Identification of lithological characteristics on glacial sediments using a micromechanics approach

Abstract

Abstract To identify the lithology present along the 1138 m length of the AND-2A drillcore; compressional wave velocity Vp and wet bulk density ρWBD data sets acquired on the drillcore are portrayed on density-velocity Rock Physics Templates (RPTs) constructed using a Self-Consistent (SC) micromechanics approach. The three most abundant minerals present in the drillcore— quartz, calcite, and mixed clays —as well as the pore fluid (brine), served as the initial values for the SC model. Results are then compared with the lithology that is identified using Gardner density-velocity cross plots. Thus, the principal lithologies found in the AND-2A drillcore have already been mentioned in the scientific works, and results from both the Gardner and SC approaches show a good correlation with these lithological features. When compared to the lithology of six specific rock specimens that were acquired at various depths along the AND-2A drillcore, our findings likewise match up well. These findings imply that the suggested SC technique may be useful for identifying lithology in boreholes where downhole physical characteristics could exist during intervals when the drillcore was not recovered in whole. Additionally, the SC approach is helpful even when physical properties are derived from measurements because lithology can occasionally be problematic to estimate from visual examination alone, and supplementary evidence from the evaluation of the physical properties could offer further understanding.