Publications

Results 1–25 of 165
Skip to search filters

Advanced Detection of Wellbore Failure for Safe and Secure Utilization of Subsurface Infrastructure

Matteo, Edward N.; Conley, Donald M.; Verzi, Stephen J.; Roberts, Barry L.; Doyle, Casey L.; Sobolik, Steven R.; Gilletly, Samuel G.; Bauer, Stephen J.; Pyrak-Nolte, L.P.; Reda Taha, M.M.; Stormont, J.C.; Crandall, D.C.; Moriarty, Dylan; John, Esther W.; Wilson, Jennifer E.; Bettin, Giorgia B.; Hogancamp, Joshua H.; Fernandez, S.G.; Anwar, I.A.; Abdellatef, M.A.; Murcia, D.H.; Bland, J.B.

The main goal of this project was to create a state-of-the-art predictive capability that screens and identifies wellbores that are at the highest risk of catastrophic failure. This capability is critical to a host of subsurface applications, including gas storage, hydrocarbon extraction and storage, geothermal energy development, and waste disposal, which depend on seal integrity to meet U.S. energy demands in a safe and secure manner. In addition to the screening tool, this project also developed several other supporting capabilities to help understand fundamental processes involved in wellbore failure. This included novel experimental methods to characterize permeability and porosity evolution during compressive failure of cement, as well as methods and capabilities for understanding two-phase flow in damaged wellbore systems, and novel fracture-resistant cements made from recycled fibers.

More Details
TYPE SAND Report YEAR 2021
OSTIDOI

Modelling yield cap evolution in sandstone based on brittle creep experiments

International Journal of Rock Mechanics and Mining Sciences

Choens, R.C.; Bauer, Stephen J.; Shalev, E.; Lyakhovsky, V.

The Zenifim Formation is being considered as a potential disposal formation for a deep borehole nuclear repository concept in Israel. Site selection and repository construction are intended to ensure that waste is separated from circulating groundwater, but long-term deformation of the wellbore could potentially create fluid flow pathways. To understand how time-dependent rock strength could affect wellbore stability, we conducted creep tests under low to moderate confining pressures on retrieved core from the Zenifim formation. During creep, samples strain slowly as gradual damage accumulation progressively weakens the samples. Failure eventually occurred through the near-instantaneous formation of a shear fracture. Experimental results were used to calibrate a continuum damage poro-elastic model for sandstones. The calibrated damage-poro-elastic model successfully simulates different types of loading experiments including quasi-static and creep. The state of strain in experiments is close to yield during loading as the yield cap continuously evolves with damage accumulation. For creep tests, most damage occurs during triaxial loading. Minor damage accumulation occurs under constant load until the final stage of creep, where damage accelerates and promotes unstable fracturing.

More Details
TYPE Journal Article YEAR 2021
ScopusOSTIDOI

Mechanical Response of Castlegate Sandstone under Hydrostatic Cyclic Loading

Geofluids

Kibikas, William M.; Bauer, Stephen J.

The stress history of rocks in the subsurface affects their mechanical and petrophysical properties. Rocks can often experience repeated cycles of loading and unloading due to fluid pressure fluctuations, which will lead to different mechanical behavior from static conditions. This is of importance for several geophysical and industrial applications, for example, wastewater injection and reservoir storage wells, which generate repeated stress perturbations. Laboratory experiments were conducted with Castlegate sandstone to observe the effects of different cyclic pressure loading conditions on a common reservoir analogue. Each sample was hydrostatically loaded in a triaxial cell to a low effective confining pressure, and either pore pressure or confining pressure was cycled at different rates over the course of a few weeks. Fluid permeability was measured during initial loading and periodically between stress cycles. Samples that undergo cyclic loading experience significantly more inelastic (nonrecoverable) strain compared to samples tested without cyclic hydrostatic loading. Permeability decreases rapidly for all tests during the first few days of testing, but the decrease and variability of permeability after this depend upon the loading conditions of each test. Cycling conditions do affect the mechanical behavior; the elastic moduli decrease with the increasing loading rate and stress cycling. The degree of volumetric strain induced by stress cycles is the major control on permeability change in the sandstones, with less compaction leading to more variation from measurement to measurement. The data indicate that cyclic loading degrades permeability and porosity more than static conditions over a similar period, but the petrophysical properties are dictated more by the hydrostatic loading rate rather than the total length of time stress cycling is imposed.

More Details
TYPE Journal Article YEAR 2021
ScopusOSTIDOI
Results 1–25 of 165
Results 1–25 of 165