Overview of Subsea Processing (Oil and Gas Technology)

Oil/Gas Recovery originated from Land Drilling. With the increasing depletion of oil/gas reserves in areas which can be accessed via Land Rig, Offshore drilling springs up to address the large oil/gas reserves that are untapped under the seabed. With it, Offshore Rigs are developed. Some of the common Offshore Rigs includes Submersible Types (eg: Jack-Up Rig , Steel Jacket Rig and Gravity Based Rig), Semi-Submersible Type and Drilling Ships.

However, extensive boosting is required for oil/gas recovered to be transported to topside processing facilities on offshore platforms. Ultra-Deep Light Oil may not be recovered as these reservoir only has enough natural energy for the oil to flow up to the seabed but not all the way to the water surface to reach the topside processing facilities. Subsea processing enables ultra-deep oil to be recovered via subsea boosting whereby multiphase pumps are utilised to provide an artifical lift for the low energy oil.

Subsea processing presents significant potential for cost savings by moving some of the traditional topsides fluid processing to the seabed. Subsea separation and local re-injection of produced water and/or gas to the reservoir or to a dedicated disposal zone will allow flowlines and topside processing equipment to be used more efficiently. Subsea gas/liquid separation and liquid boosting can increase the production rate in low-energy reservoirs.

The main features of subsea processing:

Subsea bulk water removal, with re-injection or disposal
Subsea single-phase or multi-phase boosting of well fluids
Subsea sand and solids separation and sand handling system
Subsea gas/liquid separation and liquid boosting
Subsea gas treatment Subsea gas compression
Monitoring, control and instrumented safety systems


For over 20 years subsea processing has been poised as one of the most potentially promising technology developments in the offshore industry – and now, shifting factors within the sector over this period have finally begun to tip the balance in its favour.

In the early days, with deep water posing the biggest challenge, technological necessity and financial incentives formed the principal drivers.

Today, to meet the demands of deeper and more remote reservoirs, the emphasis is firmly on increased production and enhanced recovery.

While subsea developments have been made possible by technologies such as subsea trees, risers and umbilicals, subsea processing has been an elusive solution for many years. Whether describing subsea separation, re-injection or boosting, subsea processing has helped to revolutionize offshore developments worldwide.

A template is one of the first component to be inserted onto the seabed whereby all the various components such as Subsea Pumps, Separation units and Multiphase Metering will be bulit upon.

Various Sub-Components involved in Subsea Processing Template are as shown below in the pictorial diagram:

a. Solid Separator
b. Liquid Pump
c. Compressor (Subsea Compressors are still in the developmental stage)
d. Control Module
e. Water Injection Pump
f. Separator Tank
g. Control Valve

Benefits of Subsea Processing:

There are a number of reasons why operators may choose to install subsea processing equipment. First of all, most subsea processing will increase the recovery from the field, thus increasing profits. Additionally, by enhancing the efficiency of flowlines and risers, subsea processing contributes to flow management and assurance. Also, subsea processing enables development of challenging subsea fields, while reducing topside expenditures for equipment. Furthermore, subsea processing converts marginal fields into economically viable developments.

Offshore fields worldwide have encompassed subsea processing into their developments. Whether the fields are mature and the subsea processing equipment has been installed to increase diminishing production, or the fields incorporated subsea processing from the initial development to overcome deepwater or environmental challenges, the innovative subsea processing systems have enabled the fields to achieve higher rates of production.

With production equipment located on the seafloor rather than on a fixed or floating platform, subsea processing provides a less expensive solution for myriad offshore environments. Originally conceived as a way to overcome the challenges of extremely deepwater situations, subsea processing has become a viable solution for fields located in harsh conditions where processing equipment on the water's surface might be at risk. Additionally, subsea processing is an emergent application to increase production from mature or marginal fields.

Some of the links from the more reputable companies which deals with Subsea Processing are listed as below for your references:

http://www.fmctechnologies.com/

http://www.slb.com/

http://www.worldoil.com/

Video on the installation of Subsea Template:



Subsea Workings:

Simple Questions pertaining to Subsea Processing:

Questions to Ponder (Discuss on the Blog):


1. What do you understand about Subsea Processing?

2. What are the various technologies employed in Subsea Processing of Oil and Gas?

Term Paper (To be email to the author of the blog before 05 Dec 09, 2359hrs, xxxxx@hotmail.com):

Research on the first Subsea Processing (Clue: the first Subsea Processing took place in year 2007 at the North Sea)
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