October 30, 2024

Universal downhole dosing unit – a universal assistant in the fight against salts and corrosion

Damage to submersible pump installations due to salt deposits and the carryover of insoluble solid particles from the reservoir remains one of the main factors complicating oil production. Novomet offers a comprehensive solution to this problem – the use of salt deposition inhibitors, filters (previously discussed here/link), and separators, as well as various design implementations.

"The formation of salts in the well occurs due to the supersaturation of water with poorly soluble salts when there are changes in temperature, pressure, pH levels, gas release, or mixing incompatible liquids. Salt is dangerous because it precipitates on equipment, mainly on pumps," explains Novomet process engineer Dmitry Savakov. "To protect against this, oil workers have several methods – physical, chemical, and technological. Today, the most effective method is chemical technology – the use of salt deposition inhibitors. They are introduced into the reservoir fluid and suppress the growth of salt and corrosion crystals. The best way to deliver them to the well is through containers installed beneath the submersible electric motor. Their advantages lie in the simplicity and convenience of installation and low operating costs."

The universal downhole dosing unit consists of a cylindrical body containing the inhibitor and a dispenser that controls the uniform flow of the mixture for at least a year. The technology operates without additional equipment and without human control, which enhances the efficiency of servicing wells in hard-to-reach areas. The location of the container at the bottom of the installation protects not only the pump but also all equipment, including safeguarding the motor from overheating.

A fundamental feature and advantage of the universal downhole dosing unit design is the placement of the dispenser on the container lid. This allows it to be used in simultaneous-separate operation when, due to the presence of a packer, it is not possible to dose the inhibitor from the surface.

The container is called universal because it can work with both solid and liquid fillings, as well as with chemistry against salt deposition and corrosion. Inhibitors in capsule form have become particularly widespread since their active base dissolves gradually rather than immediately. The design of the container for encapsulated inhibitors was proposed to reduce reagent consumption at the initial stage and to ensure a long-term stable supply of inhibitor into the reservoir fluid. This technology has undergone pilot industrial testing and has proven successful in operation with submersible electric pumps (ESP) at fields, with operational durations reaching up to 600 days or more. It can also be used in horizontal wells.

Thus, dosing units are installed in a single operation with the ESP, making them one of the most effective and economical solutions for preventing salt deposition and ensuring longer operation in the well.