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IOR 2019 – 20th European Symposium on Improved Oil Recovery
- Conference date: April 8-11, 2019
- Location: Pau, France
- Published: 08 April 2019
121 - 122 of 122 results
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Insights into Effects of Surfactant Concentration on Foam Behavior in Porous Media
Authors S. Kahrobaei and R. FarajzadehSummaryA potential solution to mitigate the adverse effects of viscous fingering, gravity override, and reservoir heterogeneity on the efficiency of gas injection in porous media is to inject the gas with a solution containing surface-active agents such as surfactants or nanoparticles. The efficiency of these processes largely depends on the generation and stability of the lamellae residing in the pores, both of which are influenced by the physicochemical properties of the rock and surfactant solution. In this study, the effect of surfactant concentration on the transient and steady-state foam behavior in porous media was investigated. Several core flood experiments were conducted, in which the nitrogen gas and surfactant solutions with different concentrations were simultaneously injected into a Bentheimer sandstone core. Moreover, the ability of the current foam models in simulating the effect of surfactant concentration was examined and modifications were suggested accordingly. For the cases investigated and under our experimental conditions, the following conclusions are made:
- Strong foams can be generated with a very low surfactant concentration in the low-quality regime, albeit with a very slow generation rate.
- Surfactant concentration has a significant influence on the transient foam behavior or foam generation. The rate of foam generation increases with the increase of the surfactant concentration.
- The transition from coarse to strong foam occurs earlier as the surfactant concentration increases.
- Surfactant concentration does not impact the steady-state behavior of foam in the low-quality regime.
- In the high-quality regime, the foam strength increases with increasing surfactant concentration. This is attributed to the influence of the limiting capillary on foam stability in this regime, whose value increases with the increase in surfactant concentration.
- The current formulation of the steady-state implicit-textured foam models is unable to model the effect of the surfactant concentration, because the current model scales both high- and low-quality regimes with the surfactant concentration.
The only surfactant dependent parameter in IT foam models is the limiting water saturation or the fmdry parameter. Therefore, the effect of the surfactant concentration can be reflected solely by the fmdry parameter and there is no need for a separate surfactant-concentration function
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Single Well Campain Exposes Substantial Opportunity in Barrancas High-Temperature High-Salinity Formation
Authors R.A. Lucero, G.F. Villarroel, E. Lenzano, V.C. Consoli and J.E. JuriSummaryChemical EOR is at the edge for high temperature and high salinity, reservoirs. Further challenges appear in these reservoirs such as mixed-wettability, clays with a high content of divalent ions, mid to low permeability, injectivity problems for surfactant and polymers. Nevertheless billions of barrel remain in Barrancas Formation at 98–105 C and 65–85 g/L as TDS (2.2g/L to 3 g/L divalent ions) with some anihidrate content. The usual approach for this type of reservoirs has been to develop alkali-surfactant-polymer formulation with softened water and standard HPAM. However, water desalinisation-softening is very challenging to implement because of economics, environmental and logistic restriction to desalinisation-softening waste disposal. Instead, we targeted the actual water conditions to design the surfactant-polymer cocktail. We collected fluid samples from the six reservoirs producing from Barrancas Formation, and we obtained the equivalent alkane carbon number for each crude oil. An automated robotic platform assisted the formulation screening process. We coreflood outcrop samples to test surfactant polymer performance and multiple samples from three of the six reservoirs restoring wettability. Then, we implemented three single well tracer test with different formulations in the three major fields of Barrancas Formation. We used a new generation of traces manufactured by Restrack which allowed us to obtain a residual oil saturation distribution along the radial direction pre- and post-surfactant polymer injection. Knowing the saturation distribution along the radial direction can assist in the determining the interplay between adsorption, dispersivity, downhole temperature variation and optimal conditions of the surfactant cocktail. The three single wells also seemed to confirm mixed-wet wettability. Because of the residual oil saturation before surfactant-polymer was the equal independent permeability and reservoir quality/capillary desaturation curve. The three single wells recovered from 40% to 18% of the residual oil saturation based on an average volume calculation using the conventional tracers.
Further calculations using new generation tracers indicate that the recovery was affected by suboptimal conditions that vary along the radial direction, operative conditions during production phase that smooth-out traditional tracers. The data obtained by the new generation tracers indicated that the recovery could be locally higher than the conventional tracers calculations.
Adsorption in the single well tracer test was significantly lower than in corefloods (10 times smaller). Dispersivity indicated that for upscaling the surfactant performance to model interwell pilot a cell's size below 1 meter was needed. Alternating surfactant and polymer could improve injectivity of sulfonated polymer rather than simultaneous injection.
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