Mechanism (biology)

Quantum mechanics

Filtration (mathematics)

Drilling

Engineering

Nanoparticle

Statistics

Geotechnical engineering

Metallurgy

Materials science

Bentonite

Mineralogy

Petroleum engineering

Filter cake

Chemical engineering

Clay minerals

Geology

Oceanography

Waste management

Mechanical engineering

Physics

Drilling fluid

Nanotechnology

Mathematics

Environmental science

Particle (ecology)

Zeta potential

Composite material

Rheology

Chemistry

Agglomerate

Chemical Engineering Journal

• High temperature-induced failure mechanism in drilling fluid was investigated. • High temperature reduces aluminum and hydroxyl species on clay surface. • High temperature reduces negative electricity of bentonite and its hydrophilicity. • Size of bentonite increases, and as-formed filter cake was thicker and looser. • After disrupture of layered structure, the particles of bentonite agglomerate. Designing ultrahigh-temperature water-based drilling fluid for an ultra-deep well is a long-standing critical technical problem. Unraveling the failure mechanism of clay in the drilling fluid at ultrahigh temperatures harbors tremendous scientific and industrial significance. Herein, the high-temperature failure mechanism was elucidated by molecular dynamics (MD) simulation, the multi-characterizations (e.g., XPS, Zeta potential, XRD, SEM, Contact angle, and FT-IR) together with the rheology and filtration experiments. It was found that high temperature could destroy the layered structure of clay in the drilling fluid, leading to reduction of aluminum element and hydroxyl species on its surface, thus reducing the amount of negative electricity of clay and its hydrophilicity. As a result, the size of the clay particle in the drilling fluid increased, and the as-formed filter cake was thicker and looser. Furthermore, the rheology and fluid loss performance of the drilling fluid degraded or disrupted. When the temperature increased from 25 to 200 °C, the amount of hydroxyl group on the surface of the clay reduced by 45%. Moreover, the median size of clay particles increased by 2.7 times and the fluid loss increased by 1.6 times. The insights and methodology reported here shed new light on the fundamental understanding of failure mechanism in drilling fluid and may pave the way for improving the efficiency of drilling fluid at high temperature.

Insights into the high temperature-induced failure mechanism of bentonite in drilling fluid