Insights into the physical and chemical properties of a cement-polymer composite developed for geothermal wellbore applications

Journal Article · Fri Mar 01 00:00:00 EST 2019 · Cement and Concrete Composites

DOI:https://doi.org/10.1016/j.cemconcomp.2018.12.022· OSTI ID:1503167

Rod, Kenton A. ; Nguyen, Manh-Thuong; Elbakhshwan, Mohamed; Gills, Simerjeet; Kutchko, Barbara; Varga, Tamas ; Mckinney, Adriana M.; Roosendaal, Timothy J.; Childers, M. Ian; Zhao, Chonghang; Chen-Wiegart, Yu-chen Karen; Thieme, Juergen; Koech, Phillip K.; Um, Wooyong ; Chun, Jaehun ; Rousseau, Roger; Glezakou, Vassiliki-Alexandra; Fernandez, Carlos A.

To isolate injection and production zones from overlying formations and aquifers during geothermal operations, cement is placed in the annulus between well casing and formations. Wellbore cement can fracture due to chemical and physical stress. A polymer-cement (composite) with self-healing properties, stable at high temperatures, was recently developed by our group. Here we present data on the elemental distribution, mineral composition, internal microstructure, and tensile elasticity of this composite and how it compares to cement without polymer (control cement). Entrapped air porosity was similar between control cement (0.44% by volume) and composite (0.22% by volume). Total voids increased with polymer content in the cement (10% and 25% composite), and polymer was found to fill most of these voids. Polymer appears to act as a (cement hydration) retarder increasing the amount of unhydrated silicate minerals in the matrix. Tensile elasticity was improved for composites as compared to control cement, suggesting that the composite materials perform better under mechanical stress. Density-functional calculations reproduce the drop in Young’s modulus by about 60% observed experimentally when polymer is added to the cement. In addition, calculations indicate that the bonding interactions between the cement and polymer remain stable over the range of strain studied.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1503167
• Report Number(s): PNNL-SA-131466
• Journal Information: Cement and Concrete Composites, Vol. 97, Issue C; ISSN 0958-9465
• Publisher: Elsevier
• Country of Publication: United States
• Language: English