• The Korean Journal of Petroleum Geology
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• v.9 no.1_2 s.10
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• pp.24-39
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• 2001

Prospecting for energy and mineral resources is essential kind of public fundamentals that manage the nation's economy. Most explorations in the past were concentrated in the simple structural traps in relatively shallow depth. Due to their vast exploitation, recent history has shown that the emphasis in explorations has steadily shifted toward the subtle stratigraphic traps in deeper level. Increasing exploration for the subtle stratigraphic traps in deeper level requires precise correlation and assessment of deeply buried strata in the basin. However, the descriptive stratigraphic principles used for evaluation of the simple structural traps are limited to delineate the subtle stratigraphic traps in deeper depth. As this occurs, it is imperative to establish a new stratigrtaphic paradigm that allows a more sophisticated understanding on the basin stratigraphy. This study provides an exemplary application of integrated stratigraphic approach to defining basin stratigraphy of the Middle Ordovician Taebacksan Basin and the Cretaceous South Yellow Sea Basin, Korea. The integrated stratigraphic approach gives much better insight to unravel the stratigraphic response to tectonic evolution of the basins, which can be utilized for enhancing the efficiency of resources exploration and development in the basins. Thus, the integrated stratigraphic approach should be considered as a new stratigraphic norm that can improve the probability of success in any type of resources exploration and development project.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.59-74
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• 2003

Prospecting for energy and mineral resources is essential kind of public fundamentals that manage the nation's economy. Most explorations in the past were concentrated in the simple structural traps in relatively shallow depth. Due to their vast exploitation, recent history has shown that the emphasis in explorations has steadily shifted toward the subtle stratigraphic traps in deeper level. Increasing exploration for the subtle stratigraphic traps in deeper level requires precise correlation and assessment of deeply buried strata in the basin. However, the descriptive strati-graphic principles used for evaluation of the simple structural traps are limited to delineate the subtle stratigraphic traps in deeper depth. As this occurs. it is imperative to establish a new stratigraphic paradigm that allows a more sophisticated understanding on the basin stratigraphy. This study provides an exemplary application of integrated stratigraphic approach to defining basin history of the Middle Ordovician Taebacksan Basin, Korea. The integrated stratigraphic approach gives much better insight to unravel the stratigraphic response to tectonic evolution of the basins, which can be utilized fer enhancing the efficiency of resources exploration and development in the basins. Thus, the integrated stratigraphic approach should be emphasized as a new stratigraphic norm that can improve the probability of success in any type of resources exploration and development project.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.285-290
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• 2002

조사지역은 전라남도 함평군 함평읍으로부터 남쪽으로 엄다면 화양리, 학야리, 성천리 일대에 발달한 충적층으로서. 이 지역에는 남서-북동방향으로 광주단층이 통과하고 있는 것으로 추정된다. 충적층 하부에 발달한 단층을 포함한 대규모 파쇄대 파악에는 지표지질조사로서 한계가 있다. 따라서 이 연구에서는 물리탐사방법을 적용하여 충적층 하부의 대규모 파쇄대의 방향과 연장성을 파악하고자 하였으며, 사용된 물리탐사법은 전기비저항 2차원탐사, 전자탐사 그리고 자력탐사이다. 전기비저항 탐사결과 충적층 내에서 남북방향의 연장성을 갖는 전기비저항 이상대가 파악되었으나, 자력탐사와 전자탐사의 측정자료에는 이 이상대에대한 반응을 관찰할 수 없었다. 이는 전자탐사의 경우, 가탐심도가 매우 작은 EM31을 사용하였고, 또한 자력탐사는 주변 지질매체 간의 대자율 차이가 없는 것에 기인한 것으로 판단된다. 따라서 향후 지하심부의 탐사를 위해 전자탐사법중 TEM 탐사를 실시할 계획이며, 또한 낮은 전기비저항 이상대의 연장성을 정확히 파악하기 위하여 기 측정된 전기비저항 탐사 측선 사이를 탐사할 예정이다.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.19-28
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• 2007

In this study, we propose a joint inversion method, using genetic algorithms, to estimate an S-wave velocity structure for deep sedimentary layers from receiver functions and surface-wave phase velocity observed at several sites. The method takes layer continuity over a target area into consideration by assuming that each layer has uniform physical properties, especially an S-wave velocity, at all the sites in a target area in order to invert datasets acquired at different sites simultaneously. Numerical experiments with synthetic data indicate that the proposed method is effective in reducing uncertainty in deep structure parameters when modelling only surface-wave dispersion data over a limited period range. We then apply the method to receiver functions derived from earthquake records at one site and two datasets of Rayleigh-wave phase velocity obtained from microtremor array surveys performed in central Tokyo, Japan. The estimated subsurface structure is in good agreement with the results of previous seismic refraction surveys and deep borehole data. We also conclude that the proposed method can provide a more accurate and reliable model than individual inversions of either receiver function data only or surface-wave dispersion data only.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.61-68
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• 2010

A magnetotelluric (MT) survey has been performed to delineate deeply extended fracture systems at the geothermal field in Seokmo Island, Korea. To assist interpretation of the MT data, geological surveying and well logging of existing wells were also performed. The surface geology of the island shows Cretaceous and Jurassic granite in the north and Precambrian schist in the south. The geothermal regime has been found along the boundary between the schist and Cretaceous granite. Because of the deep circulation along the fracture system, geothermal gradient of the target area exceeds $45^{\circ}C/km$, which is much higher than the average geothermal gradient in Korea. 2D and 3D inversions of MT data clearly showed a very conductive anomaly, which is interpreted as a fracture system bearing saline water that extends at least down to 1.5 km depth and is inclined eastwards. After drilling down to the depth of 1280 m, more than 4000 tons/day of geothermal water overflowed with temperature higher than $70^{\circ}C$. This water showed very similar chemical composition and temperature to those from another existing well, so that they can be considered to have the same origin; i.e. from the same fracture system. A new geothermal project for combined heat and power generation was launched in 2009 in Seokmo Island, based on the survey. Additional geophysical investigations including MT surveys to cover a wider area, seismic reflection surveys, borehole surveys, and well logging of more than 20 existing boreholes will be conducted.

• Economic and Environmental Geology
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• v.33 no.6
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• pp.525-536
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• 2000

Electromagnetic and electric surveys were performed to reveal the deep structure of the Yangsan fault in the Bong-gye and Unyang areas, Kyeongnam Province, Korea. Especially, high-frequency magnetotelluric (HFMT) method of EM survey was mainly employed to study the deep subsurface configuration of Yangsan fault. HFMT survey was performed at 25 points of spacing 50 m, making 1.3 km survey line in Unyang area and 13 points of spacing 50 m, making 0.6 km survey line in Bong-gye area. Two 2-D cross-sections (Unyang and Bong-gye areas) were achieved as results. Electric survey by dipole-dipole array was performed to study the structure of shallow subsurface and compare the results with HFMT surveys. The results of HFMT and electric surveys show that Yangsan fault is a geologic boundary. It is very narrow and steep (about $80^{\circ}C$), and extends to 1~1.5 km depth.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.437-444
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• 2002

Geomagnetic depth sounding (GDS) was performed to analyze the characteristics of deep resistivity structure in and around the Korean Peninsula. The data that have 0.01 nT precision were collected from 5 geomagnetic observatories and measured every one or five second. In this study, amount of 16 days of geomagnetic data were used for analyzing. Generally the sea affects the GDS data seriously due to its high conductivity. However, though the Korean peninsula is surrounded by seas in three sides, the results given by induction arrow strongly show that the trend of electrical conductivity at neighborhood of the Korean Peninsula is reigned by some geological features. Also it is believed that observation in Jeju island is related with the electrical structure around the East China Sea.

• Geophysics and Geophysical Exploration
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• v.26 no.3
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• pp.138-149
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• 2023

In geoscience and engineering the geological characteristics of sediment strata is crucial and possible if reliable borehole logging and seismic data are available. To investigate the characteristics of the shallow strata in the Korea Strait, laboratory sonic logs were obtained from deep borehole data and seismic section. In this study, we integrated and analyzed the sonic log data obtained from the drilling core (down to a depth of 200 m below the seabed) and multichannel seismic section. The correlation value was increased from 15% to 45% through time-depth conversion. An initial model of P-wave impedance was set, and the results were compared by performing model-based, band-limited, and sparse-spike inversions. The derived P-impedance distributions exhibited differences between sediment-dominant and unconsolidated layers. The P-impedance inversion process can be used as a framework for an integrated analysis of additional core logs and seismic data in the future. Furthermore, the derived P-impedance can be used to detect shallow gas-saturated regions or faults in the shallow sediment. As domestic deep drilling is being performed continuously for identifying the characteristics of carbon dioxide storage candidates and evaluating resources, the applicability of the integrated inversion will increase in the future.

• The Science & Technology
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• v.9 no.8 s.87
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• pp.23-27
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• 1976

우리나라에서 본격적으로 물리탐사를 시도한것은 1958~1960년에 실시한 항공자력탐사로서 그후 현재까지 불과 20년이 지나지 않았다. 그간 물리탐사의 기술발전으로 자원탐사분야에 많은 공헌이 있었다. 현재까지 주로 적용된 분야는 철자원탐사를 위한 자력탐사, 지하수조사를 위한 전기비저항탐사동, 연등의 통화금속광물탐사를 위한 각종 전기탐사, 제3기층 지질구조와 땜공사, 공업단지조성등의 기반암조사, 그리고 광산의 갱내 출수조사등을 위한 탄성파탐사, 우라늄자원을 위한 방사능탐사, 그리고 해저지질 및 자원조사를 위한 해상물리탐사등이다. 이와 동시에 석탄층조사를 위한 전기탐사 및 Model연구자력탐사의 전산처리 적용, 그리고 광물 및 암석의 물리적 성질등 학술분야에 대한 기초연구도 계속하여 왔다. 우리나라에 있어 물리탐사의 적용조건은 비교적 험악한 지형, 복잡한 지질구조, 광상의 불규칙 또는 소규모의 발달과 산재등이다. 이와 같은 특징은 탐사해석의 정도를 높이기 위하여 보다 고도의 과학기술문제의 해결을 요구하고 있으며 이와 동시에 현대적 탐사방법과 연구개발로 대상자원의 탐사지역확대와 지하심부 탐사등이 당면과제이다. 기술과제로서는 석탄 및 기타자원에 대한 물리검층탐사, 경상계 지질구조구명을 위한 탄성파탐사 및 동력탐사의 적용, 항공자력, 전자 및 방사능탐사 및 해양의 각종물리탐사의 기술개발이 있으며 그외 탐사자료의 전산처리기술 및 지구과학의 기초연구등이 있다.

• 한국지구과학회:학술대회논문집
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• 2003.09a
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• pp.35-36
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• 2003