Journal of the Geological Society of Korea (지질학회지)

The Geological Society of Korea (대한지질학회)
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Spatial distribution of hydrocarbon reservoirs in the West Korea Bay Basin in the northern part of the Yellow Sea, estimated by 3D gravity forward modeling

3차원 중력 모델링에 의해 예측된 황해 북부 서한만 분지 석유 저류층의 공간적 분포

  • Choi, Sungchan (Department of Geology, Kyungpook National University) ;
  • Ryu, In-Chang (Department of Geology, Kyungpook National University)
  • Received : 2018.11.20
  • Accepted : 2018.12.17
  • Published : 2018.12.31
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Abstract

Although an amount of hydrocarbon has been discovered in the West Korea Bay Basin (WKBB), located in the North Korean offshore area, geophysical investigations associated with these hydrocarbon reservoirs are not permitted because of the current geopolitical situation. Interpretation of satellite derived potential field data can be alternatively used to image three-dimensional (3D) density distribution in the sedimentary basin associated with hydrocarbon deposits. We interpreted the TRIDENT satellite-derived gravity field data to provide detailed insights into the spatial distribution of sedimentary density structures in the WKBB. We used 3D forward density modeling for the interpretation that incorporated constraints from existing geological and geophysical information. The gravity data interpretation and 3D forward modeling showed that there are two modeled areas in the central subbasin that are characterized by very low density structures, with a maximum density of about $2,000kg/m^3$, indicating some type of hydrocarbon reservoir. One of the anticipated hydrocarbon reservoirs is located in the southern part of the central subbasin with a volume of about $250km^3$ at a depth of about 3,000 m in the Cretaceous/Jurassic layer. The other hydrocarbon reservoir should exist in the northern part of the central subbasin, with an average volume of about $300km^3$ at a depth of about 2,500 m. A comparison between the TRIDENT derived gravity field and the ship-based gravity field measured in 1980s shows us that our results are highly reliable and there is a very high probability to detect another low-density layer existings in the northwestern part of the central subbasin.

북한의 서한만 분지 내에는 경제성이 있는 석유 자원이 존재할 것이라는 것이 여러 경로를 통해서 보고되고 있으나, 북한의 비밀주의 원칙에 의해서, 이 지역의 지질 및 지구물리학적인 연구를 위한 데이터가 공개된 적은 극히 드물었다. 그렇기 때문에 인공위성으로부터 제공되는 중력장 데이터는 서한만 퇴적분지의 구조를 밝혀내고, 이를 통해서 서한만 퇴적분지 내의 석유 부존자원 연구를 위해서 차선책으로 매우 유용하게 이용될 수 있다. 본 연구는 인공위성 데이터를 기반으로 만들어진 TRIDENT 중력장 데이터의 해석과 더불어 서한만 분지내에서 지금까지 수행된 지질 및 지구물리 데이터를 이용하여 서한만 퇴적분지의 3차원적인 밀도 구조를 밝혀내고자 수행되었다. 본 연구 결과, 서한만 분지 중, 2 군데의 지역에서 약 $2,000kg/m^3$의 매우 낮은 밀도를 특징으로 하는 저밀도 지층이 존재한다는 것을 확인하였으며, 이는 이 지역 퇴적분지 내에 석유 부존자원이 존재할 가능성이 매우 높다는 것을 시사한다. 한 곳은 서한만 중앙분지(Central basin) 남쪽 지역 약 3,000 m 깊이 백악기/쥐라기(Cretaceous/Jurassic) 층 속에 존재하며 그 부피는 약 $250km^3$으로 판단된다. 다른 곳은 중앙분지의 북쪽 지하 약 2,500 m에 위치하며, 그 부피는 약 $300km^3$으로 판단된다. 최근에 확보한 서한만 분지의 해상 측정 중력 데이터는 위의 연구 결과가 신빙성이 매우 높다는 것을 보여줌과 동시에 중앙분지 북서쪽 보하이만 방향으로 또 다른 저밀도 지층이 존재할 가능성이 매우 높다는 것을 보여준다.

Keywords

Acknowledgement

Grant : 기상.지진 See-At 기술개발연구

Supported by : 기상청

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