Minimization of Scale Deposits in Oil Wells by Placement of Phosphates in Producing Zones
- Aleck B. Featherston (Halliburton Oil Well Cementing Co.) | R. George Mirham (Halliburton Oil Well Cementing Co.) | A.B. Waters (Halliburton Oil Well Cementing Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- March 1959
- Document Type
- Journal Paper
- 29 - 32
- 1959. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 3 Production and Well Operations, 2.2.2 Perforating, 4.3.4 Scale, 2.4.3 Sand/Solids Control, 5.4.1 Waterflooding, 4.1.2 Separation and Treating, 5.2 Reservoir Fluid Dynamics
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Deposition of compounds such as calcium carbonate, calcium sulfate and barium sulfate in formation flow channels, on tubing, casing and producing equipment has continuously plagued the oil industry. Although polyphosphates have a long history in scale inhibition, only relatively recently have the extremely slow solubility di-metallic polyphosphates been injected into producing zones in conjunction with fracturing.
As a result of such treatments, scale deposition in the formation in addition to the wellbore and producing equipment has been checked in some cases for over a year. Characteristics to be considered when selecting a phosphate for this type treatment have been outlined with the effect each has on scale prevention and on length of time they will be effective.
Mineral deposition in formation flow channels, on tubing, casing and producing equipment has continuously plagued the oil industry. Compounds such as calcium carbonate, calcium sulfate and barium sulfate carried in the produced water may crystallize or precipitate as a result of a pressure drop, a temperature change or exceeding the solubility product. This scaling reduces and sometimes even stops oil production by plugging the formation, perforations or producing equipment.
Formation of scale on tubing and producing equipment has been recognized for many years. After extracting this equipment from the well, the deposits have been removed mechanically with scrapers and other such devices. Hydrochloric acid has been found effective when the plugging material is basically carbonate in nature.
As early as 1938 and 1939 Krynine and Yuster recognized that these scaling compounds frequently were deposited away from the wellbore in flow channels of waterflood wells. Acid, salts and phosphates were suggested as possible remedial treating chemicals. More recently work has been done which indicates water incompatible with the formation water sometimes can be used in water floods.
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