RETRIEVING ASPHALTENES, RLWI WATER DEPTH RECORD

Background

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 3,991 feet (1,216 m). The well had not been re-entered since it was put on production, hence downhole conditions were unknown. A slickline gauge run was attempted first, but the toolstring kept hanging up after only ~ 1,000 ft (305m) in the well.

OPERATION

After multiple failed attempts with slickline, the Well Tractor® and Well Cleaner® RCB were rigged up and run in hole to mill through the obstruction. This toolstring was able to tractor past the previous depths were slickline held up and continued down to 5,727 ft (1,746m), where a blockage was encountered. The Well Cleaner RCB was engaged and successfully cleaned the well for 1,863 ft (568m) before becoming stuck. The toolstring was worked free and recovered to surface. There the bit was found packed with solid debris while the bailer sections were filled with dense, hard packed asphaltenes, which had not been expected. The operator concluded that these deposits would likely be present throughout the well. Therefore they decided that it would be best to analyze the samples recovered by the Well Cleaner RCB and prepare a plan before attempting to mill out potentially tens of thousands of feet of deposits.

ACHIEVEMENTS

Based on the successful recovery by Welltec® the operator gained valuable information about the downhole conditions, which enabled them to make an informed decision on how best to proceed. The decision was to suspend further operations until the recovered asphaltenes were fully analyzed. This operation was the first time asphaltenes had been recovered using e-line cleaning tools. It was also the world record for water depth, but since then we have beaten that record considerably by performing an operation at 8,087 ft water depth in the Gulf of Mexico.

WELL TYPE: PRODUCER
MAX. TEMPERATURE: 100 F (38 C)
MAX. DEPTH: 5,731 FT (1,747 M)

 

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This operation was achieved in a world record water depth for RLWI e-line operations of 3,991 ft (1,216 m) and was the first time asphaltenes have been recovered using e-line cleaning tools.