Eco-friendly seismic survey in Khanty-Mansi Autonomous Okrug (KMAO)

Absolute elevation marks ranged from 40 to 260 m. The hydrographic network is formed by the Ural and Zazhivnaya rivers, which is a right tributary of the Ural River. The Ural River flows within the site in a sublatitudinal direction. The riverbed meanders strongly, forming numerous backwaters and lakes.

The research area is characterized by a well-developed infrastructure — a large number of power transmission lines, substations, gas pipelines (Orenburg-Soyuz, Orenburg-Novopskov), and highways are in operation.

A grader road runs through the entire work area, in fact the only one connecting the villages located on the work site with fairly active local vehicle traffic, starting in the morning and ending at night.

To receive reflected waves, low-frequency point seismic receivers were used, allowing the signal to be recorded with its original frequency response without distortion in the low-frequency range.

The survey geometry implied a full-azimuth centrally symmetrical observation system with an active array aspect ratio of 1×1 or close to this value. In addition to high requirements for the source for generating SVIP signals from the lowest frequencies, which implies a high load on the systems and units of the vibration installation while maintaining acceptable values ​​of the test parameters, such methods are sensitive to interference of natural and man-made origin. This approach made it possible to use more modern technologies and algorithms to determine the kinematic characteristics of the upper and middle parts of the section, which provides a significant advantage compared to previously used approaches.

Full-wave inversion (FWI) on refracted waves was used. Seismic material from such modern methods has made it possible to significantly improve the quality of noise suppression procedures and 5D regularization algorithms and to refine the GPS based on reflected waves.

The main source of excitation was a vibroseis, represented by a UVSS Nomad-65 (Sercel); additionally, for exclusive populated areas, an explosive source was used in the form of groups of shallow wells, drilled with the help of a KMB2-10M motor drill.

The study of the upper part of the section was carried out by a combination of two methods with signal excitation by means of the Yenisei KEM-4 source, produced at the Impulse plant:

— direct microseismic logging in the amount of 105 wells and a depth of up to 140 m,

— ZMS-MPV in the amount of 1850 soundings.

The full-azimuth active array implemented on the project provided a reception aperture of 12×12 km and allowed for a uniform distribution of seismic attributes in the survey bins.

The active array included 9,600 seismic channels (40 LP by 240 PP) with maximum offsets of 8,450 m. This reception aperture required colossal efforts from the seismic crew to maintain only the active array with an area of ​​144 km² in working order. The total permanently supported working arrangement on average amounted to an area of ​​225 km², which is comparable to the area of ​​the entire city of Orenburg — 259 km² .

Analysis of the quality of seismic material showed the possibility of suppressing noise by trivial processing procedures, without damaging the amplitude-frequency component of the useful signal.

During the successful implementation of the project in the Orenburg region, volumetric seismic exploration work of a modern technological level was carried out with the excitation and registration of a low-frequency broadband SWIPS signal.

The obtained results of the analysis of the quality of seismic data indicate successful and stable registration, including low-frequency components of the useful signal, which will have a positive effect on the subsequent implementation of FWI on refracted waves.