BRIGE: Characterizing the Rheological and Microstructural Evolution of Oil Well Cement Slurries under Elevated Temperature and Pressure Conditions

Background:

Insufficient zonal isolation, or sealing, is a prevalent issue in oil wells, from which many safety, economic, and environmental concerns can arise. And the origin of failure can be traced back to the placement of the fresh oil well cement slurry. During a critical period called transition time, the slurry is static and evolving from a near-Newtonian fluid to a viscoelastic solid due to the progression of cement hydration. If it does not either rapidly develop sufficient static gel strength or set, gas from adjacent geological formations will penetrate the material. This makes the slurry extremely susceptible to gas migration, which can result in permanent fluid channels in the well and compromise the sealing performance of the eventual cement sheath structure.

Technical Description:

The objective of the proposed work is to characterize the rheological properties of oil well cement slurries considered to be critical in achieving proper zonal isolation, namely gelation. This will entail measuring the dynamic flow properties under large and rapid deformation and the linear viscoelastic properties at rest. All rheological tests will be performed with rigorous attention to the effects of elevated temperatures and pressures to simulate down-hole conditions, and shear history to simulate different pumping conditions. The approach will be to implement complementary shear and extensional rheological techniques that place the sample under dynamic and quasi-static loading to monitor the evolution of rate of gelation and magnitude of static gel strength over the simulated cementing period. And an important complement to the rheology will be to monitor changes in the crystalline phases and pore network of the material, which will help provide insight into flow behavior and sealing performance. This will be done through synchrotron x-ray diffraction and x-ray tomographic microscopy for real-time, in-situ microstructural characterization.

Broader Signficance and Importance:

As a complex fluid that is continuously evolving, the thermomechanics and time- and shear-dependent flow behavior of fresh cement-based materials presents a challenging characterization problem. And the specific area of oil well cementing is a particularly good example of an application where understanding the fresh-state and early-age properties under severe conditions is critical. The proposed activities will improve understanding of the performance of oil well cement slurries during placement, which can help in the development of effective mix design methodologies and models. Ultimately, this can improve zonal isolation to increase production and safety, and reduce the negative environmental impact of oil well operations. Further, the experimental methodology proposed and developed in the study can potentially be extended to all types of cement-based systems for a wide array of applications.

Broadening Participation of Underrepresented Groups in Engineering:

An important component of the proposed work is the broadening participation plan, which will focus on supporting women in engineering through direct involvement in research activities at the pre-college, undergraduate, and graduate level. By engaging female students in the proposed research, the PI will present them with the opportunity to impact the field and subsequently give them the confidence and desire to pursue academia or advanced industry careers in engineering and science. And through various outreach programs coordinated by the Office of Outreach Programs and local chapter of Society of Women Engineers at Columbia University, the PI will participate as a guest speaker to present the proposed work and run hands-on lab demonstrations on rheology. This will serve as a means to convey the interdisciplinary nature of her field, invoke interest and recruit students. Further, the PI will encourage her own students to participate in outreach programs so that they, themselves, can go on to serve as role models. As a product of such programs herself, the PI firmly believes that such trickle down approaches are effective.

This research has been funded through the Broadening Participation Research Initiation Grants in Engineering solicitation, which is part of the Broadening Participation in Engineering Program of the Engineering Education and Centers Division.