Automated method for determination of geological horizons nonconformity according to three-dimensional seismic data

• Дата: 2019
• Автор: Gryn’, D. M.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: Subbotin Institute of Geophysics of the NAS of Ukraine 2019
• Теми: seismic; fault; fissure; thrust-fault; wavelet analysis; logarithmic decrement of absorption
• Онлайн доступ: https://journals.uran.ua/geofizicheskiy/article/view/190075
• Назва журналу: Geofizicheskiy Zhurnal

In complicated geological media mapping of faults according to wave seismic field often becomes difficult. In algorithm of preliminary processing of seismic data spatial summation of traces is present that leads to «corrosion» of exact location of the fault. Automated method is proposed for identification of faults in three-dimensional body of seismic data of logarithmic decrements of fading (LDF) obtained solving of inverse problem of seismic. Resolvability of LDF data is comparable with resolving ability of initial seismic records.As a result, the analysis is conducted not only taking into account reflecting features of the medium but also with its absorbing properties.Abrupt change of absorption in minor spatial interval is a good identifying attribute of the presence of non-conformable lean-vertical occurrence of geological horizons. Deep and spatial distribution of identified fault structures is an additional argument supporting their existence.We used as an example the materials of detailed seismic mapping of МОГТ 3D conducted by «Ukrgeophysisc» in thin-layer mining field of «Krasnolimanskaya» mine. Geological section of this area is specific by its complexity because of the presence of thrust-shear geological structures related to tension and subsequent compression of these territories that lead to appearance of large amount of deep faults and local fissures.In consolidated geological medium gradient of change of logarithmic gradient of fading will become minor and function of absorption mainly consists of low-speed harmonics. The presence of shear faults leads whereas to abrupt change of absorbing properties of the medium and to appearance of local high-speed oscillations.  It is possible to find out the presence of such low-amplitude non-stationary processes in harmonic functions using wavelet analysis. Therefore the paper presents a method that makes possible to find out fault-related decompaction zones in three-dimensional data 3D CDP of the mine field «Krasnolimanskaya 5,25 km2 consisting of almost 27,5 million values reflecting different physical properties of the medium.