Innovation in intervention

Welltec’s well tractor has transitioned from an unlikely vision to a solid reality now deployed in deepwater wells. OE explains.

Image from iStock.

Sometimes it takes an outsider to pinpoint how matters can be improved. A case in point was illustrated when, 25 years ago, a young, Danish MSE student looked at the oil industry and wondered if interventions could become more efficient.

Jørgen Hallundbæk saw a need and was determined to address it by inventing a new way of intervening in wells. Thus was born the e-line deployed Well Tractor that could deploy logging tools into horizontal and highly deviated wells without the use of heavier intervention methods like coiled tubing or drill pipe. Industry workers thought it couldn’t be done, but Hallundbæk, who studied at the Technical University of Denmark, believed in his idea and in transforming the industry.

Today, the Well Tractor has become standard equipment to many operators. Denmark-based Welltec, the company that was set up to develop the tool, says a 10ft-long Well Tractor is basically able to do the same work as a coiled tubing unit, but faster, safer, more cost-efficiently and with reduced size equipment (reduced footprint) with fewer manning requirements (reduced manhours) and just an e-line unit. Today, its use is now being deployed into ever deeper waters.

Establishing well access at almost 4000ft water depth

An operator in the Gulf of Mexico planned to set a lock-open sleeve across a failed subsurface safety valve. The operation was conducted as a riserless light well intervention (RLWI) on a subsea well in a water depth of 3991ft. The downhole conditions were unknown because the well had not been re-entered since it was put on production.

After multiple failed attempts with slickline, a Well Tractor and Well Cleaner RCB milled through the obstruction, tractoring past the previous slickline hang up depths. At 5727ft, a blockage was encountered. The Well Cleaner RCB removed it before further cleaning the well down to 7590ft before becoming stuck.

The toolstring was worked free and recovered to surface where the bit was found packed with solid debris and the bailer sections filled with dense, hard packed asphaltenes, which had not been expected. The operator concluded that these deposits would likely be present throughout the well and decided to analyze the samples instead of attempting to mill out potentially tens of thousands of feet of deposits.

Hallundbæk.

Being able to access the well and recover samples provided valuable information about the downhole conditions, which enabled the operator to make an informed decision on how best to proceed. This operation was achieved in a world record water depth for RLWI e-line operations and was the first time asphaltenes had been recovered using e-line cleaning tools.

Ultra deepwater RLWI clean-out

Since then, Welltec has beaten that record significantly. At 8087ft water depth in the Gulf of Mexico, the Well Cleaner PST was used to clean above a plug to confirm the fishing neck was clear.

Welltec’s solution provided several benefits over slickline, including larger recovery volume, CCL depth correlation and the ability to indicate whether the fishing neck was clear for the pulling tool. Further debris was suspected above the plug, so the Well Cleaner RCB was used to retrieve the debris before the Well Stroker was run to fish the plug because the slickline was unable to do so.

The above shows that RLWI in ultra-deepwater works and that the boundaries of what can be achieved in the industry are constantly pushed. It’s only a matter of changing the game and believing in an idea.