The Application of an Improved Deconvolution Method Based on Mixed-Phase Wavelet Estimation for Thick Reservoir Connectivity Analysis

Abstract

Due to the low resolution and effective signal-noise ratio of the seismic data, the seismic reflection of the thick reservoir is weak or unsolvable on the seismic profile. There are two main reasons for this phenomenon: on the one hand, the thick reservoirs are not identified very well based on conventional seismic data with 90 ° phase shift. On the other hand is because of the influence of incorrect phase and amplitude information of wavelet. Thus the connectivity between wells of the thick sandbody is in contradiction with the dynamic results of the reservoir.

Extracting accurate wavelet from seismic records is one of the classic research topics of seismic digital processing. In this paper, based on the systematic analysis and summarization of the conventional mixed-phase wavelet extraction methods, the improved mixed-phase wavelet deconvolution technique in complex cepstrum domain for the thick reservoir connectivity analysis is presented.

This method uses the multi-trace statistical autocorrelation method to obtain the amplitude spectrum of the known wavelet, and then obtains a series of mixed-phase wavelets in the complex cepstrum domain. At the same time, according to the signal-noise ratio of seismic record, the desired output seismic wavelet is established. The ideal mixed-phase wavelet is determined by the deconvolution of the seismic variance norm and resolution. With the deterministic wavelet deconvolution it can improve the seismic effective signal. This technique eliminates the assumption of the minimum phase and has a significant effect in improving the seismic resolution.

Compared with the original seismic amplitude spectrum, the reflection energy of the processed seismic data is more balanced, and low-frequency components have a greater improvement. The internal energy of thick reservoir is strengthened, which greatly improves the degree of well-seismic matching of the thick reservoir in an oilfield in Bohai Bay. At the same time, the phenomenon of "no reflection on wells, weak energy between wells" appears on the seismic profile has also been significantly improved. Furthermore, the contradictions between dynamic and static data can be effectively resolved. The connectivity between wells by the newly processed data is closer to the tracer test results, which make a good explanation of the dynamic and static contradictions between development wells, and further demonstrated the reliability of the technology.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018