This paper introduces and demonstrates a simplified hydraulic design methodology of an oil water pipe inline separator for subsea deployment in a hydrocarbon production system. The oilwater pipe separator consists of an inclined tube section with evenly spaced tapping points at the bottom from where water rich streams are withdrawn.
Two main steps of the hydraulic design process are discussed in detail and demonstrated using numerical modeling, synthetic and literature data. The steps are: 1) assessing the potential production gain of installing the inline separator in a subsea production system and identifying the required separator performance and 2) Quantifying the separation performance of a single tapping and predicting the separation performance of a group of tapping points.
The results show that the proposed methodology can be successfully used to: Evaluate the potential gain in oil production when installing a subsea oilwater separator; Obtain a rough approximation of the required performance of the separator (required drained water flow rate and associated oil content) to achieve a given desired production increase; and estimate the approximate number of tapping points required and their operating conditions.
The concepts and methodology discussed in the present work can be easily generalized to other subsea separation techniques. They allow to determine the feasibility of installing a separator on a subsea production system and a concept to measure and predict the performance of separation techniques based on tapping.
