooding, sometimes referred to as surfactant-assisted gas flooding, has drawn increasing attention in the oil and gas industry for enhanced oil recovery (EOR). − There are different gas types used for foam EOR, such as air, nitrogen, carbon dioxide (CO 2 ), and methane. Among them, CO 2 is the most interesting as it reutilizes the emitted CO 2 and could help alleviate the CO 2 emission to the environment.…”