This paper illustrates the challenges in designing carbon dioxide (CO2) injection on a triple porosity reservoir with partial/limited data for reservoir & fluid characterization. Conductive faults coupled with unfavorable miscibility conditions add significant complexity to an already challenging system. Developing predictive finite-difference reservoir simulation models incorporating complex recovery physics to design CO2Enhanced oil recovery (CO2EOR) implementation, including a CO2Pilot design, was the scope of this project. This paper outlines the comprehensive design for a full cycle CO2 development, culminating in an ongoing CO2 field pilot. We start reviewing reservoir performance, heterogeneity, and existing characterization of the reservoir complex, including the presence of different porosity types and its impact on CO2 injection performance. Insights gained from digital-physical core experiments provided significant input on conceptualization of the recovery system in the vuggy environment. A selection process was then done to determine the optimal numerical representation of triple porosity within an otherwise dual or composite finite-difference formulation, focusing on the impact on the field injection. It concludes with the results of an on-going CO2 injection pilot specifically designed to address the remaining challenges of the injection.
Due to the interactions between the fillers, the polymer and the die, the printing of filled polymer composites using the material extrusion process is challenging. Numerical computations have been carried out to investigate the fluid dynamics and heat transfer within the hot end of the material extrusion process. Firstly, a standard nozzle equipping the majority of 3D printers is considered. However, it is not possible to print an object on a commercial printer with a composite made of polylactic acid with 20wt% of carbon black due to clogging issues. This impossibility is supported by the application of the Q-criterion, which is an indicator of flow kinematics. As a result, a novel nozzle design is proposed. The printing of the same object on the same printer equipped with the new nozzle succeeds. The electrical properties of walls printed with both the standard and the new nozzles are evaluated. The conductivity of a wall printed with the new nozzle is 42% higher than that of a wall printed with the standard nozzle. Furthermore, complementary analysis using scanning electron microscopy shows that the porosity of the walls printed with the new nozzle is reduced which is a promising improvement.
The melting of an amorphous polymer filament through the hot end of a material extrusion process is addressed using computational multiphase fluid dynamics coupled to heat transfer. Only the flow through the heat block is investigated. The air gap between the filament and the interior of the extruder is accounted for. The polymer/air interface is implicitly tracked by a level-set method. The system of equations is solved using a finite element method with a time-marching method. Three extrusion velocities are investigated. For the lowest velocity, after the contact of the polymer with the extruder on the nozzle, the air gap disappears with time. The transient regime lasts a few tens of seconds. For the two larger velocities, even if the air gap is more and more reduced with time, it persists for a long time. The extension of the air gap increases with the velocity. The feeding force needed to push the filament is obtained by the integration of the tension on the surface of the extruder. After a transient regime driven by the heat transfer, a steady-state regime is observed for the three velocities. Roughly, the feeding force increases linearly with the extrusion velocity. A good agreement is found with experimental results for the two smallest velocities.
Additive manufacturing processes and especially the family of laser powder bed fusion technologies have a great industrial potential since it enables, from metal powder beds, to produce full density complex monolithic parts. The high-temperature gradient resulting from the locally concentrated energy input leads to strong temperature fields driving non-negligible residual stress gradients, part deformations and crack formation. Resulting stress and texture gradients arise from the interdependent physical phenomena (metallurgical, thermal, mechanical and fluid mechanics) occurring during the process. Present work focuses on the residual stress being built in an austenitic stainless steel cubical shaped part of 1 cm side, prepared by a laser powder bed fusion process from a gas-atomized metallic powder (from martensitic X40CrMoVN16-2 stainless steel), through a full residual stress tensor mapping achieved thanks to neutron diffraction. Stress analyses incorporate morphological and crystallographic textures, as well as elastic anisotropy. Components of the principal stress tensor display compressive values close to the baseplate that develop into low compression, and a tensile stress state at the subsurface (surrounding thermal history effects). Results also underline the strong impact of matter environment (and thus thermal environment) onto stress gradient magnitude and the complex loading origins of the residual stress.
