With potential increase in water injection requirement, increase in oil production rate and the unavoidable increase in water production, an improvement in the chemical treatment programmes was deemed to be necessary in the mid eighties. As a result, an assessment of the chemical treatment programmes philosophy was carried out in the Statfjord field. The assessment programme philosophy covered different aspects of all chemicals used for the water injection systems, process systems as well as utility process related facilities, such as, ballast water systems, heating and cooling systems and fire water systems on the three Statfjord platforms. The assessment programme was intended to improve the methods used for selecting chemicals for the different systems and improve the application and the daily follow up of the chemicals offshore. Consequently, a better control on the consumption of the chemicals in the field can be achieved, as well as reduce the environmental impact and risk of the use and discharge of production chemicals in the North Sea.
The objectives were achieved by adapting a systematic approach in the selection and application of chemicals. The issues covered in these objectives included:
Clearer definition of individual problems in the systems
Select suitable simplified methods for testing new chemicals, either onshore or offshore
System parameters optimisation included in the testing programme for chemicals
Chemicals characteristics and partitioning in the individual systems
The toxicity of chemicals and biodegradability
The handling aspects of chemicals by offshore personnel
Improvements and upgrading of the chemical injection facilities
Establish operation procedures in order to implement and follow up the required treatments
Improve the chemical injection facilities on the platforms
In addition, a training programme was introduced for operation personnel, in order to improve the level of knowledge as well as understanding of chemical treatment requirements, and the importance of these programmes in maintaining stable operation and in reducing fluid handling related problems.
Having completed the assessment and the implementation of the new chemical treatment programme philosophy by the late eighties, a new chemical treatment and management system was established on Statfjord platforms. The outcome of such an approach was, more effective treatment, as well as reduced cost and quantity of chemicals used per volume of oil produced, treated produced water and treated injected water.
With the increased environmental awareness, the new procedures gave a better and an instantaneous view on the level of used and discharged chemicals. Such data are required for regular reporting to the environmental authorities.
The experience gained over the past few years has been also used in improving the design of the required chemical injection facilities on newly developed platforms, as well as chemical treatment programmes on newly developed fields.