A hybrid FWI-JMI for high resolution velocity estimation

P-waves is scattered due to high impedance contrast between the gas-filled formations with its surrounding, generating complex travel paths which often result in low frequency and low amplitude appearance-deteriorated image. CRP picks become unreliable thus affecting the estimation of the velocity by ray-based method. FWI which uses two way wave equation, is a powerful tool for high-resolution velocity estimation. However the use of diving waves FWI often limit the depth of investigation to one third of the maximum offset only while reflection FWI algorithms neglect density as a parameter and use only velocity to describe the observed measurements. JMI is another method developed for velocity estimation. In JMI, seismic reflections are forward modeled by scattering and propagation operators instead of detailed velocity and density models. The ability of JMI to take advantage of the higher-order scattering allows for a more accurate estimation of the velocity especially in low illuminated areas such as underneath the gas clouds. However, the use of one way wave equation makes JMI less superior to FWI. Both methods actually complement each other. This paper will review the implementation of “hybrid FWI-JMI” which could be the best tool for velocity model estimation in shallow gas affected area.