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The Temperature Dependence of Sandstone Compaction
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 81st EAGE Conference and Exhibition 2019, Jun 2019, Volume 2019, p.1 - 5
Abstract
We have studied the effect of elevated temperatures (up to 150°C) on sandstone deformation, with a focus on the brittle-ductile transition and the ductile regime. This was executed through triaxial deformation experiments, performed at a range of effective pressures on fluid saturated cores of sandstone. Samples were deformed at room temperature or at elevated temperatures under either constant strain rate (10-5 s-¹) or constant stress (creep) conditions.
Constant strain rate tests in the ductile regime show that at 150°C the differential stress required for the onset of compaction is reduced by 10-20 MPa, with the exact amount being a function of sandstone composition and the effective pressure. The pressure of the brittle-ductile transition is also reduced by the temperature increase.
During constant stress tests, which run for a few days to a few weeks, samples are initially loaded at a constant strain rate, before being held at a set stress value. The strain rate at which the sandstone continues to deform decreases with increasing time and can reach rates as low as 10-8 s-¹. At 150°C the sandstone underwent compactant creep at similar strain rates to its room temperature counterpart, but with a differential stress reduction of 20–30 MPa.