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ing the well quickly to production. No fluids are introduced, which diminishes the risk of reservoir damage, and surface read-outs allows the crew to monitor the operation in real-time. All tools are equipped with passive fail-safe mechanisms that prevent the tools from getting stuck in case of power- loss. Often a Welltec Release Device run on battery is incorporated into the toolstring, which auto-releases the tools after a set time interval with no cable power creating a fsh. In fact, the latter is mandatory in op- erations on the Norwegian Continental Shelf.

Welltec introduced the original Well Tractor and thus has nearly two decades of experience with this type of conveyance. The lightweight design of the

Well Tractor and the innovative nature of Welltec meant that it was only natural to be part of the se- lect few that set out to pioneer rigless and riserless interventions when RLWI possibilities were first

Bailer section packed with dense asphaltenes after explored back in 2000.

the flter is removed. Asphaltenes set once exposed

During this specifc intervention, two e-line tools to lower temperature; when in the well under a were employed: the Well Tractor and the Well certain temperature the asphaltenes are stickier.

Cleaner RCB. The Well Tractor is a conveyance tool that enables interventions in all environments. It in order to determine the appropriate action. extends the reach of intervention tools and provides The analysis confrmed that the material recovered pinpoint accuracy irrespective of the well inclination. was primarily asphaltenes with some entrained oil

During milling or cleaning operations it functions as and Anadarko suspects that these will continue weight-on-bit and counters the reactive torque from throughout the well. The only intervention option the rotation. with the current technology is thus a coiled tubing

The Well Cleaner RCB is a unique tool that incor- (CT) clean-out with a riser and rig, and at this point porates built-in bailers to capture debris. RCB means it is uncertain if production will be restored.

reverse circulating bit; it is a system that allows Based on the experiences with this case well, debris to pass through the milling bit and into the Anadarko would like to see development of CT bailer sections of the toolstring. technology for use with RLWI to address larger de-

In November 2012, Anadarko initiated its first posits of asphaltenes. The RLWI method is still under

RLWI operation. The purpose was to set a subsurface evaluation by Anadarko and they see a potential for safety valve (SSV) across a failed, closed, surface addressing more discrete deposits with downhole controlled subsurface safety valve (SCSSV). The millers like the Well Miller and Well Cleaner.

downhole conditions were unknown, as the well had The case example was Anadarko’s frst attempt at not been re-entered since it was put on production. RLWI operations and it was achieved in a world re-

During the initial slickline gauge run, the toolstring cord water depth for RLWI e-line operations of 3991 kept hanging up after only about 1000ft. (305m) in ft (1216 m). It was also the frst time asphaltenes have the well. The frst attempted to remove the blockage been recovered using e-line cleaning tools.

OE REVIEW was with chemicals. However, as this was unsuc- cessful, it was decided to deploy a Well Tractor and Ole Eddie Karlsen is VP of global

Well Cleaner RCB to try to remove the obstruction. subsea operations at Welltec Norway. He

The toolstring tractored past the slickline hold up has more than 20 years of experience in depth (HUD), cleaning while moving at 10 f/h. and the oil and gas sector, with previous continued down to 5727 ft (1746 m) , where an ob- roles at Vetco Gray and ABB Offshore struction was encountered and the toolstring became Systems. stuck. The toolstring was worked free and pulled out of the hole. At surface the bit was found to be packed Steve Ashcraft is a senior staff produc- with solid debris, while the bailer sections were flled tion engineer with Anadarko Petroleum with dense, hard-packed asphaltenes. These had not Corporation, currently assigned to the been anticipated in the well. Lucius facility. He has 18 years indus-

Thus, Anadarko decided to cease operations try experience in drilling, completion pending analysis of the recovered samples. As “as- and production operations. His offshore phaltenes” is a common denominator for a class of assignments include Snorre A tension leg aromatic-type substances, which are defned on the platform (TLP), Valhall, BC-10, Terra Nova, Boomvang Spar and Marco basis of their solubility, proper analysis is necessary Polo/K2 TLP.

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