METHOD OF EXTRACTING OIL, WHICH INCLUDES IMPROVED SOFTENING OF FORMATION WATER Russian patent published in 2019 - IPC E21B43/24 E21B43/40 C02F1/66 C02F5/02 

FIELD: oil industry.

SUBSTANCE: invention relates to treatment of formation water occurring as a result of oil extraction process and its use for production of steam for extraction of oil. Method of extracting oil from oil-bearing reservoir comprises: a. extraction of oil/water mixture from oil-bearing formation; b. separation of oil from oil/water mixture for production of oil and formation water of hardness; sec. directing formation water to a softening unit for softening formation water; d. directing formation water from a softener into an evaporator having heat transfer tubes, and evaporation of at least a portion of formation water to form concentrated brine and steam; e. condensation of steam to form a distillate; f. directing the distillate to the steam generator and heating the distillate in the steam generator in order to produce steam; g. introduction of steam produced by steam generator into injection well. Stage c comprises increasing the pH of the formation water in the softening unit and softening the formation water in the softening unit and depositing solid compounds from the formation water. Softening of formation water in the softening unit and deposition of solid compounds in the softening unit includes the following: I. mixing alkali with formation water in a softening unit; II. improvement of formation water softening due to direction of at least part of concentrated brine produced by the evaporator into the softening and mixing unit of concentrated brine with formation water and alkali in the softening unit, which promotes increase of the formation water pH in the softening unit. Stage d includes flow of precipitated solid compounds through heat transfer tubes of evaporator without considerable formation of deposition on them.

EFFECT: technical result is improvement of softening in order to remove stiffness.

3 cl, 1 dwg