The method features physical removal of the hydrate plug, combined with changing the well fluid environment above the plug to prevent the hydrate plug from re-forming. Further, one removes the obstacle without the risk of the toolstring being lifted by gas migration when penetrating the well blockage.
Suitable for all wells
The innovation involves novel and patent pending wireline collector/discharger technology and a modification to existing wireline tractor milling equipment. By this means, hydrate plug removal operations can be performed on all types of petroleum wells, however the method is especially applicable to riser less light well Intervention (RLWI). Traditionally, on a subsea well, removal of a hydrate plug could be a highly costly exercise depending on type of equipment involved (in many cases, a drilling rig would be required to support the conveyance of a coil tubing operation).
As described above, the system discharges hydrate dissolver on top of a hydrate plug simultaneously to milling the plug, all operational steps taking place in the same run. Reloading the system with hydrate dissolving agents is done in the wireline lubricator mounted on top of the subsea tree, without breaking any pressure seals. The number of refilling sequences depends on the actual length of the hydrate plug and the capacity of the collector/discharger equipment.
The value added is considerable, with potentially large savings and significant operational improvements compared with current art techniques. The savings could be tens of million dollars per year.
The most profitable effect is the ability to as fast as possible gain value from a well in service.
Existing solutions for hydrate plug removal are somewhat ineffective, and involve a risk of re-establishing the hydrate plug, and/or are very time consuming. Also, current art operations involve a relatively high risk of uncontrolled tool motion when penetrating the hydrate plug (whereupon high pressure from below the plug is released to the tool surroundings).
In summary, significant savings may be gained on subsea wells through effective usage of vessels for hydrate plug removal. Further to a successful introduction of the technology described herein, there will no longer be a need for more advanced operations such as coiled tubing operations from a floating rig or other costly services.
The technology is based on equipment that has been in service for a longer period of time, in the form of a screw type debris bailer. Novel aspects are the cutting/milling feature, and also the sealable transport chamber for transporting hydrate dissolver.
The technology solution represents a service and could be used on all types of petroleum wells worldwide. Hydrate plugs may not be a frequently occurring problem, but do - when they occur - represent potentially very significant losses in production or operational time. Consequently, the innovation represents a very significant value potential. Also, being a service conveyed on wireline, the innovation represents significant benefits from a HSE as well as a logistical point of view.
Despite a relatively modest direct potential, the indirect value is significant, as technologies for addressing high-potential situations in wells form a very valuable part of a well servicing toolbox when bidding for contracts.
The customer will benefit from getting access to a method for hydrate removal that is significantly simplified and cost effective compared with prior art. In particular, subsea hydrate plugs can be treated by means of a cost effective RLWI operation.