The Highly Cost-Effective Workover Option For Marginal Wells

For example, coiled tubing units allow workovers on an underperforming well while still producing, the ongoing production plus the resulting uplift achieved may still not cover the cost of a specialist CT intervention should oil prices remain comparatively low.

The place for novel thinking
In addition to new technologies that address oilfield challenges, novel technical solutions can sometimes be found by applying existing systems in creative new ways. One such example is coil hose.

With its basic construction of a steel core surrounded by an elastomer, coil hose is unlikely to be considered an advanced technology. Yet in specific circumstances it offers advantages over coiled tubing.

The components of an innovative fluid placement system
In applications with lower pump rate requirements, coil hose can be used to place well treatment fluids with precision using smaller scale equipment.

Cleansorb fluid systems are the perfect choice for coil hose deployment since their non-aggressive nature ensures they don’t attack the steel core of the hose. The fluids also feature a built-in time delay mechanism before the treatment is activated. This allows them to be pumped slowly and remain in the hose for longer without adversely impacting the coil hose itself or the treatment outcome.

With its smaller footprint and rapid mobilization, coil hose can be a cheaper alternative to bringing in a coiled tubing unit and crew. Applicable both on and offshore, combining it with Cleansorb fluid systems makes it the ideal choice to perform a low-cost well intervention.

Proven in the field
An operator needed to carry out a workover treatment on an underperforming North Sea well. The well’s low productivity was thought to be due to damage caused by a build-up of OBM residues. The operator’s initial intention was to re-perforate casing beyond the drilling damage zone, but given the marginal status of the well it was believed it might prove more cost-effective to treat the drilling damage itself, if a low-cost intervention method could be found.

The unique combination of coil hose and innovative chemistry from Cleansorb was selected for the project. As well as being kinder to the hose itself, Cleansorb products are non-hazardous and low hazard for personnel and the environment; a key factor in offshore operations such as in the North Sea.

Directly following the treatment, the operator saw a strong increase in production, validating their original suspicion that the productivity loss had been caused by drilling damage – and all without the need and expense of coiled tubing or re-perforating.

Greater options, more possibilities
Building on these achievements with coil hose, Cleansorb is now investigating other possible ways of pumping delayed action fluid treatments to subsea wellheads, for example using existing capillary lines. If successful, this method should minimise the need for specialized equipment or personnel – reducing costs and risks offshore.