Abstract: A system, including: a subsea separation system that separates sales and non-sales fluids, wherein the subsea separation system includes a fluid polishing system; a seal-less pump that boosts production fluid pressure; and a water quality monitoring system, including an oil-in-water sensor and a solids-in-water sensor, that monitors a fluid discharged from the subsea separation system.

Abstract: A system, including: a subsea separation system that separates sales and non-sales fluids, wherein the subsea separation system includes a fluid polishing system; a seal-less pump that boosts production fluid pressure; and a water quality monitoring system, including an oil-in-water sensor and a solids-in-water sensor, that monitors a fluid discharged from the subsea separation system.

Abstract: A subsea reservoir pressure maintenance system, including: a subsea chemical storage unit; a seawater intake and treatment system that takes in seawater and chemically treats the seawater with a chemical stored in the subsea storage unit, wherein a first subsea seal-less pump transfers the chemical from the subsea chemical storage unit to the seawater intake and treatment system; a second seal-less subsea pump that boosts pressure of the chemically treated seawater received from the seawater intake and treatment system; and a water injection manifold that receives the chemically treated seawater at the boosted pressure and injects the chemically treated seawater into a seabed.

Abstract: An oil-in-water monitoring (OIWM) system for monitoring an oil-in-water concentration of treated water in a subsea processing system. The system includes a first OIWM portion including a separation component configured to separate the treated water stream into a separated oil portion and a separated water portion which has a plenum including the separated oil portion and the separated water portion. A separation component instrument is operatively coupled to the plenum. The system also includes at least two of: an oil line instrument operatively coupled to an oil line, a water line instrument operatively coupled to a water line, and an inlet line instrument operatively coupled to the inlet line. A computational device is configured to output an oil-in-water concentration of the inlet treated water stream using the parameters measured by the separation component instrument and at least two of the other instruments. Methods using such systems are also disclosed.