The first high-temperature application of ISOTHERM NT™ advanced nonaqueous-based insulating packer fluid minimized thermal stress on the liner and maintained well integrity while an operator brought two previously suspended offshore wells onto production.
An operator in Mexico was bringing two previously suspended offshore wells onto production in the Pokoch Field. The operator planned to work on the completion tieback string using patches and needed to minimize heat transfer from the production flow to the outer annuli.
Initially, the operator sought an oil-based insulating packer fluid that could withstand temperatures above 275 degF [135 degC]. However, the planned flowing of the completion at a very high rate would result in flowing temperatures of up to 310 degF [154 degC]. To avoid excess stress on the patches, packer fluid viscosities would have to be maintained in these high-temperature conditions over an extended period of up to 7 days.
M-I SWACO, an SLB company, recommended ISOTHERM NT advanced nonaqueous-based insulating packer fluid in combination with the POLAR-VIS™ insulating packer fluid viscosifier. The M-I SWACO team selected the single-sack system—traditionally used in arctic and low-temperature reservoir applications—for its low thermal conductivity and long-term thermal stability. In addition, unlike other systems, ISOTHERM NT packer fluid eliminates the need for a breaker or activator to deliver the required rheological properties.
The operator pioneered the world’s first use of ISOTHERM NT fluid in high-temperature conditions, mitigating thermal fatigue and completing the wells as planned. For maximum efficiency, M-I SWACO mixed the treatment at the liquid mud plant (LMP) instead of the rig, which minimized footprint, optimized mixing quality, and saved more than 36 hours of mixing time at the rig site. The field team was able to apply the treatment using existing cementing equipment with no delays, contamination, or pumping issues. In total, M-I SWACO pumped 385 bbl of insulating packer fluid over an 8.5-hour period—spotting 110 bbl and 275 bbl of the ISOTHERM NT fluid treatment into the respective wells.
ISOTHERM NT and POLAR-VIS are marks of M-I L.L.C., an SLB company.
