Modern development of shaped charges has resulted in greater and greater explosive loads on the perforating guns and has stretched the capacity of perforating guns into uncharted territory. Traditional gun design approaches and standards use collapse pressure calculation and swell measurement with overloaded charges as design verification methods. The extremely complicated interactions between explosives, fragmented casings, and the gun wall are evaluated on an empirical basis, and the nature of these interactions is not well understood. In this paper, we present a new design model that augments traditional design approaches and provides gun designers with better data on gun system structural performance including the effects of phasing, shot density, and charge type.
The loads imposed on the gun body by the explosives are multi-dimensional due to the spiral arrangement of most shaped charges. The resulting dynamic response of the gun body is therefore quite complex and requires three-dimensional analysis. High-frequency bending, torsion, and tensile loads are expected. The casings are typically fragmented, and some of the larger fragments can impose large impact loads on the gun wall. A fully-coupled computer model has been developed that incorporates the rapid explosion, casing fragmentation, and multi-dimensional structural responses.
Multiple instrumented surface tests were carried out to validate the dynamic three-dimensional model. Proprietary testing techniques were used to extract gun internal pressure history and gun stress history at multiple locations immediately following detonation. Redundant strain gages were used and shots were repeated to ensure the integrity of the data.
This paper first presents the newly developed three-dimensional simulation model in full details. The second section describes the instrumented gun test set up and results. The final section of this paper presents validation of the model through comparison with test data.
