Marine Technology Reporter Blogs - separation

Geopolitical location, an abundance of fish and huge O&G reservoirs make the South China Sea (SCS) particularly attractive to the countries that all lay claim to parts of it, such as China, Taiwan, the Philippines, Malaysia, Brunei, Vietnam, Indonesia, Singapore, Thailand and Cambodia. While the Chinese National Offshore Oil Company (CNOOC) estimates the SCS holds around 125 billion barrels of oil and 500 trillion cubic feet of natural gas in uncorked reserves, the U.S. Energy Information Administration (EIA) estimates the SCS contains only approximately 11 billion barrels of oil and 190 trillion cubic feet of natural gas in proven and probable reserves, although the EIA admits this figure could increase pending geological surveys of peripheral locations.

Petrobras has set plans to spend $5.6 billion through 2016 to increase output at the Campos Basin mature fields which have had decreased outputs for some time. Most post salt fields at the Campos Basin have been in production since the 1980s, some of which have been major producers. A steep decline in production began around 2009, not only due to the aging fields having low reserves but also because of lack of investments in operational resources and equipment for the older fields. The national operator will invest $1 billion in new money and spend $4.6 billion in operating costs to boost efficiency in the offshore Campos Basin operating unit to historic levels of about 90%, up from 72% in the first quarter of 2012.

The advent of reliable subsea processing has taken a considerable time to develop. For a few years now, it has been looked at as a vital solution for deepwater O&G development. Subsea processing technology was first developed to overcome challenges posed by extremely deep wells but in time it has become a proven solution in mature fields by decreasing the amount of equipment on the surface, therefore lowering operational costs and of course by boost diminishing production from mature wells, normally through re-injection of fluids, such as water, into the wells to increase the pressure inside the well. It is also an important solution in locations where harsh surface weather conditions make it extremely risky to have an anchored production plant.

The Marlim Field in the Campos Basin is the host for the world´s first operational system for deepwater subsea separation of heavy oil and water including the vital water reinjection to boost production in this mature Brazilian oil field and may be a key factor in expanding the production life of other mature fields in Brazil. Marlim is located in the north-eastern part of the Campos Basin, about 110km offshore of Rio de Janeiro, in water depths ranging from 650m to 2,600m (2,100 to 8,500ft). It has some 102 production wells, 50 injection well and 8 floating production units (FPU), devoted to the extraction of O&G. Marlim as a mature field approaching 20 years in operation…

New discoveries and the development of deepwater and ultra-deepwater pre-salt increases the demand for subsea equipment and service providers, attracting various international and local companies to compete for subsea contracts for the Brazilian offshore.The deepwater scene is in full swing in Brazil, with major projects being developed by various operators and national operator Petrobras. All these projects require a multitude of subsea equipment and subsea services, which accounted for a steady growth in subsea equipment and service providers from around the world setting shop in Brazil. Companies that have a history of quality equipment and services usually have an advantage when disputing these contracts, but the final product and services price is also a major issue.

Subsea gas-liquid separation coupled with liquid boosting can be an effective means of oil reservoir exploitation. Despite advances, multiphase pumping technology remains limited in its capabilities. Dynamic (centrifugal and helico-axial) pumps function with reasonable efficiency for single-phase, low-viscosity liquids. However, they become very inefficient when a high-viscosity liquid is combined with high percentages of free gas. While use of multiphase pumps is in many instances an effective solution, special consideration must be taken when challenging conditions exist such as are found in deeper water or with long tieback distances, or when heavy-oil production is involved. More effective oil reservoir exploitation can be achieved using subsea separation coupled with liquid boosting.