• The Korean Journal of Petroleum Geology
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• v.14 no.1
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• pp.36-44
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• 2008

Natural gas in tight reservoirs, one of unconventional hydrocarbon resources, has become a significant exploration and exploitation targets. Tight gas reservoirs are the gas-bearing rocks that commonly have a permeability of less than 0.1 millidarcy (mD). Tight gas reservoirs are characterized by extensive and deep locations as well as abnormal pressure such as over- or under-pressure. The tight gas reservoirs are independent of structural or stratigraphic traps, whereas conventional gases normally occur at these traps. Tight gas reservoirs can be productive when stimulated by hydraulic fracturing. Better production areas within the tight reservoir beds are referred to as sweet spots that are commonly caused by natural fractures, which should be understood and identified to enhance the recovery of the gas from tight reservoirs. The exploration and production techniques allow the commercial production of tight gas, one of environmentally friendly resources. Slant and horizontal wells have best production when they intersect the fractures. Gas production from the tight reservoirs has rapidly grown in U.S. and Canada. Indeed, the U.S. gas production of tight sandstones increases from 11.1% in 1990 to 24.1% in 2005. The presence of tight gas reservoirs has been suggested on the Korean offshore block 6-1. Paradigm shift from conventional to unconventional tight reservoir is required to develop the tight gas from the block.

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.249-251
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• 2007

• Economic and Environmental Geology
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• v.47 no.5
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• pp.551-561
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• 2014

Natural gas is the world's fastest-growing fossil fuel, with consumption increasing from 113 trillion cubic feet(Tcf) in 2010 to 185Tcf in 2040. While conventional natural gas streams from the earth relatively easily, unconventional gas finds are more difficult to develop and more costly to produce. Right now, there are six main types of unconventional gas, including deep gas, gas-containing shale, coalbed methane(CBM), geopressurized zones, Arctic and subsea hydrates, and tight gas. Tight gas refers to natural gas reservoirs locked in extraordinarily impermeable, hard rocks(sandstone, siltstone or carbonate sedimentary rocks). In this study, we analyzed total 375 papers(2000-2014) of tight gas by country, institution, international cooperation etc.

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.20-30
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• 2014

To develop a unconventional gas reservoir, an analysis of tight rock property are required. Especially, conventional measurements are difficult to be applied to unconventional resources such as tight gas reservoir because the permeability are extremely low compared to a conventional gas reservoir. In this study, an apparatus was developed for measuring low permeability and porosity based on a pressure pulse decay method under unsteady state conditions. The apparatus was applied for measuring the porosity and permeability of tight sand core samples from Gyeongsang basin in Korea. As a validation of the measurement, regression analysis was carried out using the dimensionless pseudo-pressure between the measured data and analytical solution. The results show the correlation coefficients above 0.96. Therefore, it is believed that the apparatus has a high accuracy.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.659-664
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• 1998

Densification behavior of $Si_3N_4$ ceramics by two step gas pressure sintering was compared with pres-sureless sintering one step gas pressure sintering or hot isostatic pressing. While it was difficult to get the highly interlocked ${\beta}-Si_3N_4$ microstructure during the pressureless sintering due to decomposition above $1800^{\circ}C$ gas pressure sintering could solve this problem by increasing the densification temperature 2MPa of nitrogen pressure was enough to inhibit the decomposition up to $1890^{\circ}C$ and especially two step gas pres-sure sintering applying comparatively low pressure(2MPa) until the closed pore stage and then high pres-sure(10MPa) after pore closure could increase the hardness and the toughness.

• Korean Journal of Mineralogy and Petrology
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• v.37 no.3
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• pp.87-109
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• 2024

Two kinds of basaltic outcrop consisting of vesicular gas-pipe and the host massive basalt were observed in the Taeheung-ri area of Namwon-eup, Jeju Island. This is clear evidence of the magmatic differentiation of lava flows after an eruption. Although the petrographic study revealed that both parts contained the same mineral phases such as olivine, clinopyroxene, and plagioclases with accessory alkaline feldspar, and titanite, their contents and compositions are more evolved in the vesicular gas-pipe. Its anorthite and wollastonite contents in plagioclase and clinopyroxene, respectively, are lower than those of the host massive basalt. The whole-rock XRF analysis indicates that vesicular gas-pipe had lower MgO content and higher CaO, Al₂O₃, P₂O₅, Fe₂O₃, Na₂O, TiO₂, SiO₂, and K₂O contents than those of the host massive basalt. Both parts of basalt are classified as tholeiite in the TAS diagram, but the former is plotted in a more differentiated area with higher SiO₂ content than the latter. Large ion lithophile elements are enriched in both types of basalt, but the enrichment is more conspicuous in the former. Rare earth elements are more abundant n porous gas-pipe than in the host massive basalt. In particualr light rare earth elements are highly enriched in both types of basalt ralative to those of chondrite, indicating typical ocean island basalts (OIBs). These findings indicate that the magma differentiation possibly occurred after an eruption, which can be explained by the gas-driven filter-pressing.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.468-475
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• 2006

For the filtration of super compactible cake, the high filtration pressure can not improve filtration rate. As the high pressure, in this case, decreases the cake porosity adjacent to filter medium and thus forms 'dense skin' which decreases the rate of liquid flow in a great extent. Actually, there was no method to improve filtration rate for the filtration with super compactible cake. We propose the saturation of $CO_2$ gas into the suspension before the filtration operation for improving the filtration rate. The dissolved $CO_2$ gas transforms itself into gas phase in the dense skin through which the pressure changes dramatically. The gas secures its space inside the dense skin, and finally forms the flow passages which improve the filtration rate.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.67-67
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• 2010

본 연구에서는 마그네트론 스퍼터링법을 이용하여 가볍고 내구성이 뛰어난 Al을 다양한 공정 조건에서 냉연 강판에 코팅하여 코팅층의 밀도 측정으로부터 치밀도를 알아보았다. 99.95% 순도의 Al 타겟을 사용하여 강판(냉연강판)과 실리콘 웨이퍼 시편에 증착시켰다. 시편은 알코올과 아세톤으로 초음파 세척을 하였으며 진공용기에서 펄스 전원 공급 장치를 이용하여 플라즈마 청정을 약 30분간 실시하였다. 시편 청정이 끝나면 ${\sim}10^{-6}$ Torr 까지 진공 배기를 실시하고, Ar 가스를 진공용기 내로 공급하여 ${\sim}10^{-3}$ Torr로 진공도를 유지하면서 스퍼터링으로 박막 코팅을 실시하였다. 전자석에 전류를 인가하지 않은 시편의 Al 코팅층 밀도는 bulk 밀도의 81%이며 전자석에 역방향 3 A의 전류를 인가시킨 시편의 Al 코팅층 밀도는 bulk 밀도의 약 94%를 보였다. Al 코팅층의 SEM 분석 결과, 스퍼터링 파워 증가에 따라 Al 코팅층 조직에 기공이 많아지고 두께가 증가하는 경향을 보였다. 또한 전자석의 순방향 전류가 증가하면 박막의 두께가 증가하고 치밀도가 낮아지는 반면 전자석의 역방향 전류가 증가할수록 Al 코팅층의 조직은 치밀해졌으며 전자석 전류를 역방향 3 A로 고정하고 스퍼터링 파워를 변화시켜 Al을 코팅하면 타겟 인가전압 1.5 A에서 가장 치밀한 Al 코팅층 조직을 얻을 수 있었다. 가장 치밀한 조직을 갖는 $1.57{\mu}m$의 Al 코팅층은 염수분무 시작 후 약 48시간 후에도 적청이 전면적의 5% 이내로 발생하였다. 마그네트론 스퍼터링법을 이용하여 냉연강판에 Al을 증착하였고 치밀한 조직의 박막을 형성함으로써 냉연 강판의 내식성을 향상할 수 있는 공정기술을 개발하였다.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.259-267
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• 1994

The effect of processing parameters, temperature, gas concentration, gas flow rate and pressure, were studied on the densification of carbon/carbon composites using a Robust design method in isothermal low-pressure chemical vapor infiltration with a gas system of $C_3H_8-N_2$ After one time of isothermal low-pressure chemical vapor infiltrat.ion, the bulk density of carbon/carbon composites in creased up to 1-9% and apparent porosity of the composites decreased down to 20-50%. ANOVA analysis of the experiment.al data revealed that the important parameters of isothermal lowpressure chemical vapor infiltration were temperature, gas concentration and gas flnw rate. 'There was almost no ~ f f e c t on densification by pressure and interaction between each parameters. In t, he present experimental conditions, the highest bulk density was obtained at $1100^{\circ}C$ temperature, 100% $C_3H_8$, concentration, 100 SCCM flow rate and 5 torr pressure.

• 한국석유지질학회:학술대회논문집
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• 2005.09a
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• pp.54-57
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• 2005