Shaped Charge Particle Jet Penetration in Limestone

Oil well perforators typically consist of shaped charges that use powdered metal liners to form high-velocity particle jets. Although the physics of jet penetration is well established for solid materials, the particle jet poses computational challenges. We report on the development of a particle-scale model of a jet penetrating a limestone (CaCO3) target. The particles vary in size (1--500 microns) and consist of one or more materials (e.g., tungsten or copper). Interparticle spacing is adjusted to match the apparent jet density (experimentally determined from flash X-ray images of powdered metal jets). The limestone target is 100{\%} calcite, with log-normal size distribution of circular voids randomly distributed throughout the matrix. Voids can be empty or filled with fluid, such as brine or hydrocarbons. At low-impact velocities, the strength of the particles and calcite matrix strongly influences penetration depth, tunnel diameter, and other tunnel features. At higher velocities, strength is less important; density and compressibility become the dominant parameters. Results of particle-scale simulations are compared with continuum calculations of multimaterial porous jets with bulk-averaged properties. The continuum models perform reasonably well under certain conditions, although some discrepancies between model results exist. Particle-scale simulations are being investigated as a means to parameterize the continuum models for full-scale simulations of oil well perforators.$^{\mathrm{ \newline }}$