Energy absorption performance has been a long-pursued research topic in designing desired materials and structures subject to external dynamic loading. Inspired by natural bio-structures, herein, we develop both numerical and theoretical models to analyze the energy absorption behaviors of Weaire, Floret, and Kagome-shaped thin-walled structures. We demonstrate that these bio-inspired structures possess superior energy absorption capabilities compared to the traditional thin-walled structures, with the specific energy absorption about 44% higher than the traditional honeycomb. The developed mechanical model captures the fundamental characteristics of the bio-inspired honeycomb, and the mean crushing force in all three structures is accurately predicted. Results indicate that although the basic energy absorption and deformation mode remain the same, varied geometry design and the corresponding material distribution can further boost the energy absorption of the structure, providing a much broader design space for the next-generation impact energy absorption structures and systems.

Summary The leakage of reservoir fluids into a wellbore during perforation, workover, or other completion operations is a substantial concern, especially in high-temperature wells where existing fluids used to mitigate reservoir-fluid influx offer poor performance. To maintain the hydrostatic integrity of the wellbore during these operations, a thermally stable, solids-free fluid-loss pill has been developed. The pill is composed of synthetic polymers and crosslinkers in monovalent high-density brine. Under ambient-pressure and -temperature conditions, the pill flows as a viscous liquid and remains fluid for more than 6 months. Upon exposure to elevated temperatures (200 to 375°F), the pill crosslinks to form a robust gel that can act as an appropriately weighted, low-fluid-loss pill. This pill can temporarily seal the reservoir, enabling well control during completion operations. Gelled samples of the fluid-loss pill have maintained integrity for up to 3 weeks under high-pressure/high-temperature (HP/HT) conditions in laboratory testing, with minimal signs of collapse. The gel can be readily destroyed with an oxidative breaker providing a substantial reduction in viscosity. At the end of the completion process, the timing of gel removal is completely controlled by the timing of the breaker addition. In addition to gel-stability tests, formation damage caused by the gel and the fluid loss of the pill were assessed by coreflooding experiments by use of Berea core plugs. Average fluid loss over 3 days at 320°F was approximately 50 cm3. Restoration of the Berea core permeability after the treatment exceeded 85% of the initial permeability, with low lift-off pressures observed. This paper presents full laboratory data on the development of the thermally stable, solids-free fluid-loss pill, including gel-stability, fluid-loss, and breaker testing.

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The leakage of reservoir fluids into a wellbore during perforation, workover, or other completion operations is a substantial concern, especially in high temperature wells where existing fluids utilized to mitigate reservoir fluid influx offer poor performance. To maintain the hydrostatic integrity of the wellbore during these operations, a thermally-stable, solids-free fluid loss pill has been developed.The pill is composed of synthetic polymers and cross-linkers in monovalent high-density brine. Under ambient pressure and temperature conditions, the pill flows as a viscous liquid and remains fluid for over six months. Upon exposure to elevated temperatures (200˚F to 375˚F), the pill cross-links to form a robust gel that can act as an appropriately-weighted, low fluid loss pill. This pill can temporarily seal the reservoir, enabling well control during completion operations.Gelled samples of the fluid loss pill have maintained integrity for up to three weeks under HTHP conditions in laboratory testing with minimal signs of collapse. The gel can be readily destroyed with an oxidative breaker providing a substantial reduction in viscosity. At the end of the completion process, the timing of gel removal is completely controlled by the timing of the breaker addition.In addition to gel stability tests, formation damage caused by the gel and the fluid loss of the pill were assessed by core flooding experiments using Berea core plugs. Average fluid loss over 3 days at 320 °F was about 50 mL. Restoration of the Berea core permeability after the treatment exceeded 85% of the initial permeability with low lift-off pressures observed. This paper presents full laboratory data on the development of the thermally-stable, solids-free fluid loss pill including gel stability, fluid loss, and breaker testing.

No abstract