Investigation of the elastic material properties of Class G cement

Abstract

Class G cements are sulfate-resistant Portland cements with different setting time requirements and have a common field of use in the oil industry. Compared to other American Petroleum Institute class cements, Class G has a utilization of more than 95% worldwide in oil well applications. Different additives are used together with Class G cement to achieve optimum hardening conditions. In this study, the elastic material properties of high sulfate-resistant (HSR) Class G cements are investigated for a special case implemented in solution mining. There are no published studies to date on the mechanical properties of Class G oil well cements for more than 3 days of curing time and various water-cement ratios. Uniaxial compressive strength, Young's modulus, and Poisson's ratio determination are carried out on a total of 108 samples with different curing times (2, 7, and 14 days) and water-cement ratios (0.4, 0.5, 0.6, and 0.8). Laboratory results were subject to Dixon's Q test for outlier elimination and were analyzed by fitting a multivariable nonlinear regression model to estimate uniaxial compressive strength and Young's modulus.

Characteristics of underwater cast and cured geopolymers

“…Even more, the GC-2.00 can become stronger and more ductile than the GC-1.78 in the 35 ppt curing solution. According to some published work [41,42], the Young's modulus of OWC cured for 14 and 20 days is nearly 12 and 14 GPa, respectively, which agree well with those of the underwater cast and cured OWC. The relatively lower elastic modulus of the air-cured OWC (e.g., <6 GPa) obtained in this study may be caused by the fact that the adopted design mix (e.g., water to cement ratio) is developed for underwater casting and curing, but not for air-curing.…”

Design of aromatic polyamides to modify cement performance under triaxial cyclic tests

“…Here, a series of triaxial compression tests are performed to examine the fatigue behavior of different cements under cyclic loading (Autolab 3000, NER, USA). [2,12,24,25] Test results allow for fatigue failure lifetime predictions to be made by extrapolations from short-term fatigue tests. [4] In each cyclic loading series, an axial stress of 40 MPa is applied.…”

“…The resulting strain-stress curve and loops behavior at 30 MPa confining pressure (P c ) illustrate overall cement integrity (Figs. 2,3,4). Uniaxial cyclic stress test uses 10 MPa of axial loading (blue arrows) and unloading (red arrows) to show cement response.…”

“…Oil and gas wells generally go through mechanical stress and thermal cycles during production. [1,2] To mimic such wellbore conditions in the lab, a triaxial loading cell measures cement performance, permanent deformations, fractures, and ultimately mechanical fatigue and failure under axial and confining pressures. With triaxial cyclic stress tests, cement integrity is quantitatively measured by cumulative damage models commonly used in applied metallurgy and engineered materials.…”