Produced Water Treatment System
Produced water is associated with exploration, production and processing of oil and gas.
Produced water may contain oil, solids (silt, clay, sand), gases (hydrogen sulphide, carbon dioxide, methane), dissolved iron, manganese and other metals, high content of dissolved salts and low or high pH, and low or high temperature.
The produced water treatment requirements are preliminary related to the type of disposal or re-use of the treated water and this includes disposal to the ocean or to deep injection wells, or to evaporation ponds or re-use for in-plant processes or combination of the above.
The diversity of the produced water quality in regard to the type and level of the impurities and the treated water quality requirements demands flexible and diverse treatment technologies. Also, a compact and efficient treatment system is desirable to meet site and economic requirements. Specific site conditions exist on off-shore platforms and existing on-shore plants which require produced water treatment upgrading or expansion.
A complete treatment is provided in a single vessel to separate oil, water, gas and solids which are usually contained in produced water from oil and gas production and processing operations.
The apparatus and process have flexible design to suit the produced water quality and treatment level required, and to provide an efficient, compact and complete treatment.
The apparatus and process can be operated under the atmospheric pressure or other pressure, higher or lower than the atmospheric pressure, and with or without a gas blanketing, to suit the sit conditions and to accomplish the required water treatment. The apparatus and process can operate as pressure or gravity flow system.
The treatment process includes demulsification, gravity separation, parallel plate separation, and diffused of induced gas or air flotation.
The system comprises several key components as follows:
- Primary conditioning compartment for adjustment of the inlet water pH, temperature and demulsification and flocculation of oil and suspended solids.
- Primary gravity separation compartment for separation of oil, gas and suspended solids from water.
- Enhanced gravity separation of oil, gas and suspended solids and water in a corrugated, parallel plate system.
- Polishing separation compartment for final separation of oil and gas from water by means of diffused gas flotation system.
- Treated water outlet compartment.
- Sludge removal system with automatic operation
- Oil removal system with automatic operation
- Gas removal system with automatic operation
- Instrumentation and controls.
A complete system can be provided in a single horizontal vessel or vertical vessel which may be preferred for off-shore platform or retrofit of an existing produced water treatment plant.
Additional treatment units in two vertical vessels can be provided for oxidation/coagulation/flocculation (in one vessel) and one or two stage filtration (in one vessel) for a high quality treatment to meet stringent environmental or process re-use requirements.
Examples of the system: