Ductility Reinforced Elastomer and Molecular-Machine Based Cement System

Abstract Long term wellbore integrity is crucial to produce a well for the entire life of the well. Cement sheath placed in annulus between casings and the formations experience high stresses under high temperature and high pressure which deteriorates mechanical properties of cement. This leads to formation of micro-cracks and fractures. Although several polymeric materials have employed to improve Young's modulus and tensile properties the cement, these additives have also adversely affected the compressive strength of the cement. Therefore, the additives that improve tensile properties, lower Young's modulus with minimum impact on compressive strength, a property known as toughness, is required to be developed for adequate long-term zonal isolation in severe oil well conditions. A synergistic combination of molecular machine-based technology and specially designed polymeric materials have resulted in producing superior cement composite with lower Young's modulus by more than 30%, higher Poisson's ratio, higher tensile strength without damaging the compressive strength a lot. Cement blends were cured at 300F under 3000 psi for 7 days. The set-cement samples were subjected to mechanical testing under temperature and pressure to study the elastic properties of the cement sheath. Molecular machine-based technology is first of its kind in terms of application in oil and gas industry that works like a molecular fiber with sliding rings. Synergistic combination of molecular machine-based technology and specially designed polymeric materials have improved the elastic properties of the cement without damaging compressive strength. Polymers used herein are stable in alkaline condition and thermally stable at least up to 250 °C. In the present study, the set-cement mixed with this additive are tested under repeated cycles of stresses under high pressure and temperature. The lowering of Young's modulus at different temperature and pressures clearly shows the effect of polymers. This is an excellent demonstration of molecular level chemistry uniformly distribute stresses exerted on the cement matrix to protect the set-cement from the formation of micro-cracks. The synergistic approach used herein is novel and the additives developed in this study have formed strong chemical bonds between additives and cement particles. This molecular binding of additives provide enhancement in elastic properties of the cement system.