Nonstationary Signal Extraction Based on Bat Algorithm Sparse Decomposition Technique

For nonstationary time series i.e. natural electromagnetic field and acoustical signal, effective signal extraction always requires prior knowledge or hypothesis, and hardly do without artificial judgment. We proposed bat algorithm sparse decomposition (BASD) to realize adaptive recognition and extraction of nonstationary signal in a noisy background. We designed two general atomics for typical signals, and developed dictionary training method based on correlation detection and Hilbert transform. The sparse decomposition was turned into an optimizing problem by introducing bat algorithm with optimized fitness function. By contrast with variational modal decomposition, it was indicated that BASD can effectively extract short time target without inducing global aliasing of local feature, and no preset mode number and late screening were needed.

MAGNETOTELURIC AND MAGNETOVARIATE RESEARCHES IN THE ENDOCONTACT AREA OF KORNINSKY GRANITE ARRAY

In 2018-2019, work was carried out to study the deep geoelectric structure of a complex system of intersection of the sub-latitudinal zone between the Andrushevsky and Masherinsky faults and the sub-meridional between Brusilovsky and Olshansky. Plane synchronous observations of the lowfrequency natural electromagnetic field of the Earth of ionospheric-magnetospheric origin in a wide range of periods are made. The transmission operators of MT/MV fields were evaluated using the PRC-MTMV software package. The obtained tipper estimates for periods of geomagnetic variations from 50 to 3100 s, curves of apparent resistance and impedance phases from 20 to 10000 s. According to the interpretation of the results of magnetotelluric studies, the Brusilovsky deep fault in the form of a subvertical surface lowresistance anomaly was clearly recorded. Analyzing these and previous works, it can be stated that within the Volyn megablock Ukrainian shield, the Brusilovsky deep fault is manifested by an anomalous highly conductive structure from the surface. Within the framework of the Rosinsky megablock, the Brusilov fault zone is not completely anomalous, and only its individual components (Velikoerchik fault) are anomalous, its conductivity decreases almost four times. The western border of the Korninsky massif is less clearly distinguished, as the relatively electrically conductive from the surface, which is most likely associated with the surface conductivity of minor sedimentary deposits or fracturing of rocks in the crystalline basement. It should also be emphasized that on pseudo-sections of magnetotelluric parameters, the SUS point (picket 14 km) did not appear to be anomalous, but the behavior of the curves for different polarizations, and especially low magnetovariational characteristics, may indicate that the deep structure of the region must be classified as heterogeneous. Moreover, this point is located near the zone of metasomatically altered rocks and multidirectional faults of low rank. One explanation of this may be that the processes of secondary changes in granitoids do not lead to an increase in porosity, the solutions which are filtered are immediately saturated with calcium and alkalis, filling the fluid flow paths.

ANALISIS PENAMPANG RESISTIVITAS 2D METODE MAGNETOTELLURIK DAN AUDIO-MAGNETOTELLURIK UNTUK MENGETAHUI SISTEM PETROLEUM PADA CEKUNGAN SINGKAWANG

Indonesia memiliki cadangan minyak bumi potensial yang cukup banyak, salah satunya terdapat pada Pulau Kalimantan. Pada bagain barat pulau ini memiliki cekungan besar, yakni Cekungan Melawi dan Cekungan Ketungau. Kedua cekungan ini diperkirakan berumur pra-tersier. Tetapi, kedua cekungan ini tidak memiliki potensi ekonomis untuk migas konvensional, dan diperkirakan ada satu cekungan lain yang beumur sama dengan kedua cekungan ini. Cekungan ini dikenal sebagai Cekungan Singkawang. Cekungan ini diperkirakan memiliki sistem petroleum yang tersusun dari formasi Batupasir Kayan, Formasi Pendawan, Formasi Brandung, Kelompok Bengkayang serta Formasi Seminis. Untuk menganalisis struktur ini, digunakan metode magnetotellurik dan audio-magnetotellurik yang memanfaatkan medan elektomagnetik alam. Data yang diperoleh dari kedua metode ini masing-masing terdiri dari 14 titik dengan 2 lintasan. Lintasan pertama terdiri dari 10 stasiun pengukuran dan lintasan kedua dengan 5 titik pengukuran. Data ini merupakan data yang didapatkan dari rentang frekuensi 320 – 0,00034 Hz untuk metode magnetotellurik dan 3,3 – 10400 Hz untuk metode audio-magnetotellurik. Berdasarkan kedua metode ini, diperoleh lapisan dengan nilai resistivitas dengan rentang 4 – 54 Ωm yang diperkirakan sebagai Kelompok Bengakayang yang berpotensi sebagai batuan sumber (source rock). Sedangkan lapisan dengan nilai resistivitas 119 – 437 Ωm diperkirakan sebagai Vulkanik Raya dan 1611 – 3532 Ωm sebagai Granodiorit Mensibau. Kedua formasi ini diperkirakan sebagai batuan reservoir (reservoir rock), meskipun untuk penentuan jenis batuan ini sebagai batuan reservoir harus diteliti lebih lanjut lagi.Indonesia has lot of potential of reserved crude oil, one of the region has a lot reserved is Borneo Island. In this island, there are two huge basin located in the west, there are Melawi Basin and Ketungau Basin. Both of the basin approximately pre-tertiary aged. But both of the basin has not economic potential for conventional oil and gas, and probably there is other basin that has similar age with these basin. The name of the basin is Singkawang Basin. This basin predicted has petroleum system consists of Batupasir Kayan, Formasi Pedawan, Formasi Brandung, Kelompok Bengkayang, and Formasi Seminis. Magnetotelluric and audio-magnetotelluric method use to analyze this system. These method using natural electromagnetic field. Data obtained from this measurement consists of 14 measuring station with 2 line. First line consist 10 measuring station and second one consist 5 measuring station. This data also obtained from frequency range 320 – 0,00034 Hz for magnetotelluric method and 3,3 - 10400 Hz for audio-magnetotelluric method. Based these result, show that structure with resistivity value beetwen 4 – 54 Ωm predicted as Kelompok Bengkayang potentially to be source rock, while the layer with resistivity 19 – 437 Ωm predicted as Vulkanik Raya and 1611 – 3532 Ωm predicted as Granodiorit Mensibau. Both of the formation potentially as reservoir rock, although to determine the information of this formation as reservoir rock must be researched further.Keywords: Petroleum system; Singkawang Basin; Magnetotellurics; and Audio-magnetotellurics

Deformation-Electromagnetic Relations in Lithospheric Activity Manifestations

It has been shown that dipole radiation of accelerated charges, described by Larmor relation, is the basis of the known mechanic-electromagnetic processes of rock deformation. Comparison of crust deformation acceleration with natural electromagnetic field parameters of ELF-VLF range showed good relation. It manifests in the maxima of occurrence frequency density of synchronous deformation-electromagnetic events on two dimensional histograms. The data of a laser strain-meter and a recorder of natural electromagnetic radiation of ELF-VLF range, recorded in a zone of increased seismic activity (Kamchatka, Karymshina site), were used. The authors made an assumption on the existence of stationary regions of deformation process and mechanic-electromagnetic transformations corresponding to regions with different mechanic properties and rock petrographic composition.

Nonstationary processes of acousto-electromagnetic emission of the lithosphere in a seismic active region resulted from surface and borehole measurements

The results of synchronous detection of the emission of various components of the electromagnetic and acoustic fields obtained under conditions of low industrial interference and a high level of microseismicity are investigated. To compensate electromagnetic radiation of lithospheric origin, a compensation method was used. The signal loop antenna, recording a mixture of signals of lithospheric and atmospheric-thunderstorm origins, was used as a magnetic core of a steel casing of the borehole. The compensating signal was recorded using an antenna, the receiving coil of which was identical to the coil of the signal antenna. The measurements were carried out in the seismically active region of Russia (the Kamchatka peninsula, the Paratun hydrothermal deposit) at the intersection of the sublatitudinal and submeridional fault zones. Methods for analyzing registration data of non-stationary processes are considered using the example of acoustic-electromagnetic emission of the lithosphere, the electromagnetic component of which is a component of the natural electromagnetic field of the Earth. Their characteristics are estimated and a statistical model is proposed that uses nested semi-Markov processes and finite atomic functions. Observations of geophysical electromagnetic fields, in addition to useful information about the emission processes, contain interference, mainly of technogenic origin. They are especially strong in downhole measurements when a well casing is used as the receiving antenna. These interferences significantly impede the allocation of useful information. The possibility of using bleaching filters to increase the contrast of observation of useful signals of lithospheric origin against their background is considered.