DOI: 10.5880/fidgeo.2019.005
title: Compaction creep data uniaxial compaction of quartz sand in various chemical environments

description: We studied the effect of pore fluid chemistry on compaction creep in quartz sand aggregates, as an analogue for clean, highly porous, quartz-rich reservoir sands and sandstone. Creep is specifically addressed, because it is not yet well understood and can potentially cause reservoir compaction even after production has ceased. Going beyond previous work, we focused on fluids typically considered for pressure maintenance or for permanent storage, e.g. water, wastewater, CO2 and N2, as well as agents, such as AlCl3, a quartz dissolution inhibitor, and scaling inhibitors used in water treatment facilities and geothermal energy production. Uniaxial (oedometer) compaction experiments were performed on cylindrical sand samples at constant effective stress (35 MPa) and constant temperature (80 °C), simulating typical reservoir depths of 2-4 km. Insight into the deformation mechanisms operating at the grain scale was obtained via acoustic emission (AE) counting, and by means of microstructural study and grain size analysis applied before and after individual compaction tests.
description: Data logging and output:The present data was obtained using an Instron loading frame employed with a uniaxial (oedometer) compaction vessel located in the HPT laboratory at Utrecht University. A complete description of the machine is provided by Schimmel et al., (2019). Mechanical and acoustic emission (AE) data were recorded at 1 Hz using National Instrument (NI) VI Logger software, an overview is presented in Table 1. Table 1. Overview of recorded data Name Unit Description Row - - Instron load V Load externally measured by the Instron loading frame Instron position V Position of the Instron loading ramp measured by the Instron LVDT Local load V Load internally measured by the local load cell Local position V Position of the top measured by the local LVDT Temperature V Sample temperature measured close to the sample Count A - Number of AE counts from counter A Count B - Number of AE counts from counter B Data processingAll measured quantities were converted to realistic units using the following conversions: - Time [s] = row * 1 - Instron load [kN]= Instron load [V] * 10 - Instron position [mm] = Instron position [V] * 5 - Local load [kN] = local load [V] * 33.3 - Local position [mm]= local position [V] * -0.100684133 - Temperature [°C] = temperature [V] * 100 The displacement data were calculated from the Instron and local position, which were corrected for apparatus distortion and thermal expansion using calibrations carried out in an empty vessel at pressure and temperature conditions covering the present experiments. The displacement data (D) were corrected according to Dsample = Dtotal – D¬distortion Where D¬distortion = 1.126e-09 * x8 - 7.744e-08 * x7 + 2.059e-06 * x6 - 2.5e-05 * x5 + 9.109e-05 * x4 + 0.0009916 * x3 - 0.01238 * x2 + 0.066 * x And is x is the applied load (Instron load). Microstructural dataGrain size analysis was performed on one undeformed and several deformed samples using a Malvern laser diffraction particle sizer. This allowed determination of the average grain size and grain size distribution before and after deformation. Laser particle size analysis systematically overestimates grain size by approximately 25 %, due to fines adhering to coarse grains. Stitched micrographs are given for one sample that was only pre-compacted and several samples that were allowed to creep after pre-compaction. Portions of these micrographs were used for crack density analysis.