High Performance Aqueous Insulating Packer Fluid Improved Flow Assurance and Reduced Annular Pressure Buildup in Ultra Deepwater Wells

Abstract

Deepwater production well design and equipment installation present multiple challenges. One major problem is the uncontrolled heat transfer to outer annuli which can be detrimental to the integrity of the well. Annular pressure buildup (APB) could result in casing failure and heat loss from the production tubing causes dramatic loss of well productivity due to the deposition of paraffin and asphaltenes and could contribute to the formation of gas hydrates. Vacuum insulated tubing (VIT) was initially utilized in the deepwater well completions to help alleviate well failure caused by APB. The operator requested an alternative to VIT that would provide the following benefits: Reduced costs Minimization of APB or similar to VIT Increased flow assurance Ability to apply the downhole tools required to be installed in the production string Ease of placement was also an issue. Typically VIT takes special handling equipment, long lead times, and adds 10-12 hours of rig time for running of the production tubing. Customized high performance aqueous-based insulating packer fluid (IPF) proved to be a reliable alternative to VIT. A properly designed fluid having a density of 10.0 lb/gal and thermal conductivity (k) of 0.176 BTU/h ft°F was carefully prepared. The unique thermal-gelling characteristics of this state of the art fluid allowed for easy, rapid placement of the fluid in the well annulus. Once in the wellbore, the fluid has provided increased flow assurance as well as a reduction in APB thus resulting in increased well flow rates and improved profitability. Repeated field applications of this tailored aqueous IPF helped in achieving an overall cost reduction of more than 64% compared to utilizing conventional VIT. This paper presents detailed fluid formulations with laboratory data generated by specialized equipment, and discusses the fluid design criteria along with the reported data and economics.

Transient prediction of annular pressure between packers in high-pressure low-permeability wells during high-rate, staged acid jobs

“…Since the 1980s, scholars all over the world have conducted a great deal of research on the annular pressure in wellbore enclosed space, examined the annular pressure induced by the rise in wellbore temperature, established the related theoretical calculation models (Halal et al, 1994;Hu et al, 2012;Oudeman and Kerem, 2006;Yin and Gao, 2014) and raised some risk mitigation measures in accordance with different well conditions and requirements (Ezell et al, 2010;Sathuvalli et al, 2005;Tahmourpour et al, 2010;Williamson et al, 2003).…”