V.A. Lensky, A.S. Zhuzhel’
Accuracy of a stratigraphic tie based on synthetic sonic and density logging
Key words: Tying reflections to stratigraphy; geoseismic model; synthetic trace; synthetic logging; Vertical Seismic Profiling.
For citation: Lensky V.A., Zhuzhel A.S. Accuracy of a stratigraphic tie based on synthetic sonic and density logging. Geologiya nefti i gaza. 2021;(4):103–111. DOI: 10.31087/0016-7894-2021-4-103-111. In Russ.
Using Vertical Seismic Profiling data allows solving all problems of tying reflections to stratigraphy in the most comprehensive manner. In order to achieve high-accuracy results of seismic acquisition, there must be a uniform grid of Vertical Seismic Profiling data covering the entire survey area. When Vertical Seismic Profiling data is limited or not available, reflections are tied to stratigraphy using synthetic traces computed from sonic and density gamma-gamma logging data. These data contain errors caused by mechanical destruction of borehole walls in the course of drilling and by a small radius of investigation, which may lead to unreliable geoseismic interpretation models. In the absence of real data, synthetic acoustic and density gamma ray logging data recovered from surveys of a different physical nature (electrical, nuclear) are used. During reconstruction, additional errors occur causing changes in amplitudes and shape of reflections, time and phase shifts of irregular character, and the relationship between synthetic traces and the real distribution of elastic properties of the section is lost.. A comparison with Vertical Seismic Profiling data shows that quality of synthetic sonic and density density gamma ray logging data is poor and they do not provide a wavefield close enough to the real one. The use of synthetic logs can lead to significant errors in stratigraphic control and reduce the accuracy of land seismic surveys.