Page 40: of Offshore Engineer Magazine (Aug/Sep 2016)

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SUBSEA

Enhancing

Back deck of an

Oceaneering vessel.

Images from Oceaneering production

International.

contribute to deposits. The ? rst step to can spend as much as US$20 million on

Oceaneering’s Justin Pizzitola restoring production is for oil company a rig-based subsea well stimulation.

discusses the use of an open production engineers to analyze the

Rigless intervention produced ? uids to determine the cause water dual coiled riser based of the blockage and to select the ap- An alternative method, developed system for rigless stimulation.

propriate treatment chemicals. During by Oceaneering International, uses a this analysis, the engineers also review multiple-purpose service vessel (MSV) or more than two decades, the reservoir characteristics to determine to safely and ef? ciently perform well complexity of the deepwater the formation’s injectivity and optimum stimulations without a drilling rig or

F environment has become more pumping rates. riser. The MSV carries two work-class challenging, driving the need for more

ROVs, and has a crane for lowering

High-cost rig-based intervention alternative solutions and advancements equipment with varying tonnage to

Until 2009, the only method of perform- the sea ? oor. Equipment includes one in technology. From new wells that come ing subsea stimulations was to deploy a or two open water dual coiled tubing online to aging wells, well intervention mobile drilling rig and a high pressure riser units, ? ying leads, high pressure is required to stimulate ? ow and maxi- pumping vessel. In the current environ- pumps and associated high pressure mize production. An alternative, rigless ment of low oil and gas prices, ? oat- piping, and an innovative well stimula- stimulation method has been developed ing rigs may be readily available, but tion tool. The MSV can carry up to 5000 and used successfully on dozens of wells increased drilling activity will likely bbl of treatment chemicals. If a higher in the Gulf of Mexico and West Africa. make scheduling of rigs much more chemical volume is required, a second

Production enhancement from this alter- problematic. Even at today’s depressed pumping vessel can be employed to native method yields results comparable day rates, contracting a rig can still avoid additional trips to shore. This to those achieved using rig-based methods be an expensive proposition. Once on method allows for rig-up and testing to while reducing costs by as much as 50%.

location, preparations for the stimula- be completed in as little as two days so

Aging wells need rejuvenation tion job – including setting a blowout stimulation can begin quickly.

After a subsea well is online for several preventer and drilling riser to connect The well stimulation tool is the main years, its production can be impaired the subsea wellhead to the surface – can interface between the topside and the by sand migration and/or by deposition take a week or longer. Large crews for well tree. To assure safe operation, it of wax, paraf? n, asphaltenes and scale. the rig, pumping vessel, and asset sup- provides a double barrier for well con-

Increased water cut in older wells can port teams, add to the cost. Operators trol, and includes two “fail-close” valves,

August 2016 | OE oedigital.com 42 042_OE0816_Subsea3-Oceaneering.indd 42 7/22/16 11:59 PM