Safety in Offshore Frac Hose Rig Hookups

Abstract

Large volume sand control and reservoir stimulation methods in the offshore market require connecting a heavy, low-yielding flexible hose from the service company stimulation vessel to the drilling rig or platform (Henceforth referred to as "rig"). From there it is typically connected to rigid high pressure treating line routed to a manifold. The use of a flexible hose anchoring point pre-installed on the rig greatly reduces exposure to accidents by eliminating dangerous chaining up methods to secure the hose to the rig. This device may remain on the rig for future pumping events. The use of a flexible hose rig-anchoring point provides an engineered solution to reduced human, hands-on interaction when securing the treatment hose to the rig prior to a sand control or stimulation pumping event. Pinch points for hand and foot interactions are eliminated. Placing workers in precarious situations on the outboard of the rig's handrail, high above the water surface is prevented by use of a "drop-in and lock-in" landing plate that supports the flexible hose and its connection flange in a vertical position. This process saves time by eliminating repositioning measures when having to secure the flexible hose to some fixed object on the outboard side of the rig such as handrail posts or mooring cleats using chains. Introduction As offshore well treatment options evolved from small volume, low rate acid stimulations and gravel packs to formation fracturing treatments, the size and scope of equipment requirements grew as well. For years, portable skid mounted pumps and blenders were delivered to location, spotted on the pipe deck and connected to the treatment point with rigid high pressure treatment lines.1 That process is still in use today for smaller-scale treatments. It's much more common for the operator to contract specialized stimulation vessels capable of pumping hundreds of thousands of pounds of manufactured proppant for frac treatments in excess of 10,000 psi.4,5 Lower pressured treatments may exceed 50 barrels per minute.2 The latest generation of stimulation vessels must remain on location without mooring to the rig for longer than twelve hours in order to rig up, test lines, and perform numerous treatment evaluation routines before pumping the actual treatment. Dynamic positioning systems on the vessels use satellite global positioning and rotating thrusters on the boat all tied together by computers to control the position of the vessel during the treatment. Although Chicksan® swivels can be made up on rigid, high pressure treatment lines, the constant movement of the boat in even moderate sea conditions would make it impossible to perform a treatment safely or efficiently. Multi-layered high pressure flexible hoses were designed and built for the application described above. (For the purpose of this paper the flexible high pressure hose, frequently called coflex hose in the field, will be referred to as the frac hose.)1 Frac hoses are constructed with multiple non-bonded layers of thermoplastic linings resistant to acids and solvents, steel armor sheaths, cross wound synthetic fibers and steel wire shrouded with a stainless steel outer wrap. Stimulation vessels most often employ three or four inch internal-diameter hose.2 The industry has begun to incorporate five inch internal diameter. frac hoses on some vessels, primarily in deepwater applications. Due to the specialized multi-layered construction, the outside diameter of the frac hose can exceed seven inches and weigh as much as 60.6 pounds per foot empty. The end fittings of the hose include handling collars and integral connectors.

Scientometric Review and Thematic Areas for the Research Trends on Marine Hoses

“…As seen in Figure 4, it was observed that the highest generated publications were 19 publications in 2020, followed by 14 publications in 2014 and 2016, then 13 documents in 2019, and 12 documents in 2021. However, there are limited publications found on the installation of marine hoses [160][161][162][163][164][165][166][167][168][169][170] compared to other marine systems [171][172][173][174][175][176][177][178][179][180].…”

“…As seen in Figure 4, it was observed that the highest generated publications were 19 publications in 2020, followed by 14 publications in 2014 and 2016, then 13 documents in 2019, and 12 documents in 2021. However, there are limited publications found on the installation of marine hoses [160][161][162][163][164][165][166][167][168][169][170] compared to other marine systems [171][172][173][174][175][176][177][178][179][180]. As observed in Figure 5a, the highest publications by subject area were in engineering, with 212 publications (42.7%), energy, with 99 publications (19.9%), earth and planetary sciences, with 46 publications (9.3%), environmental science with 23 publications (7.4%), chemical engineering with 23 publications (4.6%), materials science with 21 publications (4.2%), and agricultural and biological sciences with 16 publications (3.2%), among other subject areas.…”