Sains Malaysiana 46(11)(2017): 2169-2177

http://dx.doi.org/10.17576/jsm-2017-4611-18

The Synthesis and Decomposition of Signals and its Application in Subei Basin Exploration

(Sintesis dan Penguraian Isyarat serta Aplikasinya dalam Penerokaan Lembangan Subei)

XIANGSHENG BAO^1,2, QUANWEN LIU^1,2 & HAIYAN ZHOU^1*

¹Petroleum Engineering School, Guangdong University of Petrochemical Technology, Maoming 525000, China

²Institute of Development Seismology, Guangdong Research Center for Unconventional Energy Engineering Technology, Maoming 525000, China

Diserahkan: 30 Januari 2017/Diterima: 27 Mei 2017

ABSTRACT

Subei basin is the most promising onshore oil and gas bearing basin in South China. With the deepening of exploration, subtle hydrocarbon reservoirs have gradually become the major target of exploration. Seismic record often shows low signal to noise ratio (SNR), resulting that conventional seismic records have three shortcomings in the identification of subtle reservoirs: difficult to identify small faults; difficult to show the distribution law of sand body; and difficult to find traps. In order to solve this problem, we conducted the research on signal synthesis and decomposition. The research results showed that seismic record of different frequency bands can be restored from original seismic record and both of them contain real stratigraphic information. Based on this, when a certain band or several bands in the original seismic record is affected by noise and result in the reduction of SNR of seismic record, seismic information seriously affected by noise can be abandoned, leaving only less affected seismic information to obtain seismic record with higher SNR. In the collection of actual seismic record, the low and high band seismic information is seriously affected by noise, while medium-band seismic information is less affected. Therefore, based on this, the medium-band seismic information can be restored from the original seismic record to be new record, which is called predominant frequency band seismic record. In this paper, based on the research result, the predominant frequency band seismic record was applied to the two areas of Subei basin and the result showed the research result can be used as a good instruction on well placement and the improvement of drilling success rate.

Keywords: Low SNR; predominant frequency band seismic record; signal synthesis and decomposition; Subei basin; subtle reservoirs

ABSTRAK

Lembangan Subei merupakan daratan lembangan bearing minyak dan gas yang paling berpotensi di Selatan China. Dengan pendalaman penerokaan, takungan hidrokarbon tidak ketara secara beransur-ansur telah menjadi sasaran utama penerokaan. Rekod seismik sering menunjukkan isyarat rendah kepada nisbah hingar (SNR), menyebabkan rekod seismik konvensional mempunyai tiga kelemahan dalam pengenalpastian takungan tidak ketara: sukar untuk mengenal pasti kesilapan kecil; sukar untuk menunjukkan pembangunan hukum jasad pasir; sukar untuk mengenal pasti perangkap. Dalam usaha untuk menyelesaikan masalah ini, kami menjalankan uji kaji ke atas isyarat sintesis dan penguraian. Keputusan penyelidikan menunjukkan rekod seismik daripada jalur frekuensi berbeza boleh dipulihkan daripada rekod seismik asal dan kedua-duanya mengandungi maklumat stratigrafi asal. Berdasarkan maklumat ini apabila sesetengah jalur atau beberapa jalur dalam rekod seismik asal dipengaruhi oleh bunyi hingar dan mengakibatkan pengurangan SNR dalam rekod seismik, maklumat seismik teruk terjejas oleh hingar boleh ditinggalkan, meninggalkan hanya maklumat seismik yang kurang terjejas untuk mendapatkan rekod seismik dengan SNR lebih tinggi. Dalam pengumpulan rekod seismik yang sebenar, maklumat seismik jalur rendah dan tinggi teruk terjejas oleh bunyi hingar, manakala maklumat jalur sederhana seismik kurang terjejas. Oleh yang demikian, maklumat jalur sederhana seismik boleh dipulihkan daripada rekod seismik asal menjadi rekod baru yang dipanggil rekod seismik jalur frekuensi pradominan. Dalam kertas ini, berdasarkan keputusan kajian, rekod seismik jalur frekuensi pradominan digunakan untuk dua kawasan di lembangan Subei dan keputusan kajian menunjukkan ia boleh digunakan sebagai satu arahan yang baik untuk penempatan telaga serta pembaikan kadar kejayaan penggerudian.

Kata kunci: Isyarat sintesis dan penguraian; lembangan Subei; rekod seismik jalur frekuensi pradominan; SNR rendah; takungan halus

RUJUKAN

Anees, M.M., Qasim, M. & Bashir, A. 2017. Physiological and physical impact of noise pollution on environment. Earth Science Pakistan 1(1): 08-11.

Khan, A., Rehman, R., Rashid, H. & Nasir, A. 2017. Exploration of environmental friendly adsorbents for treatment of azo dyes from textile wastewater and its dosage optimization. Earth Science Pakistan 1(1): 05- 07.

Li, Q.Z. 1993. To the Way of Accurate Exploration - High Resolution Exploration Systems Engineering Analysis. Petroleum Industry Press.

Liang, B. 2007. Study on the accumulation of tertiary subtle reservoirs in Subei Basin, Beijing: PhD Thesis of China Mining University. pp. 1-2 (Unpublished).

Liao, W.T., Shi, X.G., Fan, L.X., et al. 2014. Research on the identification technology and evaluation method of overlap traps in the Dainan Formation of the North Slope of Gaoyou Sag. SINOPEC Jiangsu Oilfield.

Lu, J.M. & Wang, Y.G. 2014. The Principle of Seismic Exploration. Beijing: China University of Petroleum Press.

Mao, F.M., Liang, B. & Liu, Q.D. 2013. Gaoyou Sag Fault - Lithological Reservoir Exploration Technology and Practice. Beijing: Petroleum Industry Press.

Partyka, G., Gridley, J. & Lopez, J. 1999. Interpretational applications of spectral decomposition in reservoir characterization. The Leading Edge 18: 353-360.

Patterson, R.F. & Savas, E. 2016. On P-convergence of four dimensional weighted sums of double random variables. Sains Malaysiana 45(7): 1177-1181.

Qiu, X.T., Liu, Y.R. & Fu, Q. 2006. Cretaceous - Tertiary Sequence Stratigraphy and Sedimentary Evolution in Subei Basin. Beijing: Geological Publishing House.

Wang, Y., Chen, J.X. & Liao, W.T. 2015. The Application of Seismic Data in Subtle Traps Identification. Beijing: Petroleum Industry Press.

Yuan, J., Liang, H.Y., Liang, B., Dong, D.T., Min, W., Song, F. & Li, H.Y. 2016. Sedimentary characteristics and development model of lacustrine gravity flow: A case study of Dainan formation in deep sag belt of Gaoyou depression, Subei Basin. Acta Petrolei Sinica 37(3): 348-359.

Zhang, B.L. 1996. Signal Analysis and Processing Foundation. Beijing: Petroleum Industry Press.

Zhang, Z.Q., Wang, J., Wu, J.G., Chai, Y.B. & Wang, W. 2011. Identification method of structure traps and its application in low seismic data degree areas: Case studies on JZ20 - A structure. Offshore Oil 31(4): 29- 33.

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