METHOD TO REVEAL BEHIND-THE-CASING FLOWS, WHICH CAUSE GYPSUM DEPOSITS Russian patent published in 2006 - IPC E21B47/10 

FIELD: oil and gas well construction and operation, particularly to prevent gypsum-containing salt deposition on equipment for raw oil production, refinery and transportation.

SUBSTANCE: method involves creating control composition background and detecting control composition presence. In the case of oil field development with the use of fresh and waste water to maintain formation pressure laboratory researches are carried out to determine background sulfate-ion content in mineralized water saturated with gypsum. Water may have any mineral content. Then check sample of liquid to be produced is taken and produced water is separated from oil. Total mineral and sulfate-ion content is determined in taken samples. Minerals and sulfate-ions are used as control composition. Sulfate-ion content is compared with background content and behind-the-casing flow presence can be inferred by abnormal increase of sulfate-ion content.

EFFECT: reduced costs and extended technological capabilities, elimination of expensive instrumental researches due to usage of control compositions based on sulfate-ion content in produced water, possibility to avoid the need of producing well shutdown due to sample taking at well head.

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