EVALUATION OF HYDROCYCLONE PERFORMANCE FOR NORTH SEA PRODUCED WATER

摘要

The performance of liquid-liquid hydrocyclones was evaluated for handling the produced water at the Texaco Tartan "A" Platform in the North Sea. These hydrocyclones were handling effluent water from the high and low pressure production separators at the Platform. The purpose of the subject hydrocyclones is to remove oil from water in order to meet the regulatory discharge standard. The performance of a liquid-liquid hydrocyclone is determined by their ability to remove particles of a certain size as guided by Stokes Law. Our focus was to find the most reliable way to accomplish the measurement of oil droplet size distribution to obtain a measure of the hydrocyclone performance. Generally speaking, people tends to use a particle size analyzer for such measurements. Unfortunately, most of these analyzers can not distinguish oil from solid particles. Without special procedures, the result is an erroneous conclusion showing more oil with a skewed particle size distribution than is actually present in the sample. We have used the microscope at locations where solid particles were great enough to interfere with the results of the instrument measurement. Although the microscopic measurement is tedious, it can distinct oil from solid particles and obtain a reliable result. Moreover, the water samples were collected at the inlet and outlet of the hydrocyclones with special designed shear-free samplers. Additionally, the oil droplets in the water samples were immediately "captured" by a polymeric solution, so that they could not separate from water or coalesce during the transport of samples to the measuring location. Using the above methods, our on-site measurements indicated that these hydrocyclones performed as they are designed. For the low pressure separator, the oil droplet sizes were relatively small, the hydrocyclones could not remove enough small oil droplets. Deoiler chemicals were used upstream of the system to improve the oil removal from water. The above method has also been used for predicting the potential hydrocyclone performance at new locations.