An evaluation of the reduction of heat loss enabled by halloysite modification of oilwell cement

Abstract

The increasing reliance on steam-assisted gravity drainage (SAGD) to access unconventional bitumen deposits within the sub-Arctic necessitates the development of robust cement sheaths for oilwell cementing. Such cement sheaths can potentially increase the energy efficiency of the SAGD process by reducing heat loss while maintaining mechanical integrity upon prolonged exposure to cyclic thermal stress. Modifying oilwell cement by the inclusion of hydroxyethylcellulose-functionalized halloysite nanotubes (HEC-HNTs) within the cementitious matrix results in a high density of enclosed void space and disparate interfaces, which serve to scatter phonons and reduce thermal conductivity. In this study, we have systematically evaluated the influence of HEC-HNT loading on the thermomechanical properties of cement with and without the addition of calcium chloride as an accelerator and have correlated the reduction of thermal conductivity to the distinctive microstructure of the nanocomposite cement. The incorporation of HEC-HNTs in thermal cement reduces the thermal conductivity from 0.856 W m −1 •K −1 to 0.206 W m −1 •K −1 without substantially altering the compressive strength. Model systems mimicking SAGD oilwell cement sheaths have been prepared from umodified and modified (incorporating HEC-HNT) cement and subjected to cyclic thermal stress emulative of SAGD conditions. Cement sheaths constructed from the modified cement with CaCl 2 maintain a higher temperature gradient as compared to unmodified cement with CaCl 2 ; a 12 °C increased temperature differential between hot and cold surfaces is observed for a 4.5 cm thick sheath with a considerably shallower rate of increase in temperature. Aggressive thermal cycling (20 h at 250 °C followed by 4 h at 25 °C) for 20 days brings about a 20% reduction of compressive strength. The combination of additives facilitating thermal insulation and mitigating differential shrinkage provides an attractive means of oilwell cementing for SAGD applications wherein cyclic thermal stresses are operational and energy efficiency is of paramount importance. Extrapolating the considerably increased temperature differentials between hot and cold ends within model systems to entire wells portends significant energy savings and reduction in amounts of injected steam.

In situ Resource Utilization and Reconfiguration of Soils Into Construction Materials for the Additive Manufacturing of Buildings

“…The amount of clay added in the cement in the study is along the lines of soil added to concrete in previous reports (Lei and Plank, 2012;Li et al, 2017). The reduction of thermal conductivity derives from the inclusion of nanoscopic voids and the phonon scattering at interfaces within the composite (Cho et al, 2018;Udayakantha et al, 2019).…”

“…Such an approach provides a sharp reduction of thermal conductivity, thereby mitigating heat losses through oilwell cement during thermal extraction processes. Specifically, we have examined the incorporation of hydroxyethylcellulose-functionalized halloysite in class G Portland cement (Cho et al, 2018;Udayakantha et al, 2019). Approximately 2-5 wt.% of halloysite nano-clays with nanotubular voids are added to the cement achieving 7 days compressive strengths as high as 15.71 MPa (with even a slight enhancement of compressive strength with respect to control specimens without halloysite) whilst engendering upto ca.…”

A Materials Science Perspective of Midstream Challenges in the Utilization of Heavy Crude Oil

“…Hence, any loss of thermal energy input during the operation of the SAGD process has a direct impact on the economic viability of the process. The energy losses occur primarily through the surfaces of pipelines as a result of the high thermal conductivity of pipeline materials (mostly structural steels) and large thermal gradients across these conduits given frigid external temperatures in the Athabasca region . Thermal conductivity is a measure of heat transfer efficiency within a material under the influence of a temperature gradient.…”

“…Panel (D) reprinted from Materials and Design, 57, Albdiry, M. T.; Yousif, B. F., Role of silanized halloysite nanotubes on structural, mechanical properties and fracture toughness of thermoset nanocomposites, 279–288, 2014, with permission from Elsevier . Panels (E, F) republished with permission of Engineering Research Express from An Evaluation of the Reduction of Heat Loss Enabled by Halloysite Modification of Oil well Cement, Udayakantha, M.; Cho, J.; Liu, K.-W.; Mukhopadhyay, A.; Gupta, S.; Hong, C. Y.; Banerjee, S., 1, 2, 2019 …”

“…Despite rapid technological advancements that have rendered SAGD methods an economically viable approach for oil production in the Canadian Oil Sands, the production of oil by such methods remains considerably more expensive as compared to extraction of sweet light crude in the Permian Basin or from plays in the Persian Gulf. As such, there is considerable interest in improved recovery rates through the incorporation of chemical additives, energy-efficient thermal cementing to prevent heat loss during SAGD (or incorporation of thermal insulation more generally across the SAGD infrastructure), more optimal separations of the extracted emulsions, protection of base metal components exposed to harsh corrosive environments, and the design of solutions to midstream transport that mitigates myriad current challenges with pipeline and railcar transportation. − …”