Schmoo and Emulsions – Challenges Influencing the Selection and Operation of Produced Water Treatment

Figure 2: Natural Organics and Hydrocarbon-related Compounds in Produced Water

TPH

Dissolved oil

Dispersed oil Aromatics

BTEX PAH NPD

Organic acids Fatty acids

Naphthenic acids

Aliphatics Linear

Branched Cyclic

Phenols Phenol Alkylated phenols Aromatics PAH

>C6 alkyl. phenols BTEX

Acids Fatty acids Naphthenic acids

Aliphatics Linear

Branched Cyclic

The hydrocarbon fractions included in the blue circles are the compounds typically included in the OSPAR oil-in-water monitoring method, which has been used here.

Figure 3: Oil Droplets in Different Produced Waters with Stable Emulsions

A: Stabilised oil droplets of 1–3µm.

B: Stabilised oil droplets <10µm.

C: Oil droplet in water with several small water droplets inside.

D: A solid particle coated with 1µm oil droplets.

E: Solid particles attached to oil droplets.

10

0 2 4 6 8

0,1110

Diameter (χ

m) Volume frequency distribution

G: Produced water with extremely stable emulsion (photo taken one month after sampling).

H: Oil droplet size distribution in the samples in Figure 3G.

Volume cumulative distribution

F: Solid particles in the interface of the solvent (pentane) and water phase after extracting the oil from the water samples in Figure 3G.

100

20 40 60 80

0 100

Whether an emulsion turns into an WiO emulsion or an OiW emulsion depends on the volume fraction of both phases and on the type of emulsifier. Generally, emulsifiers and emulsifying

124

particles tend to promote dispersion of the phase in which they do not dissolve very well. For example, proteins dissolve better in water than in oil and so tend to form OiW emulsions (that is, they

EXPLORATION & PRODUCTION – VOLUME 8 ISSUE 1

% volume frequency distribution

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