This invention relates to a defoaming apparatus.
In various fields such as water treatment and some chemical industries there is a problem of disposing of foamed liquids. The problem is most severe, however, in the oil drilling industry where foams are commonly used when the geological strata support a relatively small pressure gradient and circulation of conventional drilling fluids would result in total loss of the fluids. Foaming agents are thus used to raise the liquids accumulated in the gas deposits. Likewise, the drilling, completion, and work-over of depleted oil reservoirs located in areas of great altitude or under a great depth of water need the use of fluids of specific weight ranging from 0.10 to 0.80 such as aerated muds or foams.
The foams are made from surface active materials and other additives such as stabilizers. They are propelled by pumps and gases under pressure and are immediately injected.
Back on the surface, these foams cannot be handled by the pumps. Consequently, in order to re-use the liquid and the gas, it is necessary to break the emulsion. Demulsifying products are costly and generally not very effective. Storage of the foams and the natural destruction thereof is a long, polluting, burdensome and uneconomical operation. In addition, when drilling in sedimentary strata, the gas used for the preparation of the foams is generally air. When the rock formation traversed contains signs of hydrocarbons, the air that is a constituent of the foam becomes charged with gaseous hydrocarbons and can become an explosive mixture. The risk of using an explosive mixture in the hole can be lessened by using methane for the preparation of the foam. But, above ground storage of the mixture is dangerous and, when the foam is destroyed, a gaseous mixture is released that could be explosive.