ADAPTATION OF APPROVED LASER-INDUCED TIME-RESOLVED FLUORESCENCE SPECTROSCOPY IN OFFSHORE APPLICATIONS: EXPERIENCE OF 24 MONTHS MEASUREMENTS IN PRODUCED WATER

摘要

During the last three decades some oil producing companies have already installed in-line and on-line crude oil detection systems for monitoring the produced water discharges and for controlling the water handling systems on oil or gas producing facilities on- and offshore. However, very often these systems have not satisfied the requirements of the practical application and have been shutdown again. In general produced water processes are accepted to be sufficient, thus the concentrations of potentially harmful components are reduced to levels, which are agreeable for the surrounding environment. In the North Sea for example, the current protocol limits the content of discharged water to 40 mg/l Aliphatics averaged per month. Commonly, the remaining oil content is still carried out by taking samples in frequencies of e.g. every 48 hours, which are treated in a chemical laboratory extraction and a subsequent analysis. This becomes even more relevant, because the new standard laboratory method for all OSPAR OIC countries, valid from the beginning of 2007, is not ideally suited for an offshore application. In order to get a continuous overview of the separator process and the pollution of the environment by residual crude oil, an on-line monitoring system is required, which is specially adapted to the particular properties of produced water. For more than two years SYSTEKTUM GmbH has intensively been committed in cooperation with an oil producing company to optimize the approved laser-induced time-resolved fluorescence analysis system KONTAVISOR for the application in on-line produce water monitoring. Therefore, the instrument has been tested on an oil production platform in the North Sea, especially concerning the topics of calibration and correlation with regard to the laboratory analysis as well as eliminating the influence of scaling, fouling and oil contamination on the detection window of the optical measurement system. This paper will give a review of the fundamental physical and chemical properties and the results of the practical offshore experiences.