Phosphonates - A Chemical Answer to Oilfield Water Problems
Authors: Ralston P.H. 
Published: December 2007

This paper was prepared for the Oilfield Chemistry Symposium of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., May 24–25, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Failure to treat the aqueous phase during oil recovery can markedly increase operator costs. This connate brine or secondary-recovery flood water can corrode pumps and flow lines, plug filters and scale the formation surfaces plug filters and scale the formation surfaces and the well-bore areas.

A family of organs-phosphorus compounds— the aminomethylenephosphonates and the disphosphates have been found particularly useful in controlling these problems. These phosphonates alone or in combination with zinc phosphonates alone or in combination with zinc ion effectively control oxygen corrosion in secondary recovery systems. Threshold concentrations (0.1 - 25 mg/1) of the phosphonates also control the deposition of calcium carbonate, calcium sulfate and barium sulfate in primary or secondary oil recovery systems. In addition, these phosphonates have the ability to stabilize dissolved iron and disperse water-borne solids at low milligrams per liter treatment rates.

The chemical and physical properties of the phosphonates observed in the laboratory and field demonstrate their versatility as a chemical answer to aqueous oilfield problems related to corrosion, scale and deposits.

Water and oil may not mix but they necessarily coexist. In primary crude oil recovery operations and in secondary water flooding applications, oil and water flow together in the same formation and in the same tubing. Since the recovery of the crude at a profit is the primary aim, the aqueous phase has received secondary attention. But this situation is unfortunate, for the absence of water treatment or the inadequate chemical conditioning of water can reduce oil recovery rates, increase production costs or decrease the life of production costs or decrease the life of the producing well. Correct conditioning of water in the oil patch can protect the oil producing formation and the operator's high investment in drilling, pumping and distributing equipment. When water related corrosion, scale and dissolved iron are controlled in produced water and injection water, the aqueous phase becomes coequal with oil in an unfortunate marriage.

However, this water phase does not consist of pure H2O.