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Results
Three-Dimensional Modeling of a Coupled Shear-Flow Test on Soft Sedimentary Rock
Park, H. (National Institute of Advanced Industrial Science and Technology (AIST)) | Ito, K. (National Institute of Advanced Industrial Science and Technology (AIST)) | Takahashi, M. (National Institute of Advanced Industrial Science and Technology (AIST)) | Osada, M. (Saitama University) | Smolnik, G. (Silesian University of Technology)
Abstract It is fundamental to understand the process of crack initiation and propagation of intact rock to clarify the coupled hydro-mechanical properties due to the stress change in underground. We have been working on the study of coupled shear-flow properties on sedimentary rock using pumice tuff, Japan. The changes of shear stress, normal stress, flow rate and process of fracturing on sample surface have been investigated by using a new type coupled shear-flow test apparatus. In this study, we designed a numerical model for the coupled shear-flow test using a discrete element code. We report the comparison between the experimental results and the simulation results. The porosity changes of model showed good agreement with the flow rate behavior of the test. 1 Introduction New fractures due to underground excavation or fault cause mechanical and hydrological problems in underground (Tsang et al., 2005, Mitchell and Faulkner, 2009). The fractures are generated through a variety of mechanisms with various scales (Bossart et al., 2002, Scholz et al., 1993). For the research of underground disposal or geological evaluation, it is necessary to investigate the coupled hydro-mechanical behavior of rock (Olsson and Barton, 2001, Li et al., 2008). We conducted an experimental study on coupled shearflow properties of sedimentary rock, and designed a numerical model for the coupled shear-flow test using a three-dimensional simulation tool, PFC3D (Particle Flow Code, Itasca Inc.). The purpose of this study is to examine the performance characteristics of the numerical model. The test system and model are briefly introduced, and the results are compared focusing on stress, permeability and crack propagation. 2 Particle Flow Code PFC3D is classified as a discrete element code (Cundall and Strack, 1979, Potyondy and Cundall, 2004) based on the definition in the review by (Cundall and Hart, 1992). It allows finite displacements and rotations of discrete bodies (including complete detachment), and recognizes new contacts automatically as the calculation progresses. PFC3D can be considered as a simplified implementation of the DEM because of the restriction to rigid spherical particles.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock (0.92)
- Information Technology > CAD (0.41)
- Information Technology > Modeling & Simulation (0.34)
Analysis of the Hydromechanical Behavior of Fault Zones in Petroleum Reservoirs
Righetto, G. L. (ATHENA) | Lautenschläger, C. E. R. (Computational Geomechanics Group, GTEP) | Inoue, N. (Group of Technology in Petroleum Engineering, PUC-Rio) | da Fontoura, S. A. B. (Pontifical Catholic University of Rio de Janeiro)
Abstract Aiming to increase hydrocarbon production, the oil industry has developed recovery methods whose purpose is to get more production. Thus, several problems may be encountered when making use of these techniques, mainly the conventional one. In addition, consideration of geological structures in reservoir engineering, such as fault zones, has fundamental character for determining realistic response for the production of hydrocarbons. In the case of faults zones, its consideration in the model has significant importance currently, especially with regard to the possibility of reactivation and possible loss of tightness of the reservoir. Thus, the aim of this study was assess reservoir models with a fault zone using partially coupled hydro-mechanical simulations. The methodology considers a fault zone whose behavior is given by the Mohr-Coulomb yield criterion. The plasticity model showed consistent results with the process of reactivation for the models. Thus, for the case where the objective is to determine the maximum flow rate of injection as well as its spatial configurations aimed at maintaining the field production, it is possible to establish the flow rate that may result in the initiation of the fault reactivation. Furthermore, the effect of surrounding rocks had a great influence in the time required to initiate the process of reactivation. As a general conclusion, it is stated that the consideration of fault zones in reservoirs, as well as surrounding rocks, must be taken into account to obtain more accurate response to the field behavior. 1 Introduction The exploitation of petroleum began from the drilling of the first well of petroleum in the XIX century in the United States. From this point, aiming increase the petroleum recovery, the oil industry developed recovery methods whose objective is to obtain a higher production than that which would be obtained only as a result of the natural energy of the reservoir (Thomas 2001). In this context, several problems can be faced when one uses recovery techniques, mainly through the fluid injection, in geologically complex reservoirs. Besides that, the consideration of geological structures in the reservoir engineering, for instance faults, has fundamental importance for determining realistic responses related to oil recovery factor, compaction of reservoir, seafloor subsidence, among others. In the specific case of faults, its consideration and analyses has been reported for several authors (Morris et al. 1996, Wiprup & Zoback 2000, Mildren et al. 2002, Streit & Hillis 2004, Chiaramonte et al. 2006, Færseth et al. 2007, Rutqvist et al. 2007, 2008, Soltanzadeh & Hawkes 2008, Zhang et al. 2009, Cappa & Rutqvist 2010, Ducellier et al. 2011, Jain et al. 2012, McDonald et al. 2012; Leclère & Fabbri 2012), due, mainly by its reactivation possibility. In the fault reactivation perspective during the field development, the objective is to prescribe the highest injection flow rate or the highest bottom hole pressure that can be applied in injector wells in order to maintain the reservoir pressure, without the failure of the faults. The process of fault reactivation, due the stress state variation, can result in an emergence of a preferential path for the hydrocarbon, implying in the most critical cases, in the leakage of fluid and possible loss of tightness of the reservoir.
- Geology > Structural Geology > Fault (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.46)
- Oceania > Australia > Western Australia > Bight Basin (0.99)
- Oceania > Australia > South Australia > Great Australian Bight > Bight Basin > Ceduna Basin (0.99)
- Oceania > Australia > South Australia > Bight Basin (0.99)
- Europe > United Kingdom > England > London Basin (0.91)
Abstract The first in Poland, on-line landslide monitoring and warning system has been implemented in 2010 in Polish Carpathians. The Innovative Economy Project financed by European Agency for Regional Development was conducted at selected landslide area in Beskid Niski Mountains. In this area six landslides posed risk for infrastructure, private properties and a new bridge. Mass movements occurred in heavily saturated mixtures of rock-soil weathered deposits over the public road in the river valley. Geotechnical layers were composed mainly of saturated soft clayey soils and claystones interbeded by stiff sandstones. Colluviums depths of 7 to 18m and shallow groundwater level characterized the investigated area. The cumulated displacements up to 193mmwere observed in seven years time. Partial stabilization implemented in 2009 included anchors, surface and internal drainage systems and buttress walls. However, after that time ground movements of 1 to 27mmwere detected in some parts of the landslides. In June 2010, displacements accelerated after extreme precipitations of 100mm in 3 hours time. The new on-line system was consisting of four monitoring stations. Two stations included 3D continuous inclinometers – 60 sensors to the depths of 14 to 16 m. One station included 3 uniaxial in-place sensors, automatic piezometer and groundwater pore pressure transducer. Weather monitoring station performed measurements of precipitation, air pressure, air humidity and air temperature. Data were transferred by GPRS network to the Internet every 10 minutes to 6 hours. The registered displacements depths varied from 12 to 16m depending on localization. They had complicated nature and probably numerous sliding surfaces. Its rates varied from 18 to 38mm in last 30 months. Special software for data interpretation and recognition of high-risk conditions was implemented to allow sending SMS alarm messages to the road owner. Real-time monitoring may allow better recognition of landslide activation factors.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.54)
- Geology > Geological Subdiscipline > Geomechanics (0.37)
Feasibility and Behavior of a Full Scale Disposal Cell in a Deep Clay Layer
Morel, J. (Andra, Meuse/Haute Marne Underground Research Laboratory) | Bumbieler, F. (Andra, Meuse/Haute Marne Underground Research Laboratory) | Conil, N. (Andra, Meuse/Haute Marne Underground Research Laboratory) | Armand, G. (Andra, Meuse/Haute Marne Underground Research Laboratory)
Abstract At the Meuse/Haute Marne Underground Research Laboratory, Andra is studying the possibility of disposal for intermediate to high level activity – long life nuclear waste in a 500m deep clay formation. In particular, a specific technical and scientific program is carried out for several years to test the feasibility of realization and the behavior of disposal cells for high level – long life waste packages. Within the framework of this program, and as part of the European project LUCOEX (Large Underground Concept Experiment), a new phase has started at the end of 2012 with the realization of a full scale disposal cell demonstrator. Heat generated by waste packages is simulated by electrical heaters over a length of 15 m, with the aim to reach 90?C at the cell interface in 2 years. The thermo-mechanical behavior of the cell as well as the THM impact on the surrounding rock is monitored through a very complete instrumentation. 1 Introduction 1.1 General context Andra, the French national radioactive waste management agency, is in charge of the study on the possibility of disposal for intermediate to high level activity – long life (IL/HL – LL) nuclear waste in deep geological repositories. In this aim, the Meuse/Haute Marne Underground Research Laboratory (URL) has been excavated since 2000 in a 500m deep claystone layer (Callovo-Oxfordian, COX) to characterize to confining properties of the clay-stone and demonstrate the feasibility of construction and operation of a geological disposal (Delay et al. 2007). 1.2 Callovo-Oxfordian claystones The main level of the URL is excavated at a depth of 490m in the middle of a 135m thick argillaceous rock layer, overlain and underlain by poorly permeable carbonate formations. Argillaceous rock contains a mixture of clay minerals (40 to 45% on average) and clay-size fraction of other compositions. The clay minerals offer groundwater tightness and radionuclides retention. Silica and carbonate-rich sedimentary components contribute to high strength of the rock and stability of the underground construction. Table 1 gives Callovo-Oxfordian claystones mechanical characteristics. Sedimentation has led to a slightly anisotropic behavior of claystones. In-situ measurements indicate a strong coupling between mechanical and hydraulic processes (Armand et al. 2011).
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (1.00)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Water & Waste Management > Solid Waste Management (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Power Industry > Utilities > Nuclear (0.74)
- North America > United States > Texas > Permian Basin > Central Basin > Cox Field (0.97)
- Europe > United Kingdom > England > London Basin (0.91)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.87)
- Health, Safety, Environment & Sustainability > Environment > Waste management (0.68)
- Health, Safety, Environment & Sustainability > Environment > Naturally occurring radioactive materials (0.68)
Thermal Conductivity of Rocks under High Pressure Conditions
Lin, W. (Japan Agency for Marine-Earth Science and Technology (JAMSTEC)) | Tadai, O. (MarinWorks Japan LTD.) | Hirose, T. (Japan Agency for Marine-Earth Science and Technology (JAMSTEC)) | Tanikawa, W. (Japan Agency for Marine-Earth Science and Technology (JAMSTEC)) | Kinoshita, M. (Japan Agency for Marine-Earth Science and Technology (JAMSTEC)) | Mukoyoshi, H. (MarinWorks Japan LTD.) | Takahashi, M. (National Institute of Industrial Science and Technology (AIST))
Abstract To exactly evaluate thermal conductivity of a rock specimen taken from a great depth, pressure effects have to be taken into consideration. We developed a new measurement system of thermal conductivity of rock specimens under high confining pressure and high pore-fluid pressure. This system consists of a commercial thermal conductivity meter, a high pressure vessel in which the rock specimen, sensors of thermal conductivity measurements were installed and two high resolution syringe pumps. One of the syringe pumps is for controlling confining pressure; and the other is for pore-fluid pressure. Both the pumps are able to monitor fluid flow rate and cumulative volume change of pore fluid in rock specimen assembly during testing. We examined the effects of high pressure on thermal conductivity in rock specimens of five terrestrial rock types. Thermal conductivity clearly increased with increasing effective pressure for both dry and wet (water saturated) samples. 1 Introduction In case of the geological disposal of high-level radioactive waste at a large depth in underground, thermal conductivity of rocks under in-situ pressure and temperature conditions is the most important key parameter for estimations of temperature increasing of the rocks around the canisters associated to generation of heat by radioactive materials. The physical properties of rocks, including thermal conductivity, are dependent on pressure and temperature (Schön 1998), so in situ pressure and temperature conditions should be simulated in laboratory measurements of the thermal conductivity of drill core samples from great depths. General, thermal conductivity of rock samples are measured at atmospheric pressure condition in civil and geotechnical engineering fields. Several previous studies on thermal conductivity at high confining pressure were found in mining and geoscience fields (e.g. Horai and Susaki 1989; Abdulagatova et al. 2009), but almost of them did not take pore-fluid pressure into consideration. We developed a new apparatus capable of measuring the thermal conductivity of a rock sample at both high confining pressure and high pore-fluid pressure conditions based on our previous system which was able to measure the thermal conductivity under high confining pressure condition only (Lin et al. 2011).