Rock Permeability Estimation from Hydraulic Injection Tests in a Sealed Borehole Interval

( Nghiep Q. Quach ),( Yeonguk Jo ),( Chandong Chang ) 대한지질공학회 2018 지질공학 Vol.28 No.1

We propose a borehole test technique to estimate permeability of rocks in borehole. The borehole tests are hydraulic injection tests such as leak-off test and hydraulic fracturing tests, which are originally conducted for stress or casing integrity assessment and not for permeability measurement. We use one-dimensional radial diffusion equation to interpret fluid injection test results in terms of permeability. We apply this technique to a leak-off test conducted at a depth of 700 m in a wellbore, where rock formation is mudstone. The estimated permeability is at an order of 10^-16 m², which is somewhat high but within the range reported for mudstones previously. Quantitative rick assessment suggests that an accurate measurement of open hole section length is important to improve reliability of results. More data may be needed to ensure the reliability of this technique. If validated, however, this technique can provide cost-effective estimation of in situ permeability without conducting independent permeability tests in borehole.

Novel active crack width control technique to reduce the variation on water permeability results for self-healing concrete

Van Mullem, Tim,Gruyaert, Elke,Debbaut, Brenda,Caspeele, Robby,De Belie, Nele Elsevier 2019 Construction & building materials Vol.203 No.-

<P><B>Abstract</B></P> <P>An important characteristic of self-healing concrete is its ability to regain liquid tightness after it has been damaged. This ability can be tested using water permeability setups. However, a lack of standardized test methods makes it difficult to compare results between different studies. Additionally, the large variation on crack widths between specimens results in a large spread of the permeability results. This, together with all other factors (e.g. internal crack geometry) contributing to the variability of permeability results, should be clearly assessed in order to develop a standardized permeability test. In this study a new active crack width control technique has been developed to significantly reduce the variation on the crack width within a series of specimens, resulting in more consistent permeability results. By analysing permeability results of specimens from test series with different nominal crack widths the factors contributing to variability could be assessed. The two main contributors are the variability on the mean crack width at the crack mouth and the variability on the internal crack geometry. The variability of the mean crack width can induce a 3 times higher variability of the permeability results. In contrast to the crack width, the internal geometry of a crack cannot be determined directly, yet it can cause a difference in permeability of more than 25% for specimens with an identical nominal surface crack width. It can be concluded that when crack widths are actively controlled, the main source of variability on permeability results is the internal geometry which cannot be controlled, regardless of the chosen cracking technique. In order to reduce the variance on the mean permeability, it is proposed to use at least six specimens per series.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Variability on permeability is dictated by crack width and internal crack geometry. </LI> <LI> Active crack control can reduce the variability on the crack width significantly. </LI> <LI> If this is done, internal crack geometry governs the variability on permeability. </LI> <LI> A minimum sample size of 6 specimens is proposed when assessing water permeability. </LI> </UL> </P>

피에조 콘 시험과 실내시험을 이용한 양산점토의 투수특성 평가

구남실(Gu, Namsil),김영민(Kim, Youngmin),박재환(Park, Jaehwhan) 한국지반환경공학회 2011 한국지반환경공학회논문집 Vol.12 No.12

점성토 지반의 거동은 압축성뿐만 아니라 투수특성에 크게 영향을 받으며, 특히, 투수특성은 흙의 특성, 이방성에 따라 다르게 나타난다. 투수계수는 주로 실내 압밀시험과 현장 피에조 콘 시험으로부터 산정이 가능하다. 피에조 콘에 의한 투수계수 산정방법은 과잉간극수압의 소산시험 결과로부터 추정할 수 있다. 본 논문에서는 간극수압 소산시험 및 실내시험결과(Oedometer test)를 이용하여 기존의 투수성 평가에 이용되는 이론 해들의 적용성을 검토하고자 하며, 점성토지반 특성에 따른 k_h/ k_υ의 변화를 파악하여 원위치 ?€? ?€?를 합리적으로 추정할 수 있는 적합한 해를 선정하였다. 연구대상지반은 경남 양산물금 지역의 점성토층이며 원위치 시험인 피에조 콘 소산시험과 비교란 시료에 대한 실내압밀시험(Oedometer test)을 실시하고 각 투수계수 추정해 별로 비교?분석을 실시하였다. 연구결과 피에조 콘 소산시험으로 산정된 투수계수비가 5.85로 나타나 실내시험(Rowe cell/Oedometer)으로 산정된 투수계수비 5.28과 매우 유사한 값을 나타냈다. Consolidation behavior of soft clay is generally to be affected by its compressibility and deformation characteristics. Especially, soil permeability depends on soil characteristics including its type of anisotropy. Coefficient of permeability of soft clay is mostly estimated by using laboratory(Oedometer test) and in-stiu piezocone test. The permeability characteristics of soft clay is estimated by excess pore pressure dissipation test results. In this study, the tests were performed to find out the validity of the existing theoretical formula in clay by pore pressure dissipation test and laboratory test results. After grasping of variation the coefficient of permeability ratio(k_h/ k_υ) in different clay soils, it was found out adequate solution of in-stiu permeability ratio(k_h/ k_υ). Piezocone tests and laboratory tests were performed at the site of pilot project of ground improvement at Yangsan-Mulgeum, Gyeongsangnam-do. Comparisons of the estimated values of k_h/ k_υ using piezocone tests results and those from laboratory consolidation tests were carried out. Test results show that values of k_h/ k_υ by piezocone test result(5.85) is similar of it"s laboratory test(5.28).

논문 : 피에조 콘 시험과 실내시험을 이용한 점토지반의 투수특성 연구

구남실 ( Nam Sil Gu ),김영민 ( Young Min Kim ),박재환 ( Jae Hwhan Park ),장지건 ( Ji Guen Jang ) 대한지질공학회 2011 지질공학 Vol.21 No.4

점성토의 압밀거동은 투수성과 변형성에 영향을 받으며 그 중 투수성은 흙의 종류 및 상태, 특히, 이방성에 영향을 받는다. 연약지반의 투수계수는 피에조 콘 소산시험 및 실내압밀시험(Oedometer test)에 의해 구할 수 있으며, 피에조 콘 시험으로 과잉간극수압 소산측정이 가능하여 수평압밀계수와 수평투수계수 평가에 유용하게 사용된다. 본 연구에서는 국내 서해안 및 남해안 지역의 해성 점성토충을 대상으로 피에조 콘 소산시험을 실시하였으며, 불교란 시료에 대한 실내시험(Oedometer, Rowe cell)을 실시하고 각 이론해 별로 비교?분석을 실시하였다. 연구결과 Jamiolkowski(M적용) 등(l985)의 해로 추정한 kh/kv가 이 연구 대상지반의 투수특성과 가장 유사하게 나타나 국내의 연약지반에서 피에조 콘 소산시험 및 실내시험(Oedometer test)에 의하여 투수특성(kh/hv, kh)을 평가하는 방법으로서 이들 이론해의 적용을 추천한다. The consolidation behavior of soft clay is controlled mainly by its compressibility and deformation characteristics. Soil permeability depends on various soil characteristics, including the soil type and anisotropy. The coefficient of permeability of soft clay is determined by using a laboratory test (the Oedometer test) or a piezocone test. The latter test is useful for estimating the permeability characteristics from c(h) and k(h) by performing an excess pore-pressure dissipation test. This study seeks to validate an existing theoretical formula in applying it to marine clay, and to assess the relation between k(h)/k(c) and the mechanical properties of soft clay. Piezocone tests and laboratory tests were performed using sediment from the Yellow Sea and from the South Sea near Korea. We compared k(h)/k(v) values obtained using the piezocone test and using laboratory consolidation tests. The obtained values are similar to the values obtained by Jamiolkowski et al. (M application); therefore, the latter values are recommended to be used as k(h)/k(v).

1D deformation induced permeability and microstructural anisotropy of Ariake clays

Chai, Jinchun,Jia, Rui,Nie, Jixiang,Aiga, Kosuke,Negami, Takehito,Hino, Takenori Techno-Press 2015 Geomechanics & engineering Vol.8 No.1

The permeability behavior of Ariake clays has been investigated by constant rate of strain (CRS) consolidation tests with vertical or radial drainage. Three types of Ariake clays, namely undisturbed Ariake clay samples from the Saga plain, Japan (aged Ariake clay), clay deposit in shallow seabed of the Ariake Sea (young Ariake clay) and reconstituted Ariake clay samples using the soil sampled from the Saga plain, were tested. The test results indicate that the deduced permeability in the horizontal direction ($k_h$) is generally larger than that in the vertical direction ($k_v$). Under odometer condition, the permeability ratio ($k_h/k_v$) increases with the vertical strain. It is also found that the development of the permeability anisotropy is influenced by the inter-particle bonds and clay content of the sample. The aged Ariake clay has stronger initial inter-particle bonds than the young and reconstituted Ariake clays, resulting in slower increase of $k_h/k_v$ with the vertical strain. The young Ariake clay has higher clay content than the reconstituted Ariake clay, resulting in higher values of $k_h/k_v$. The microstructure of the samples before and after the consolidation test has been examined qualitatively by scanning electron microscopy (SEM) image and semi-quantitatively by mercury intrusion porosimetry (MIP) tests. The SEM images indicate that there are more cut edges of platy clay particles on a vertical plane (with respect to the deposition direction) and there are more faces of platy clay particles on a horizontal plane. This tendency increases with the increase of one-dimensional (1D) deformation. MIP test results show that using a sample with a larger vertical surface area has a larger cumulative intruded pore volume, i.e., mercury can be intruded into the sample more easily from the horizontal direction (vertical plane) under the same pressure. Therefore, the permeability anisotropy of Ariake clays is the result of the anisotropic microstructure of the clay samples.

Estimating Rock Permeability from a Leak-off Test and Its Uncertainty

( Nghiep Quach ),( Hyung-mok Kim ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Rock permeability is a fundamental parameter not only to understand underground fluid flow in porous media but also to evaluate geomechanical stability through an effective styress concept such that a realiability of rock permeability estimation is important in cases of injection, production, and charaterizing rock formation. In this study, we apply different approaches such as an analytic approach, numerical analysis, inverse analysis and history matching to estimate and compare rock permeability using a leak-off test. The test, that was carried out at constant flow rate of water injection from surface, was run at 4 m open-hole interval below a casing shoe, where the rock formation is mudstone. The analytic approach here is permeability estimation using a diffusion equation which is known to define a transient fluid flow in porous media, and we could obtain the pressure evolution in the form of Theis's equation by solving the equation in specific conditions. TOUGH2 and iTOUGH2 were used for numerical simulation of the test data and for the estimation of uncertain parameters in terms of inverse analysis, respectively, which solves a mas conservation from multiphase Darcy's flow using an integral finite difference method. nSIGHTS was employed as a history matching approach, which had been developed for a well hydraulic test analysis. From the comparision of permeability estimations, we investigated the uncertainties in estimating formation permeability through demonstrating how differently the estimated permeabilities are obtained depending on diferent approaches and how much a flow model may influence these estimations.

기후변화를 고려한 포장 보조기층의 적정입도분포에 관한 실험연구

최재순(Jaesoon Choi),한누리(Nuri Han) 한국지반환경공학회 2013 한국지반환경공학회논문집 Vol.14 No.7

최근, 시강우량의 최대치의 기록이 매년 바뀌고 있으며 이로 인해 도로의 침수피해 사례가 증가하고 있다. 이러한 이유로 새로운 배수포장체가 개발되고 있으나 보조기층에 대해서는 별도의 고려가 없다. 본 연구에서는 보조기층의 강도와 투수성을 함께 고려한 적정입도분포 기준을 제안하며, 이때 실내실험을 통해 각각의 강도특성 및 투수성을 비교하고자 한다. 실험에 앞서 국내외 보조기층 기준에 대한 시방기준을 토대로 4가지의 대표적인 입도분포를 산정하고 이를 실험하였다. 실험에 있어서 강도특성은 회복 탄성계수 산정을 비교하고, 투수특성은 수직방향의 상향 및 하향 투수계수를 비교하였다. 회복탄성계수 산정은 MR 시험을 통하였으며, 이때 본 연구에서는 진동삼축시험기기를 보완하여 이를 구현하도록 하였다. 투수시험의 경우에는 2가지 투수시험이 수행되었으며, 하향의 흐름에 대한 투수시험으로는 기존의 변수위 투수시험이 적용되었고, 상향의 경우 직경 150mm의 중형 Rowe Cell 투수시험기를 이용하여 시험을 수행하였다. 연구결과, 회복탄성계수와 투수계수의 결과들을 종합하여 포장체 보조기층의 강도특성과 투수 특성을 모두 만족할 수 있는 적정입도분포를 선정하고, 이를 통해 적정입도기준 마련이 가능할 것으로 판단된다. Recently, a top record of hourly-based rainfall has been changed annually and flood damages of road have increased. To solve this problem, pavements for drainage were developed and practically constructed but there was no considerations on sub-base. In this research, we proposed standard for distribution of particle size of sub-base to consider strength characteristic and drainage property. We focused to compare coefficients strength and permeability by laboratory tests. Prior to tests, 4 samples were selected under the consideration on the international or domestic design guideline. In the tests, strength characteristics were compared with resilient modulus. Also, permeability characteristics were compared with coefficient of upward and downward permeability. Resilient modulus was determined with MR test using cyclic triaxial testing system. Two permeability tests were carried out. One is variable head permeability test for downward drainage and the other is Rowe Cell test for upward drainage. In the case of Rowe Cell test, middle-sized sampler with 150mm diameter was used for this study. Consequentially, we tried to find the optimum distribution of particle size to satisfy both of strength and permeability characteristics for sub-base.

An Experimental Investigation on the Stress-strain and Permeability of Chemically Grouted Sands

( Gailing Zhang ),( Yaping Wang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

This paper present an experimental investigation on the stress-strain relationship and permeability of chemically grouted sands during failure process in a triaxial test. The influence of confining pressures, chemical grouts contents, curing time and temperature on permeability and stress-strain characteristics of chemically grouted sands were investigated in the laboratory tests. Moreover, the pore characteristics and the relationship between permeability and deformation failure are also studied by analyzing the results of mercury intrusion porosimetry (MIP) and CT test. The experiment results show that the influence of slurry content on the permeability is obvious, when the slurry content reaches a certain threshold value, the permeability reaches the minimum value. The permeability of chemical grouting sands changed greatly under different confining pressures. Different curing ages have influence on the permeability. When the curing temperature is low, the variation of the permeability is significantly affected by the temperature. When the temperature is high, the influence of the temperature on the permeability coefficient decreases. The effect of strain on permeability coefficient is much smaller than that of confining pressure, slurry content, curing time, curing temperature and other factors. The pores of chemically grouted sand are mainly superpore and macropore with few micropores. The actual case shows that the chemically grouted mass has good durability.

투수성 포장재의 투수특성을 평가하기 위한 시험장비 및 시험절차의 개발

안재훈(Ahn Jae hun),Maricris Jalmasco,신현석(Shin Hyun Suk),정종원(Jung Jong won) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.6

투수성 포장의 적용은 다른 저영향개발 시설과 마찬가지로 유출 증가, 수질 오염, 열섬 현상 등 도시화의 부정적인 영향을 완화하는데 효과적인 것으로 알려져 있다. 본 논문에서는 투수성 포장의 성능 평가를 위한 새로운 시험장비 및 절차를 제시하고, 새로운 방법을 바탕으로 한 시험결과의 예를 보인다. 시험절차는 투수성 포장재에 대한 변수두, 정수두, 폐색 시험을 포함하며, 제안된 시험장비 및 시험절차는 투수성 기층, 보조기층, 혹은 일반 지반재료에도 적용할 수 있다. 각각 최대입경 8 mm와 10 mm의 개립도 골재를 배합한 두 종류의 폴리우레탄 투수성 포장재를 직경 150 mm, 높이 100 mm인 실린더 형태의 시료를 바탕으로 해석하였으며, 변수두 시험의 결과로부터 유출 속도와 동수경사의 관계가 직선형이 아닌 곡선형이라는 것을, 정수두 및 폐색 시험으로부터는 폐색 입자가 10 g이 적용될 때의 유출 속도가 폐색되기 전의 초기 유출 속도의 절반 정도로 감소하고, 폐색 입자가 30 g 이상 적용된 이후에는 유출 속도의 감소 경향이 둔해지는 경향을 나타냈다. Application of permeable pavements helps to alleviate negative impacts of development such as runoff problem, water pollution, and heat island. This paper suggest new test equipment and procedure to assess performance of permeable pavements, and present application examples. The proposed method includes falling head, constant head, and clogging tests, and may apply to permeable bases and soils as well as permeable pavement materials. Two types of polyurethane pavements with maximum aggregate sizes of 8 mm and 10 mm, respectively, were made in cylindrical shapes of 150-mm diameter and 100-mm height, and used for tests. Falling head tests showed that the relationship of discharge velocity and hydraulic gradient is not linear. For both materials, based on constant head and clogging tests, it was investigated that the discharge velocities reduced by half when 10 g of clogging particle was applied, and after applying 30 g of clogging particles, the degradation of velocity became much less severe.

콘크리트의 투수성 측정 및 초저투수성 콘크리트의 개발 연구

오병환,정원기,차수원,장봉석 한국콘크리트학회 1996 콘크리트학회지 Vol.8 No.5

콘크리트의 투수성은 내구성에 커다란 영향을 미치는 요인이 된다. 콘크리트의 강도가 커질수록 투수성은 적어지므로 재래적인 방법으로는 투수 실험이 어렵다. 본 연구에서는 콘크리트의 투수성능향상을 위하여 투수성이 작은 콘크리트에 효과적으로 사용할 수 있는 새로운 투수기법을 연구하고, 투수성이 매우 낮은 초저투수성 콘크리트를 개발하는데 주목적을두고 있다. 이를 위하여 주요 실험변수로서 시멘트의 종류, 단위시멘트량, 혼화재 종류 및 첨가량 그리고 굵은 골재의 최대치수를 주요 변수로 하여 투수성 시험과 가도시험을 포괄적으로 수행하였다. 본 시험 결과 콘크리트의 강도가 증가함에 따라서 콘크리트의 내투수성은 향상됨을 알 수 있으며, 내투수성을 증진하기 위해서는 단위시멘트량의 증가보다는 적절한 혼화재 사용과 그 혼입량을 조절하는 것이 더욱 효과적임을 알 수 있었다. 보통배합의 일반 콘크리트는 투수성이 매우 높은 반면 본 연구에서 제안된 콘크리트는 실리카흄등의 적정 혼입으로 일반 콘크리트의 1/100이하의 매우 낮은 투수성을 보여 초저투수성 콘크리트의 개발이 가능하였다. 본 연구는 앞으로 콘크리트 구조물의 내구성 향상을 위한 중요한 토대를 구축하고 이에 따른 기초자료를 제공할 수 있는 것으로 사료된다. The permeability of concrete influences the durability of concrete remarkably. The conventional test method for permeability is very difficult to apply to high strength concrete because of its very low permeability. The present study employs a resonable and realistic test method for permeability of concrete and proposes a very low permeability concrete. To this end, comprehensive tests have been conducted and major test variables include the types and amount of cement. the types and amount of admixtures, and the size of aggregates. The present test results indicate t h a t the permeability decrease with the increase of strength and that the concrete with certain mineral admixtures exhibits very low permeability. The permeability of those high performance concrete is about 1/100 of conventional normal concrete. The present study provides a firm base for the use of very low permeable and hence very durable concrete.