Dynamic simulations and applicability evaluation of novel perforation techniques

The development and improvement of perforated completion techniques hold great practical significance and value for efficient testing and exploitation of oil and gas fields. However, conventional shaped-charge perforation for well completion of low-permeability reservoirs (e.g., low-permeability coal seams) suffered high seepage resistance and reduced productivity due to the presence of compaction damage zones. To achieve enhanced exploitation efficiency of low-permeability reservoirs, novel perforation techniques, including self-cleaning and after-effect perforation, have been proposed. However, their perforation performance and applicability remain ambiguous. Based on the explicit time integration algorithm and fluid-structure interaction mechanism of LS-DYNA, this study proposed a method for finite element modeling of dynamic perforation simulations involving strata, cement sheaths, casings, and perforation charges. For self-cleaning and after-effect perforation techniques, this study developed a dynamic numerical simulation scheme, constructed finite element simulation models, and conducted dynamic simulations. Finally, based on numerical simulation results, this study analyzed the applicability of the two perforation techniques. Key findings of this study are as follows: (1) Compared to the conventional perforation technique, self-cleaning and after-effect perforation techniques exhibit decreased perforation depths but enlarged perforation diameters, which increased by approximately 15%. (2) The perforation depth and diameter were inversely proportional to compressive strength, elastic modulus, confining pressure, and directly proportional to porosity. Meanwhile, negative pressures posed minor effects on individual perforation performance. (3) For medium-porosity, low-permeability hydrocarbon reservoirs and those with low porosity and low permeability, self-cleaning and after effect perforation techniques increased the perforation channel volume by about 9.55% and 12.23%, respectively compared to conventional perforation, suggesting outstanding perforation performance. The findings of this study will provide theoretical support for the design and application of self-cleaning and after effect perforation techniques, thus holding great significance for the development of both techniques and their application to low-permeability reservoirs (e.g., low-permeability coal seams) for production growth of oil and gas wells.