Study On Energy Gathering Characteristics Of Impulsive Sound Source And Detection Of Cracks Near Open Hole

As the current resource exploration direction gradually develops towards unconventional oil and gas resources,more accurate geological structure and reservoir distribution information need to be obtained,single well sound wave depth detection technology is particularly important as an effective means to detect the geological structure near the well.The sound sources used in the traditional single well sound wave depth detection technology are mainly monopole sound sources and dipole sound sources,their detection depth is limited and the radiation directivity is not strong,in order to solve these problems,the impulse sound source is introduced into the single well sound wave depth detection technology,the energy gathering device is used to charge the impulsive sound source to enhance the effective energy of the sound source radiating out of the well and improve the detection capability of the single well sound depth detection technology.Firstly,the paper introduces the basic generation mechanism,working process,experimental system and simulated sound source function of impulse sound source;Secondly,the application situation,advantages and disadvantages of the three common energy gathering methods are analyzed,and the parabolic energy gathering method is selected for the impulsive sound source,and through the finite element COMSOL software,the impulsive sound source is used to simulate the underground parabolic surface energy gathering characteristics,the two dominant frequencies of the impulsive sound source after energy gathering,3kHz and 7kHz,are determined,which can be used as the sound source excitation frequency for deep exploration and well-side crack detection,at the same time,the effect of the energy accumulation effect of the impulsive sound source in different well diameters and different formation media was studied,and verified the radiation directivity and deep detection ability of the impulsive sound source after energy gathering;Finally,an impulsive sound source with an excitation frequency of 7 kHz is used to detect the fractures near the well and the fractures that intersect the wellbore to verify the influence of parabolic energy gathering on the sound wave energy during fracture detection.Through simulation,it can be known that the sound source can greatly improve the radiated energy and directivity of the sound wave after energy gathering,which provides a powerful help for the subsequent deep exploration and the use of the sound wave information to retrieve the formation information.