Thermal Stability of the Cement Sheath in Steam Treated Oil Wells

Abstract

The material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42Les renseignements dans ce document sont protégés par la Loi sur le droit d'auteur, par les lois, les politiques et les règlements du Canada et des accords internationaux. Ces dispositions permettent d'identifier la source de l'information et, dans certains cas, d'interdire la copie de documents sans permission écrite. Pour obtenir de plus amples renseignements : http://lois.justice.gc.ca/fr/showtdm/cs/C-42 Considerable work has been done in the past on the phase equilibria and physical properties of thermal cements heated directly to high temperatures. In thermal recovery oil wells the cement sheath is, however, cured for days to years at temperatures of 40°C or less before it is subjected to steam injection temperatures of up to about 320°C. The effects of this alternative curing regime have not been well documented. Here, the impact of pre-curing samples for 1, 14 and 28 days at 35"c before heating to 230°C on phase assemblages, morphologies and physical properties of thermal cement were investigated. Control samples included thermal cements heated directly to high temperature as well as samples cured only at 35 °C. Xonotlite formed the predominant phase in the pre-cured thermal cements instead of the tobermorite found in the control sample heated directly to 23o"c. Although all pre-cured samples were predominantly xonotlite, their morphological characteristics of the phase assemblages were found to vary distinctly with pre-curing time. Significant differences between the pre-cured and directly cured samples were also observed in terms of porosity, permeability and mechanical behaviour.

Self‐Sensing Cementitious Composites with Hierarchical Carbon Fiber‐Carbon Nanotube Composite Fillers for Crack Development Monitoring of a Maglev Girder

“…In addition to CF reinforcement at macroscale or microscale, CNT can even bridge the nano-scaled cracks and transfer load from CF to itself, thus delaying crack generation and propagation. [47,[64][65][66][67][68] In addition, as shown in Figure S7, Supporting Information, the XRD and TG results both revealed that the addition of CF and CF-CNT had no influence on the compositions of SSCCs' hydration products while can promote their hydration degree to some extent as observed by the higher overall TG mass losses than the blank specimen, consistent with previous studies. [26,69] As compared, the CF-CNT performed more positively in the promotion of SSCC's hydration degree over the CF due to the nucleating effect of CNTs, which further elucidates the reinforcing mechanisms of CF-CNTs.…”

“…In addition to CF reinforcement at macroscale or microscale, CNT can even bridge the nano‐scaled cracks and transfer load from CF to itself, thus delaying crack generation and propagation. [ 47,64–68 ]…”

Improvement on Mechanical and Piezoresistivity Properties of Cementitious Binder by Using Surface Oxidized Multi-Wall Carbon Nanotubes

“…It is an essential challenge to make the exceptional properties of CNT exhibited at the nanoscale transferred to the macroscale, the dispersing efficiency and CNT/cement bonding should be intensively explored prior to introducing CNT into cementitious binder. Makar et al [3] tried to develop an ethanol/sonication technique to disperse CNT in cement particles. Mi et al [4] employed surfactant enwrapping process to improve the dispersion efficiency.…”

Chemo-Physico-Mechanical Behavior of Class G Oil Well Cement Pastes

“…In 1952, the API committee adopted standards for six classes of cements used in oil and gas well cementing operations. The mechanical properties of the cement pastes are highly dependent on the curing conditions, which vary along the wellbore depth and corresponding to the exposure to the formation fluids with different conditions [85][86][87]. It is worth noting that the cement pastes used in the oil and gas industry has very low permeability [88].…”