Catenary concentric coiled tubing sand-vac solution exceeds production target by 185% 12 Jun 2015

Using its Sand-Vac™ cleanout system with a specially designed concentric coiled tubing (CCT) reel and string for the first time, Baker Hughes provided a sand solution on four wells offshore Malaysia that had been shut in since 2011.

Post-operation production showed an increase of 185% in expected daily production.

The operator faced several challenges, including low bottomhole pressure, restricted platform access and crane capabilities, and jack-up vessel availability. The problem was further compounded by high sand production in all the wells that prohibited production and access to producing zones in the lower completion. Previous cleanouts using conventional coiled tubing and nitrogen had been unsuccessful.

“The job needed to be performed from a work barge in a catenary style, meaning that the injector head, blowout preventers, and power pack were on the platform, but had to be operated from a barge,” said James Larke, Baker Hughes Technical Manager in Malaysia. “Our advanced wireless catenary unit made it possible to complete the operation with only the coiled tubing and three flexible lines connecting the barge and the vessel. Due to the nature of the CCT—designed to flow returns back to surface—all returns had to be routed away from the platform and onto the barge.”

After an analysis and planning session, the operator and Baker Hughes decided to use the Sand-Vac cleanout system with a specially designed concentric reel and string. The Sand-Vac system uses CCT combined with a proprietary downhole switchable jet pump to remove solids and liquids from ultralow pressure wellbores that are not treatable with standard circulating methods. The operational plan also called for building a specialised coiled tubing connector that would enable conventional operations (such as fishing and sleeve manipulation) to be performed with CCT.

“This was the first time that Sand-Vac technology and catenary CCT were used together to perform a cleanout operation,” Larke said. “The results were extremely impressive.”

A total of 15,650 lb (7.1 metric tonnes) of sand was recovered from the four wells, including 11,900 lb (5.4 metric tonnes) in just one run. “The 112-day operation ran smoothly with no safety incidents,” Larke said. “The operator hoped to achieve a target production of 550 bopd [87 m3/d] after the intervention. Post-operation production was recorded at 1,570 bopd [250 m3/d], an increase of 185% in expected daily production.”