• Economic and Environmental Geology
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• v.46 no.4
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• pp.359-373
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• 2013

Shale is considered as a source rock for conventional oil and gas exploration and development because shale is fine-grained detrital sedimentary rock which can preserve the organic matter better. Shale has a good sealing capacity for the petroleum trap due to its low permeability. Commercial recoveries of gas from shale in the North America based on the development of technologies of horizontal drilling and hydraulic fracturing reveal that shale also function as a effective reservoir rock. Geochemical techniques to evaluate generation potential of the hydrocarbons from organic matter in the source rocks can be applied for the exploration of the shale gas resources. To evaluate shale gas resources, it is important to understand various geochemical processes and shale characteristics controlling generation, storage and estimation of shale gas reserves. In this paper, the generation mechanism of the oil and gas from organic matter is reviewed, and geochemical techniques which can be applied for the evaluation and characterization of shale gas are introduced.

• Journal of the Korean Geophysical Society
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• v.3 no.4
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• pp.227-234
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• 2000

Amplitude anomalies or bright spots are often linked to hydrocarbon-bearing reservoirs but can also be caused by tuning effect resulting from interference when two reflectors are close together. Tuning effect can be removed from amplitude maps before seismic amplitude and reservoir thickness data are converted into estimates of hydrocarbon accumulations. The most straightforward way of removing tuning effect or 'detuning' is by comparing the reservoir amplitude in seismic data with the response of wedge or thin-bed models and calibrating the reservoir amplitude using the tuning curves from the models. Volumetric estimation for amplitude plays must be based on detuned amplitude maps because hydrocarbon volumes can be significantly overestimated when conventional amplitude maps are used.

• Geophysics and Geophysical Exploration
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• v.9 no.2
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• pp.163-170
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• 2006

The shortage of proven hydrocarbon reserves has resulted in exploration progressing from the offshore into progressively deeper water of the continental shelf. Despite the success of seismic acquisition at ever greater depths, there are marine geological terrenes in which the interpretation of seismic data is difficult, such regions dominated by scattering or high reflectivity that is characteristic of carbonate reefs, volcanic cover and submarine permafrost. A marine controlled-source electromagnetic (CSEM) method has recently been applied to the oil and gas exploration thanks to its high-resistivity characteristics of the hydrocarbon. In particular, this method produces better results in terms of sensitivity under the deep water environment rather than the shallow water. Only in the last five years has the relevance of CSEM been recognized by oil companies who now use it to help them make exploration drilling decisions. Initial results are most promising and several contractors now offer magnetotelluric and CSEM services.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.97.1-97.1
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• 2011

저온에서 양이온 고분자막을 사용하는 고분자 연료전지의 경우 뛰어난 성능과 다양한 응용분야로 인해 많은 연구와 실증이 이루어지고 있지만 공기극에서의 느린 산소 환원반응으로 인해 백금과 같은 귀금속의 사용이 불가피하고 백금의 제한된 매장량과 높은 가격으로 인해 상용화가 늦어지고 있다. 그래서 많은 연구자들이 합금 촉매 또는 비귀금속 촉매를 이용한 전극 개발에 집중하고 있다. 알칼리 분위기에서 저가의 전이 금속들이 백금과 비슷한 활성을 보이고 고체 음이온 교환막이 개발됨에 따라 최근 알칼리 연료전지가 다시금 큰 주목을 받고 있다. 그러나 고분자 연료전지와는 달리 아직 촉매나 전해질막, 이오노머의 특성 및 메커니즘에 관해 별로 알려진 것이 없다. 본 연구에서는 직접 개발한 세공충진막 형태의 탄화수소계의 음이온 교환막과 비귀금속 공기극 촉매를 이용하여 막전극접합체(MEA)를 개발하였고 촉매 및 이오노머 함량과 같은 전극 조성, 막전극접합체의 제조 및 체결, 가습이나 가스조성 등의 단위전지 운전조건과 같은 다양한 변수에 대해에 최적 조건을 도출하고자 하였다. 공기극 촉매는 Cu-Fe/C를 이용한 상용 촉매를 이용하였고 이오노머의 경우는 탄화수소계의 상용 제품을 사용하였으며 음이온 교환막에 전극층을 형성하기 위해서는 스프레이 공정을 이용하였다. 단위전지를 통해 성능을 확인하였고 임피던스 및 CV를 통해 전기화학적인 특성을 규명하였다. 조건의 최적화를 통해 상당한 성능 향상을 이루었으나 추가적인 성능 향상 및 내구성 확보 등에 대해 계속적인 실험을 진행할 예정이다.

• The Korean Journal of Petroleum Geology
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• v.7 no.1_2 s.8
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• pp.13-18
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• 1999

Methane hydrate is an ice-like solid material and it has a structure which water molecules enclose gas molecules. For low temperature and high pressure, hydrocarbon gas forms hydrate and due to this condition, it is existed in the arctic region or deep sea. Presently, the amount of methane hydrate is unpredictable, but it is assumed that the amount will be enormous. For this reason, it is expected that it will play a major role as natural gas resources in the future. However, the production technologies are stayed on the low level and the economical technology was not developed yet. Also, emission of natural gas from methane hydrate will cause global warming and thus it is considered as a critical environmental problem. In this paper, the state of the art of the production technologies and environmental effects of methane hydrate were summarized.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.665-673
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• 2011

In order to estimate the hydrocarbon reserves, the porosity of the reservoir must be determined. The porosity of the area without a well is generally calculated by extrapolating the porosity logs measured at wells. However, if not only well logs but also seismic data exist on the same site, the more accurate pseudo porosity log can be obtained through artificial neural network technique by extracting the relations between the seismic data and well logs at the site. In this study, we have developed a module which creates pseudo porosity logs by using the polynomial neural network method. In order to obtain more accurate pseudo porosity logs, we selected the seismic attributes which have high correlation values in the correlation analysis between the seismic attributes and the porosity logs. Through the training procedure between selected seismic attributes and well logs, our module produces the correlation weights which can be used to generate the pseudo porosity log in the well free area. To verify the reliability and the applicability of the developed module, we have applied the module to the field data acquired from F3 Block in the North Sea and compared the results to those from the probabilistic neural network method in a commercial program. We could confirm the reliability of our module because both results showed similar trend. Moreover, since the pseudo porosity logs from polynomial neural network method are closer to the true porosity logs at the wells than those from probabilistic method, we concluded that the polynomial neural network method is effective for the data sets with insufficient wells such as F3 Block in the North Sea.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.187-201
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• 2014

Compared with the separated inversion of electromagnetic (EM) and seismic data, a joint inversion using both EM and seismic data reduces the uncertainty and gives the opportunity to use the advantage of each data. Seismic fullwaveform inversion allows velocity information with high resolution in complicated subsurface. However, it is an indirect survey which finds the structure containing oil and gas. On the other hand, marine controlled-source EM (mCSEM) inversion can directly indicate the oil and gas using different EM properties of hydrocarbon with marine sediments and cap rocks whereas it has poor resolution than seismic method. In this paper, we have developed a joint EM inversion algorithm using a cross-gradient technique. P-wave velocity structure obtained by full-waveform inversion using plane wave encoding is used as structure constraints to calculate the cross-gradient term in the joint inversion. When the jointinversion algorithm is applied to the synthetic data which are simulated for subsea reservoir exploration, images have been significantly improved over those obtained from separate EM inversion. The results indicate that the developed joint inversion scheme can be applied for detecting reservoir and calculating the accurate oil and gas reserves.

• Geophysics and Geophysical Exploration
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• v.18 no.3
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• pp.125-132
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• 2015

The water saturation ($S_w$), which is very important to estimate hydrocarbon reserves in the reservoir, has been determined from resistivity index (RI) by using the Archie's formula. However, in many cases, it has been reported that n is not constant for a given formation and it could be varied with water saturation. In addition, it frequently happens that the line obtained by linear regression analysis on log-log scale does not pass through the origin. In order to overcome these drawbacks, we suggested a modified Archie's formula, which can handle almost all the RI vs. $S_w$ cross-plots whether the trend is straight or curved and whether it passes through the origin or not. We also demonstrated that how to determine conductivity exponent ${\mu}$, critical water saturation $S_c$, and saturation distribution factor b in the laboratory to use the modified Archie's formula. Since the modified Archie's formula takes into account pore structure, pore water distribution, and wettability of reservoir such as clean sandstone and carbonate rocks, it might improve field applicability.

• Economic and Environmental Geology
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• v.44 no.1
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• pp.83-94
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• 2011

Extra heavy oil reservoirs are distributed over the world but most of them is deposited in the northern part of the Orinoco River in Venezuela, in the area of 5,500 $km^2$, This region, which has been commonly called "the Orinoco Oil Belt", contains estimated 1.3 trillion barrels of original oil-in-place and 250 billion barrels of established reserves. The Venezuela extra heavy oil has an API gravity of less than 10 degree and in situ viscosity of 5,000 cP at reservoir condition. Although the presence of extra heavy oil in the Orinoco Oil Belt has been initially reported in the 1930's, the commercial development using in situ cold production started in the 1990's. The Orinoco heavy oil deposits are clustered into 4 development areas, Boyaco, Junin, Ayachoco, and Carabobo respectively, and they are subdivided into totally 31 production blocks. Nowadays, PDVSA (Petr$\'{o}$leos de Venzuela, S.A.) makes a development of each production block with the international oil companies from more than 20 countries forming a international joint-venture company. The Eastern Venezuela Basin, the Orinoco Oil Belt is included in, is one of the major oil-bearing sedimentary basins in Venezuela and is first formed as a passive margin basin by the Jurassic tectonic plate motion. The major source rock of heavy oil is the late Cretaceous calcareous shale in the central Eastern Venezuela Basin. Hydrocarbon materials migrated an average of 150 km up dip to the southern margin of the basin. During the migration, lighter fractions in the hydrocarbon were removed by biodegradation and the oil changed into heavy and/or extra heavy oil. Miocene Oficina Formation, the main extra heavy oil reservoir, is the unconsolidated sand and shale alternation formed in fluvial-estuarine environment and also has irregularly a large number of the Cenozoic faults induced by basin subsidence and tectonics. Because Oficina Formation has not only complex lithology distribution but also irregular geology structure, geological evolution and characteristics of the reservoirs have to be determined for economical production well design and effective oil recovery. This study introduces geological formation and evolution of the Venezuela extra heavy oil reservoirs and suggest their significant geological characteristics which are (1) thickness and geometry of reservoir pay sands, (2) continuity and thickness of mud beds, (3) geometry of faults, (4) depth and geothermal character of reservoir, (5) in-situ stress field of reservoir, and (6) chemical composition of extra heavy oil. Newly developed exploration techniques, such as 3-D seismic survey and LWD (logging while drilling), can be expected as powerful methods to recognize the geological reservoir characteristics in the Orinoco Oil Belt.

• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.28-46
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• 2001

Natural gas is a mixture of hydrocarbon gases and impurities such as nitrogen, hydrogen sulfide, and carbon dioxide and a clean energy producing no pollution materials for combustion. Currently, the demand of the natural gas is rapidly increasing due to worldwide environmental problems. According to Hubbert's study in the past, the natural gas was predicted as rapidly depleted resources, and then the results led to high gas price and limitation of usage during 1980s. Afterward, the study of natural gas resources based on geology identified the additional natural gas resources that were not considered in Hubbert's study. They are unconventional gas, additional resources in the existed reservoirs, and natural gas in deep subsurface areas. Such additional resouces made the future of natural gas bright and pormised low and stable gas price in the future. Deep natural gas is defined as the gas existing at or below 15,000ft$(4,752{\cal}m)$ in depth from the surface. According to the study from the U.S. Geological Survey(USGS) in 1995, 1,412 TCF of technically recoverable natural gas was remained to be discovered or developed in the onshore of United States. A significant part of that resource base, 114 TCF, exists at deep sedimentary basins, and it shows wide distribution with various geological environments. In 1995, the deep gas contributed to $6.7\% of total supply amount of natural gas in the United States and is expected to be $18.7\% by 201.5. However, the development of the deep gas is a high risky business due to expensive investment and high portion of dry holes, although it is developed. Thus, for developing the deep gas economically, it is necessary to overcome many technical challenges. In this paper, for increasing success rate of the deep gas, 1) geologic and compositional characteristics, and production cost have been analyzed according to depth, 2) technical problems related to deep gas production have been summarized, and 3) finally future study areas for increasing application of the deep gas have been suggested. For reference, this paper was written based on the study results from USGS and Gas Research Institute(GRI), for the United States is doing the most active R&D in the deep gas area, and thus, has many reliable data.