• 지질공학
• /
• 제29권4호
• /
• pp.367-381
• /
• 2019

We investigate pore pressure conditions and reservoir compaction associated with oil and gas production using 3 different permeability models, which are all based on one-dimensional radial flow diffusion model, but differ in considering permeability evolution during production. Model 1 assumes the most simplistic constant and invariable permeability regardless of production; Model 2 considers permeability reduction associated with reservoir compaction only due to pore pressure drawdown during production; Model 3 also considers permeability reduction but due to the effects of both pore pressure drawdown and coupled pore pressure-stress process. We first derive a unified stress-permeability relation that can be used for various sandstones. We then apply this equation to calculate pore pressure and permeability changes in the reservoir due to fluid extraction using the three permeability models. All the three models yield pore pressure profiles in the form of pressure funnel with different amounts of drawdown. Model 1, assuming constant permeability, obviously predicts the least amount of drawdown with pore pressure condition highest among the three models investigated. Model 2 estimates the largest amount of drawdown and lowest pore pressure condition. Model 3 shows slightly higher pore pressure condition than Model 2 because stress-pore pressure coupling process reduces the effective stress increase due to pore pressure depletion. We compare field data of production rate with the results of the three models. While models 1 and 2 respectively overestimates and underestimates the production rate, Model 3 estimates the field data fairly well. Our result affirms that coupling process between stress and pore pressure occurs during production, and that it is important to incorporate the coupling process in the permeability modeling, especially for tight reservoir having low permeability.

• 한국지반신소재학회논문집
• /
• 제7권4호
• /
• pp.47-55
• /
• 2008

본 연구에서는 제주도와 같이 투수성이 매우 높은 지반에서의 침투량을 산정하기 위하여 침투트렌치에 대한 모형시험 및 현장시험을 실시하였다. 모형실험결과를 토대로 비침투량 산정식을 제안하였다. 제안된 식에 의해 산정된 침투량은 기존식에 의해 산정된 침투량보다 약 2배 정도 크게 나타났다. 한편, 현장침투시험을 통해 얻어진 침투량을 제안식과 기존식에 의해 얻은 침투량과 비교 한 결과, 현장침투시험을 통해 얻은 침투량은 제안식에 의해 얻은 침투량과 거의 비슷하게 나타났다. 따라서 투수성이 높은 조립토 지반에 설치된 침투트렌치의 침투량을 산정함에 있어 본 연구에서 제안된 침투량 산정식을 적용하는 것이 타당하다.

• BMB Reports
• /
• 제28권2호
• /
• pp.184-190
• /
• 1995

Functional study of the gap junction channel has been hindered by its inaccessibility in situ. Identification of forms of this channel in artificial membrane has been elusive because of the lack of identifying channel physiology. Connexin32 forms gap junction channels between neighboring cells in rat liver. Connexin32 was affinity-purified using a monoclonal antibody and reconstituted into artificial phospholipid vesicles. The reconstituted connexin32 formed channels through the vesicle membrane that were permeable to sucrose (Stokes radius: $5{\AA}$). The permeability to sucrose was reversibly reduced by acidic pH. In addition, the pH effect on the permeability to sucrose fit well with by the Hill's equation (where, n=2.7 and pK=6.7).

• Journal of the Korean Wood Science and Technology
• /
• 제36권5호
• /
• pp.49-55
• /
• 2008

This study was carried to investigate the effects of steaming and four different drying methods on the longitudinal liquid permeability of Korean pine (Pinus koraiensis Sieb.et Zucc.) board. Four drying methods were air drying, conventional kiln drying, microwave-vacuum drying and high temperature drying. Darcy equation was used for calculating the specific permeability of the small sapwood specimens taken from the treated boards while capillary rising method was used for the heartwood specimens. The sapwood specimens were extracted with water and benzene-alcohol solution to examine the mechanism of liquid flow in treated wood. No significant correlation was found between specific permeability and the number of resin canals of the sapwood specimens. Extraction decreased the differences of specific permeabilities of the sapwood specimens between the five treatment methods. The effects of extraction on the longitudinal permeability are different between five treatments. The fluid path in heartwood was observed by dynamic observation method.

• 펄프종이기술
• /
• 제33권1호
• /
• pp.62-62
• /
• 2001

The cigarette ventilation affects not only the amount of tar and nicotine delivery by a cigarette, but also the composition of the smoke. Therefore, it is important to stabilize of variability in cigarette ventilation that would be affected by changes in cigarette components. This work was conducted to determine the major factors that influence the cigarette ventilation and also to provide fundamental informations for improving the uniformity of cigarette performances. To evaluate the effect of cigarette ventilation as a dependant variable, the three independent factors were the air permeability of plugwrap, tipping paper and the filter pressure drop. We determined the effect of paper permeability on ventilation variability and the optimum condition in combinations of independent factors. The mean of cigarette ventilation was increased as plugwrap permeability increases, particularly at 26,000 CU. However, it was exhibited that standard deviation and coefficient of variation of the cigarette ventilation were decreased with increasing plugwrap permeability. At the 600 CU and 1,200 CU of tipping paper permeability, process capability index (Cp) of the cigarette ventilation increased as plugwrap permeability increases. Following the optimum condition of cigarette ventilation induced by fitted regression equation, one was to optimize 50% ventilation level is by combination with plugwrap permeability of 16,000 CU, tipping paper permeability of 810 CU, filter pressure drop of 319 mm$H_2O$, respectively.

• 지질공학
• /
• 제29권3호
• /
• pp.303-314
• /
• 2019

얕은 대수층에서 매우 복잡한 함양과정을 거치는 지하수의 함양은 지표와 지하매질의 투수성에 의해 상당한 영향을 받는다. 투수성은 고유투수계수(intrinsic permeability)와 수리전도도(hydraulic conductivity)의 두 가지 개념으로 설명되며 이중 지표매질의 특성만으로 수리전도도를 구하려는 많은 연구가 이루어졌다. 본 연구에서는 경주지역 지하수기초조사에서 수행된 미고결퇴적물의 입도분포곡선과 강우-지하수위 교차상관분석을 토대로 회귀식을 사용하여 강우-지하수위 교차상관분석을 통한 수리전도도 산정식을 제안하고 실제현장에서 수행한 대수성 시험결과와 비교하여 그 적용성을 검토하였다. 그 결과 사질토 기반 충적층대수층에서 Zunker의 경험식에서 산정된 수리전도도와 강우-지하수위 최대 교차상관계수의 상관식이 자연로그형태로 증가하면서 결정계수 0.95 이상으로 매우 큰 상관성을 나타내었고 이 회귀식을 다른 관측공에 적용한 결과 실제 현장에서 수행한 대수성시험 결과와 평균제곱근오차가 2.83%로 나타나 강우-지하수위 모니터링 자료만으로 매우 신뢰할 만한 수리전도도를 추정할 수 있었다.

• Journal of applied mathematics & informatics
• /
• 제29권5_6호
• /
• pp.1269-1283
• /
• 2011

Here we consider magneto-convection in a mushy layer which is formed during solidification of binary alloys. The mushy layer is treated as an active porous media with variable permeability. The equations governing the layer are conservation of mass, conservation of heat, conservation of solute, magnetic induction equation, momentum equation governed by the Darcy's law and Maxwell's equations for the magnetic field. To study the second order effects on the flow without solving the second order system, we need to obtain the adjoint system for the flow. This motivates the authors we derive the adjoint system analytically for the mushy layer case. Numerical results of the adjoint system are presented for passive and active mushy layers at the onset of the motion using a set of parameters experimentalists use.

• Smart Structures and Systems
• /
• 제17권2호
• /
• pp.327-345
• /
• 2016

The existence of SH-wave in a piezomagnetic layer overlying an initially stressed orthotropic half-space is investigated. The coupled of differential equations are solved for piezomagnetic layer overlying an orthotropic elastic half-space. The general dispersion equation has been derived for both magnetically open circuit and magnetically closed circuits under the four types of boundary conditions. In the absence of the piezomagnetic properties, initial stress and orthotropic properties of the medium, the dispersion equations reduce to classical Love equation. The SH-wave velocity has been calculated numerically for both magnetically open circuit and closed circuits. The effect of initial stress and magnetic permeability are illustrated by graphs in both the cases. The velocity of SH-wave decreases with the increment of wave number.

• 지질공학
• /
• 제18권1호
• /
• pp.27-36
• /
• 2008

이 연구는 토질특성을 평가하는 주요 영향인자인 투수계수를 몇 가지 토질물성만으로 쉽게 산정할 수 있도록 단순회귀 분석을 이용하여 투수계수산정모델을 개발하였다. 이를 위한 연구지역은 강원도 평창군 진부면지역으로 총 45개 지점에서 토층시료를 채취하여 실내에서 여러 토질시험을 실시하였다. 상관분석을 통해 시험결과들 중 투수계수에 유효한 토질인자를 선별한 후 선별된 인자들과 직접투수시험에 의한 투수계수간의 관계를 단순회귀분석으로 공식화한 투수계수산정모델을 개발하였다. 또한, 개발된 투수계수산정모델과 직접투수시험 및 각 경험식들에 의한 투수계수를 비교 분석하여 모델의 적합성을 검증하였다. SPSS(statistical package for the social sciences)를 이용하여 여러 토질물성과 투수계수간의 상관관계를 분석한 결과 유효경, 간극비, 건조단위중량이 투수계수에 가장 크게 영향을 미치는 토질인자인 것으로 나타났다. 투수계수 산정모델에 의한 투수계수는 직접투수시험에 의한 투수계수와 거의 유사한 결과를 보였다. 따라서 개발된 투수계수산정모델은 연구지역과 같은 토질조건인 경우 토층의 투수계수 산정을 위한 모델로 이용이 가능할 것으로 사료된다.

• Geomechanics and Engineering
• /
• 제25권2호
• /
• pp.159-170
• /
• 2021

Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.