The staff of Autonomous Institution “V.I. Shpilman Research and Analytical Centre for the Rational Use of the Subsoil” actively participates in scientific and methodological research and innovative processes, including the creation and testing of new technologies for the geophysical data processing with help of data of various developing and testing data:
Obtained with the application of the high-performance technique of field vibroseismic works (slip-sweep). During contract work the specialists of the Centre together with colleagues from company «NOVATEK Research and Development Centre» developed and tested the technology of pre-correlation processing of vibration records (multi-zonal adaptive processing of vibrations) on the data of field trials for Trekhbugorny field and Zapadno-Solpatinskaya area (YNAO) in 2018-2019. Unlike the western methods of harmonic (technological) distortion suppression on vibration records based on the principle of their statistical subtraction from the original data, our technology is completely determined. Efficiency quantitative estimates of the application to vibration records were in the order of 25-30%, which is a major achievement in the field of vibroseismic data (see Fig. 1).
The principle of this technology is as follows:
- a decomposition of the primary vibration records into narrow frequency panels using band filtering on the principle of continuous seismic attenuation (spectrum width-average frequency ratio);
- a calculation and an application to each frequency panel of the upper and lower muting so that amplitude zeroing out of the field of the useful signal registration was provided;
- an optimal linear regular, random and quasi-random interference suppression in selected frequency panels;
- a correlation of vibration records with a correlation in frequency panels;
- an integration of correlated seismograms in frequency panels with the surface-coordinated actual frequency response and the desired frequency response.
Fig. 1. Comparative case study of time cross section fragments (Test Survey Crew-58/17 for Trekhbugorny field): a) an original cross section (flip-flop) without technological interferences, b) obtained from integral vibration records (the slip-sweep simulation) without multi-zonal adaptive processing of vibrations, c) a variant is obtained from integral vibration records (the slip-sweep simulation) after using technology of multi-zonal adaptive processing of vibrations. The arrows on the time cross section indicate the locations with the most intensive technological interferences.
conducted the electromagnetic reflection - common depth point method on one of the areas of the North of the Tyumen region.
testing of the analysis and the harmonization of the data obtained by the acoustic method and the data registered using the seismic sounding of electromagnetic waves using the program Seismic Balance as part of the software package OpenWorks Halliburton Landmark is completed.
Currently, the main field geophysical method of the oil and gas exploration is seismic reflection sounding - common depth point. The kinematic and dynamic characteristics of the waves reflected from the acoustic interfaces of the reservoirs provide information about the characteristics of the object under study (the formation, the traps), i.e. the depth of the deposit, the geometry, and, to some extent, the productivity prospects for oil and gas. However, the presence of hydrocarbons in the deep-saturating fluids does not create large contrasts in the elastic environmental parameters (unless, of course, there are large, unique oil and gas deposits), and therefore as well as in the formed wave field of the seismic reflection.
The advantage of the electromagnetic reflection - common depth point method inherited from georadiolocation is the high resolution of objects which contrast in electrophysical characterictics. This quality allows electromagnetic reflection method to identify, for example, hydrocarbons and water-saturated rocks even if they have similar densities, which is relevant both for hydrocarbon exploration and for monitoring of pollution with oil products. The algorithm for processing the initial electromagnetic wave records obtained by the electromagnetic reflection - common depth point method had a number of particular aspects of electromagnetic waves. The procedure identification algorithm is innovative for electromagnetic wave processing of the wave field.The basic computer processing cycle of electromagnetic waves using the seismic sounding of the common depth point is presented in Figure 2.
Fig. 2. Electromagnetic wave records of the common depth point before and after moveout adjustment at different processing stages
he registration interval at field trials is 10,000 ns, which corresponds to the depth of about 700 m. There is a velocity inversion with the depth (see Fig. 3 a, b), which is quite normal, since frozen earth is at the top of the cross section with electrophysical properties close to the dielectric. During processing, the measurement scale was changed by million times by equating 1 ms to 1 ns. The view of the wave field and spectra are quite usual to seismic acquisition specialists on this scale.
In the case of high-speed analysis carried out with seismic records, the parameterization of the moveout curves is actually carried out with Taylor-series hyperbolic approximation using the least square technique with second-order:where: Vогт - is the speed determined by the moveout curve.
The standard hyperbolic approximation of 100% had not produced the expected positive result when processing of the electromagnetic reflection - common depth point method.
Fig. 3. Results of the complex speed analysis for the electromagnetic reflection - common depth point method using different orders for the approximation of moveout curves for common depth point of electromagnetic waves
Whereas Taylor-series hyperbolic re-approximation using the fourth-order
where: l is the distance between the source and the receiver, VNMO notation is used for the second-order l parameter in time decomposition, as in the western literature;
Using of residual time-distance curve of CMP has greatly improved the situation. Moveout curves of electric waves became rectified.
Figure 4 presents a comparison of geophysical materials from acoustic and electromagnetic studies. The potential of the electromagnetic reflection - common depth point method as compared to seismic reflection sounding - common depth point method in the context of the resolution assessment and, as a result, the improvement in the quality of prospecting is clearly visible for a while at small study depths (up to 600-700 m).
Electromagnetic wave records of CSP
Seismic records of CSP
Fig. 4. Comparison of data resolution for electromagnetic and acoustic waves
The electromagnetic reflection - common depth point method (company «NOVATEK Research and Development Centre», company «TIMER») and the technology of electromagnetic wave processing (Autonomous Institution “V.I. Shpilman Research and Analytical Centre for the Rational Use of the Subsoil”) are one-of-a-kind unique research and production development and mean resolution increasing in comparison with acoustic data at least by 3 times.
Priorities for method developing:
- Production increase;
- Upgrading of the electromagnetic wave radiating source and receiving equipment;
- Testing the technology of multifold profiling (similar to seismic reflection sounding - common depth point method for seismic works) for the first time in world practice, using the electromagnetic waves at one of the KhMAO - Yugra field;
- Advanced processing technology of wave field for electromagnetic waves.
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