INTERPRETASI STRUKTUR GEOLOGI PADA AREA GEOPARK CILETUH DENGAN ANALISIS DERIVATIF DATA GAYABERAT GGMPLUS

Geopark Ciletuh terletak di Kecamatan Ciemas sebelah barat Kabupaten Sukabumi, Jawa Barat, Indonesia. Pada Geopark Ciletuh terdapat adanya batuan Pra-Tersier yang tersingkap di permukaan dan juga terdapat berbagai macam struktur yang terbentuk akibat terjadinya pergerakan tektonik di sebelah barat daya Geopark Ciletuh. Penelitian ini dilakukan bertujuan mendelineasi struktur pada Geopark Ciletuh yang timbul oleh adanya perbedaan densitas dengan metode gaya berat. Pada penelitian ini digunakan analisis derivatif first horizontal derivative (FHD) untuk mengetahui keberadaan struktur dan second vertical derivative (SVD) untuk menentukan jenis patahan. Pada penelitian ini juga dilakukan dip estimation dengan metode multi-level second vertical derivative (ML-SVD). Setelah didapatkan data FHD, SVD, dan ML-SVD selanjutnya diintegrasikan dengan data geological section dari peta geologi Lembar Jampang Balekembang untuk dibuat penampang geologi. Interpretasi dugaan patahan memiliki arah orientasi NW-SE dan NE-SW. Hasil penelitian menujukkan adanya indikasi dugaan patahan naik dan patahan turun. Pada analisis terpadu, didapatkan adanya kesesuaian maupun ketidakkesesuaian antara data peta geologi dengan data geofisika.

Passive seismic data processing methods to identify contrast intrasalt interlayers in the geological section of the Astrakhan Arch

The article examines the problem of processing microseismic noise (MN) to identify and evaluate occurrence depth of contrasting geological objects – intersalt interlayers with a potentially high formation pressure. If it is impossible to use artificial wave sources, statistic processing of passive seismic data becomes critical. Due to the accumulation of power spectral density (PSD) during a long-term recording of MN the deterministic medium effect on a random signal spectrum is identified. PSD modulation when the surface or the bottom of the layered medium is exposed to white noise is expressed in terms of the Green’s function (GF) of a wave equation. Relevant GF variations corresponding to the layers form the basis for accumulated PSD approximation, and indicate the depth and contrast of the target features.

Engineering-Geological Zoning of the Railway Section by the Method of Probabilistic Assessment

The article describes the special engineering-geological zoning method of the railway territory. Permafrost geocryological conditions of the railway geological section were analyzed. The area is characterized by sporadic discontinuous permafrost. The analysis showed that the process of flooding is widely developed at the stusy area. It will have a great impact on the design and operation of the structure. The method of probabilistic assessment was used for a reasonable zonation of the territory. In result of the study, three taxa were identified that allows defining the flooded, potentially flooded, and non-flooded areas according to their geological structure. Measures for reducing the negative impact of flooding processes are recommended.

On the efficiency of integrated analysis of parameters of ref- racted and reflected waves in prediction of oil-gas bearing of section

Based on the comparative analysis of results of researches carried out via the methods of reflected and refracted waves with the purpose of prediction of geological section, the paper justifies that one of the major evidences in the field of seismic wave in oil-gas fields of geological section is the differentiation of elastic properties of oil-gas bearing reservoirs from the environment. Based on mutual comparison of results of conducted researches, it is shown that in the prediction of geological section the integ- rated analysis of changes of dynamic parameters of the waves reflected from the surface of oil-gas bearing reservoir and transmitted through this surface may further increase the reliability of obtained results. The research surveys carried out in Naftalan-Shimali Naftalan areas via the methods of reflected and refracted waves were simultaneously analyzed. With the aim of comparative analysis, the deposit type anomalies revealed through the method of refracted waves were compared to the results of attributed analysis of seismic cross-sections obtained with the method of common depth point. The correspondence of the signs associated with the oil-gas bearing content in change of dynamic parameters of refracted and reflected waves has been specified. With the purpose of prediction of geological section, a complex research is proposed.