AGGREGATE ROCK TYPING: STATE OF THE ART

Sand, gravel, and crushed rock are vital feedstocks for our modern society. They are used to build critical infrastructure like roads, bridges, airports, dams, and buildings. Despite their vital place in our economy, many urban areas are rapidly consuming local sources of these materials and are being forced to either transport these materials, or invest in underground mines. Investment decisions to support the increased cost of these operations will require advanced geological characterization to ensure materials with high “aggregate quality” are present in sufficient quantities. “Rock typing” is a common workflow in the petroleum industry for categorizing rocks by their depositional, diagenetic, and petrophysical properties for the purposes of 3D geologic models of subsurface reservoirs. These models are then handed off to engineers who can simulate well placement and design the most efficient field development plans to maximize economic recovery of hydrocarbons. This same playbook can be applied to mining construction coarse and fine aggregates. Fundamentally, both endeavors require both a knowledge of the favorable rock properties (high porosity, high permeability, and low water saturation for petroleum reservoirs; low microporosity, low clay content, and pure mineralogy for carbonate coarse aggregates) as well as how those properties correlate to geological rock types (that is, depositional and diagenetic facies). While petroleum geologists can only visit a reservoir “through the borehole”, quarry geologists can build much more sophisticated stratigraphic models of deposits as they are produced by incorporating geologic descriptions and property measurements. In the petroleum industry, this style of comprehensive geological characterization and property modeling has been shown not only show <where> favorable deposits are, but also <why> they are there. This knowledge reduces uncertainty in resource assessments, streamlines production, and identifies favorable trends for future exploration.