Satellite Field Development: A Review of Problems Associated With Transport of Multiphase Well Products and Prediction of Their Behaviour
Authors: Sarshar M.M. 
Published: October 2008

The development of many satellite fields relies on transport of well products to a nearby host platform. To achieve economic design and reliable operation, clear understanding of multiphase flow phenomenon is necessary. In this paper some of the key features of multiphase flow, method of analysis and problems associated with understanding and predicting its behaviour are discussed. Examples are given of the research undertaken by BHR Group to overcome some of these problems. Recommendations are made to identify the limitations and the level of the accuracy of existing software models. The need for extensive research work to quantify the effect and the role of key parameters involved in multiphase flow is emphasised.

1. INTRODUCITON

The most economical method for the development of majority of satellite fields is direct transport of well products to a nearby host platform or production facility. Offshore satellite marginal fields have limited recoverable reserves which often fall well below 100 million barrels of oil and cannot support the high capital cost of conventional fixed or floating platforms. The economic constraints are further aggravated by some of the following factors:Fragmented reservoirs, requiring a large number of wells in comparison with total production achievable.Location in deep waters, requiring diverless techniques for installation and maintenance.Rapid pressure decline, requiring water injection and gas lift to maintain production.Long distance for transport of well products to a host platform.Sand production.Chemical injection to minimise the effect of corrosion, wax and scale formation and to prevent the formation of hydrates.

These problems result in an increase in the complexity, the capital cost and the operation costs of the production systems associated with these fields.

Whatever concept is selected for the subsea production system, successful and economical transport of well products are the main technical and economical challenges.

2. OPTIONS FOR SUBSEA PRODUCITON

For a multi-well satellite field, the most economical methods of developing the field is to manifold and transport the products along a single line. This technique has in fact been adopted quite successfully in the past. A good example is the recent development of Strathspey, Lyell and Staffa fields in the North Sea, all of which use the Ninian field as the host platform. The main features of these fields are their relative short distance, below ten miles in this case, from the host platform and little difference in water depth between the satellite fields and the main platform. The unique achievement in the development of these fields has been the involvement of three separate operators, with the main platform facilities being operated by the fourth operator (Chevron). (Ref 1).

It is also worth noting that in this example all process operations are completely separate on the host platform mainly because of the absence of suitable multiphase flowmeters which, if available, would have allowed accurate metering of flow within 2% to 5% accuracy from each field. This would have enabled the commingling of the multiphase products upstream of the process system with considerable savings in the capital costs.