Effect of Surfactant Concentration, Water Treatment Chemicals, Fatty Acids and Alcohols on Foam Behavior in Porous Media and in Bulk

Effect of Surfactant Concentration, Water Treatment Chemicals, Fatty Acids and Alcohols on Foam Behavior in Porous Media and in Bulk

Laskaris, G.

Rossen, W.R. (mentor)
Vincent-Bonnieu, S.Y.F. (mentor)
Jones, S.A. (mentor)

Civil Engineering and Geosciences

Section Petroleum Engineering

2015-12-18

Foams find many applications in the oil industry with their uses ranging from fracturing stimulation treatments to enhanced oil recovery processes. Many of these applications concern the reduction of injected gas mobility which can be induced by a strong foam. However, foam behavior inside a porous medium is complex and a fully predictive model has not been developed to date. This study aims to contribute to the understanding of how the variation of parameters such as surfactant concentration or the presence of certain chemicals, either injected as foam boosters or as part of the water treatment process, affect foam behavior in porous media. For that reason, four series of coreflood experiments were conducted by using pencil-sized cores. In addition, pH and surface tension measurements were conducted in order to facilitate the interpretation of the coreflood results. Lastly, bulk foam experiments were also carried out in order to assess whether easily obtained bulk foam behavior parameters can correlate to foam behavior in porous media. The first experimental series of this study examined the effect of surfactant concentration on foam behavior in porous media, with the ultimate aim to capture the surfactant concentration effect in a local equilibrium (L.E.) model. Given that foams in field applications and in laboratory coreflood experiments are created with different surfactant concentrations it is important to understand how foam performance varies with concentration. According to the experimental results, both the foam apparent viscosity and the limiting capillary pressure increase for increasing surfactant concentration. The L.E. model at its current state was not able to capture this effect, as observed during the modeling part of this study. More specifically, there was a vast deviation in the matching of the low surfactant concentration coreflood results with the F1 function which describes the effect of surfactant concentration in the current L.E. models. The second experimental series conducted in this study examined the effect of straight chain primary alcohols of six different carbon chain lengths on foam behavior in porous media, with the potential to identify foam booster chemicals for field applications. As observed in the experimental results of this series, the addition of very small amounts of four of the alcohols can increase the foam strength in the core considerably. Interestingly, the bulk foam behavior for as a function of alcohol carbon chain length varied with an opposite trend compared to the foam behavior in the core. Therefore, 1-dodecanol created the least strong foam in the core among the alcohols examined, while in bulk it resulted to the most volumetrically stable foam. The third experimental series assessed the foam boosting potential of three fatty acids. All the fatty acids examined at low concentrations increased the foam strength in the porous medium and the bulk foam stability. However, at higher concentrations this effect was inversed and the fatty acid additive reduced the foam strength in the core considerably. An interest aspect of foam behavior in porous media was also examined in this experimental series that being the effect of the stearic acid on the non-Newtonian foam flow in the core. Interestingly, for low total velocities the flow behavior in the low quality regime was found to be shear thickening, contradicting the theory. Finally, the fourth experimental series examined the effect of three representative water treatment chemicals, i.e. one oxygen scavenger, one biocide and one antifoam, on foam strength in porous media. These chemicals are added to the injection water according to the typical water treatment procedure in fields and thus they could potentially affect foam performance when they reach the rock formation. Interestingly, the addition of each of these three water treatment chemicals had a beneficiary effect on foam strength in the core. In the case of the antifoam formulation, a threshold concentration was observed, such that for antifoam concentrations below 10 ppm the antifoam increased the foam strength in the core.

foam in porous media
foam booster
water treatment chemicals
oxygen scavenger
antifoam
biocide
bulk foam
foam stability
foam strength
fatty acid
alcohol

http://resolver.tudelft.nl/uuid:56a43b7d-2cd6-41b2-9958-88cc53f82f71

Student theses

master thesis

(c) 2015 Laskaris, G.