Title: Super insulated wells to protect permafrost during thermal oil recovery

Authors: Cristo Marques, Louis M. Castanier, A.R. Kovscek

Addresses: TOTAL Pau, France; Energy Resources Engineering, Stanford University, 367 Panama St, Stanford, CA 94305 USA. ' Energy Resources Engineering, Stanford University, 367 Panama St, Stanford, CA 94305 USA. ' Energy Resources Engineering, Stanford University, 367 Panama St, Stanford, CA 94305 USA

Abstract: In cold environments, wellbore heat losses are significant and limit the applicability of thermal recovery. Our study focuses primarily on the problem of wells penetrating permafrost. The experimental component determines thermal conductivity versus temperature of nanomaterial insulators (aerogels), fibreglass, thermolastic insulation, and carbon fibres. A comparator thermal conductivity apparatus as well as direct measurements using heat flux sensors were developed. Semianalytical and numerical models were also created to design a superinsulated well. The models incorporate various composite insulations. Well failure/stability is inferred from the rate of thaw-front propagation. A key parameter is the insulation thermal conductivity versus temperature that is measured directly. Measurements of conductivity agree with literature values at ambient temperature. Aerogels (0.012-0.025 W/m K) are half as conductive as fibreglass (0.03-0.045 W/m K) and three to four times less conductive than thermolastic insulation and carbon fibres (0.04-0.067 W/m K) for temperatures between 40 and 140°C. The wellbore heat loss and thaw front propagation model indicates that aerogels alone or aerogels in a composite with more conductive insulation may meet the requirements to avoid well failure, even for very high temperature fluids and over long time.

Keywords: wellbore heat loss; permafrost; thermal oil recovery; insulation; superinsulated wells; thermal conductivity; temperature; nanomaterial insulators; aerogels; fibreglass; thermolastic insulation; carbon fibres; namoaterials; heat flux sensors; modelling.

DOI: 10.1504/IJOGCT.2011.037742

International Journal of Oil, Gas and Coal Technology, 2011 Vol.4 No.1, pp.4 - 30

Published online: 26 Dec 2010 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article