TX 75083-3836, U.S.A., fax 01-972-952-9435.
AbstractUncontrolled heat transfer from production tubing to outer annuli, especially in deep-water riser sections, can cause the deposition of sludge, paraffin and asphaltene materials and contribute to the formation of gas hydrates. It also can limit the shut-in time if there is a need to shut down the well for remedial operations. Generally, deep-water risers can be insulated externally, or alternatively, insulated by placing nitrogen gas into the riser annulus. In recent years, a new water-based thermal insulating fluid system with superior thermal properties has been developed and used in field applications. This new system provides an ideal rheological profile to significantly reduce fluid convection caused by temperature differential and to facilitate fluid placement into the riser annulus. This system has been successfully used as an alternative to the current insulation method in deep-water risers in the Gulf of Mexico.Laboratory-scale equipment and a full-scale test well were constructed to evaluate the thermal insulation properties of fluids. This paper will detail both testing procedures and methods. Steady-state heat transfer and cool down test results on the new insulation fluid will be reviewed for both set-ups. The results will be discussed along with the results from similar tests on conventional brine based packer fluid, current insulation fluids, as well as nitrogen (air) and argon. The fullscale test data will be discussed in relation to modeling wellbore heat transfer. Field cases in GOM are also summarized to demonstrate the effectiveness of this fluid system.