Currently the field architecture for most deepwater developments has been dictated by flow assurance constraints due to a reliance on conventional dual flowline loops with riser base gas lifting. Subsea boosting and separation technology will help expand these traditional boundaries and hence facilitate the operation of longer, deeper pipelines transporting fluids with lower temperatures and pressures.
Providing power to remote subsea equipment, which consume power measured in mega watts, will result in power distribution becoming a new driver for field architecture. High voltages will not necessarily be compatible with current power and control technology.
Contractors will therefore have to engineer and deploy large subsea units and integrated power and control umbilicals to match the new field architecture. The reliability of the power distribution system takes on a greater importance. Simply put, loss of electrical power will equal loss of production. How contractors adapt and qualify new technology during the design and installation phases of a project will be a key to its success.
A case study will be presented for boosting a remote deepwater oil field comparing the flowline and umbilical sizes and power requirements for different field layout options. The paper will highlight the implications that the power distribution systems have on the optimization of the field architecture.
The start of the twenty first century saw the emergence of a number of large deepwater fields in West Africa, the Gulf of Mexico and South America. The technical risks associated with these developments were numerous but ultimately not insurmountable with flow assurance emerging as one of the main drivers for selection of the field architecture.
Flow assurance is a relatively new engineering discipline to the oil and gas industry, encompassing a broad range of engineering and scientific disciplines. Flow assurance gained particular importance for deepwater fields due the increased energy losses occurring in the riser. Deepwater reservoirs can be characterized with relatively low reservoir pressures and temperatures with viscous fluids with high wax appearance temperatures. The static head losses over 1000 to 2000 m are high and represent a high percentage of the total hydraulic losses and there is an accompanying temperature reduction due to the Joule-Thomson and loss of potential energy effects.
