HSE Horizons - This is a condensed version of paper SPE 73853, which was presented at the SPE International Conference on Health, Safety, and Environment in Oil and Gas E&P held in Kuala Lumpur, Malaysia, 20-22 March 2002.

TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract Produced Water Volumes

Summary Chemical enhanced oil recovery (EOR), including polymer and surfactant-based processes, is a method that operators consider to maximize oil recovery from onshore and offshore reservoirs. Because of the logistical, operational, and environmental differences and the footprint and required weight needed for additional injection and production equipment, offshore chemical EOR processes are challenged by greater complexity and costs as compared with onshore applications of the same technologies. Chemical EOR commonly requires large volumes of injection chemicals, as well as demulsifiers to break produced-water/oil emulsions and inhibitors to control scale, resulting in high shipment and storage costs. The use of seawater and/or produced water for injection of the chemicals into offshore fields mandates stringent processing of both streams to allow optimal injectivity, sweep efficiency, and chemical effectiveness in the reservoir. Offshore production of saleable oil and clean water requires space- and weight-efficient oil/water-separation equipment. Currently, conventional methods for processing produced fluids fall short in both efficiency and compactness. High offshore drilling costs lead to relatively large well spacing and more difficulty in monitoring the EOR subsurface process, and lead to restrictions on the number of disposal wells. Finally, environmental restrictions limit the overboarding of toxic or poorly biodegradable EOR chemicals. The industry is currently investigating the limiting factors pertinent to offshore chemical EOR. As a result of these efforts, new enabling chemistries and technologies are being examined for improving surface operations to allow cost-effective offshore chemical EOR to be performed in an environmentally sound and safe manner. Some of these recent chemical- and fluids-processing developments are described in this paper. Subsurface challenges to implementing offshore chemical EOR are also highlighted, along with potential solutions.

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Recently, the rotational particle separator (RPS) was introduced as a new technique for separating solid and/or liquid particles of 0.1 lm and larger from gases. In this patented technique the principles of centrifugation are exploited to enhance separation of small-sized phases and particulate matter of density different from the carrier fluid. Practical designs of the RPS available in the market include equipment for purifying gases of industrial processes and portable air cleaners for domestic appliances. New developments are made in the area of the offshore industry. It concerns the separation of oil droplets from water and the separation of condensate, oil, and sand from natural gas. A particular feature of both designs is that the filter element is freely mounted in bearings and rotates, without the need of a motor, by introducing a swirl in the fluid flowing towards the filter element. The design is particularly suited for operation under high pressures as the rotating filter element is fully contained within a cylindrical pipe. The shaft does not pin through the external wall, so no sealing is required. Based on known RPS design principles and fluid flow relations an oil-water separator is designed and tested.