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 integ-ration algorithm and fluid-structure interaction mechanism of LS-DYNA,this study proposed a method for finite ele-ment 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 simula-tion results,this study analyzed the applicability of the two perforation techniques.Key findings of this study are as fol-lows:(1)Compared to the conventional perforation technique,self-cleaning and after-effect perforation techniques ex-hibit 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 per-formance.(3)For medium-porosity,low-permeability hydrocarbon reservoirs and those with low porosity and low per-meability,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 per-foration 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.
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