Substantial foam formation was being experienced by two operators in several heavy oil leases in Northern Alberta. This 10 – 12 API crude had a large foaming potential and unique foam formation mechanism. Crude oil passed from the wellhead, via a short flowline to a pair of hydrostatically balanced and heated storage tanks. The storage tanks heated the crude oil from approximately 50°C to 85°C and in doing so, caused gas breakout and degassing which resulted in the formation of a thick, persistent foam in the top of the tanks. The foam would enter the transportation trucks and end up at the local battery and create carry over and separation problems in the process systems.

Silicone antifoam products were not acceptable due to both their poor environmental profile and also the influence these large molecules had at the refinery where the crude oil was shipped for (predominantly) asphalt manufacture.

A wide range of chemistries were tested including phosphate based products, ethoxylated and propoxylated esters, polyethylene glycol esters and oleates, alcohols, fatty alcohols and ethoxylated and propoxylated alcohols. One of the major challenges detailed in this paper is that all products had to be freeze protected to −40°C. This was significant due to many anti-freeze chemicals affect the efficacy of antifoam chemicals.

This paper details evolution of testing leading to the field application of this combined defoamer / antifoam chemistry. Initial laboratory screening is included which describes a unique laboratory test method designed to mimic more accurately the foam formation environment in the field. The paper goes onto illustrate the field trial evaluation as well as the case histories of full field implementation of the highest efficacy products.

You can access this article if you purchase or spend a download.