oa Stages of Formation Seismic Ray Tomography as a Method of Studying the Subsurface in Oil and Gas Industry. Modern Modifications

Over the past twenty years, 3D seismic ray tracing has evolved from a research tool to a more operational tool because of increasing interest in the petroleum industry. During the last few decades, inversion (tomographic) modeling has largely replaced the bulky forward algorithm as a faster and more efficient tool for determining the distribution of seismic velocities, due to several disadvantages of the forward method. The process of manual model fitting, performed for multiple blast points simultaneously, is difficult and time-consuming, especially compared to inverse automatic methods.

The modern modification of the inverse ray tracing problem solution is seismic reflection tomography. It deals with the analysis of curved rays that are reflected and refracted inside the Earth. In reflection tomography, space is divided into cells, each having a certain velocity and reflectivity. The final model is the one whose velocities and reflectivities best describe the data.

The history of the formation of seismic ray tomography as a method of studying the Earth’s interior begins with the study of earthquakes as sources of seismic waves that are registered by seismometers. This technique turned out to be quite effective because it allowed distinguishing the mantle and the core. After this research seismic tomography became a method of geophysical research. The further development of seismic tomography contributed to interest in its use as a tool for obtaining additional information on the structure of deposits. Further development of tomography was timed to solve the problem of lack of ambiguity between reflection depth and reflected waves velocity ( turned-ray tomography, SMART method, using B-spline representation and etc.).

Analysed algorithms bring about a conclusion that the 3D reflection tomography described in this paper has proven to be efficient for a geologic synthetic structure.