Simulation Miscellaneous

Modelling the Dynamics of Well Perforation

One of the crucial steps in the completion of many oil wells is their perforation, required to establish communication with the target reservoir. Perforation is a very short duration, high energy event in which a series of explosive shaped charges is fired to produce corresponding perforations into the hydrocarbon-bearing formation. This event gives rise to violent pressure and structural dynamics that die out within a second or two, depending on the specific completion design. During this time, the nature of the pressure dynamics and resulting fluid response determine the initial quality of the communication between the well and the formation, which has significant consequences for the overall productivity over the well’s lifetime, as well as the integrity of the tool string components during the perforation event.

Developments in *MAT_WINFRITH_CONCRETE and Application to Modelling of Segmented Concrete Tunnel Linings

Tunnels constructed by Tunnel Boring Machines are lined with precast reinforced concrete segments. The joints between the segments must resist a combination of compressive load and bending moments induced by non-uniform pressure from the soil. Failure modes to be considered during design include splitting of the joint face under concentrated compressive load, spalling of the exterior or interior faces of the segments under bending actions, and impacts of bolt connection details on the stability of the joints. The capacity of the segments to resist such failures may be explored in detail using LS-DYNA’s nonlinear concrete models. The paper includes examples from an investigation into a tunnel that partially collapsed shortly after construction. The failure modes revealed by the site investigation of the collapsed tunnel matched well with those shown by the model.