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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Tunnel and Underground Space
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Journal DOI :
Korean Society for Rock Mechanics
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Volume & Issues
Volume 23, Issue 6 - Dec 2013
Volume 23, Issue 5 - Oct 2013
Volume 23, Issue 4 - Aug 2013
Volume 23, Issue 3 - Jun 2013
Volume 23, Issue 2 - Apr 2013
Volume 23, Issue 1 - Feb 2013
Selecting the target year
Regional Distribution Pattern and Geo-historical Transition of In-situ Stress Fields in the Korean Peninsula
Synn, Joong-Ho ; Park, Chan ; Lee, Byung-Joo ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 457~469
DOI : 10.7474/TUS.2013.23.6.457
We have analyzed the regional in-situ stress pattern using 460 stress measurement data at about 100 test sites in Korea, and suggested correlation equations of stress-depth and stress ratio-depth. We made Korea Stress Map(KSM) as in-situ stress fields of the Korean peninsula, combining with a paleo-stress analysis according to the geological period and a stress estimation from focal mechanism. We confirmed the reliability and applicability of correlation equations derived in this study, comparing with worldwide stress-depth patterns, and also estimated the pattern of in-situ stress fields of north-eastern Asia including Korea, China and Japan, comparing with World Stress Map.
Study on Hydraulic Fracturing in Transverse Isotropic Rock Using Bonded Particle Model
Jung, Jaewoong ; Heo, Chan ; Jeon, Seokwon ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 470~479
DOI : 10.7474/TUS.2013.23.6.470
Hydraulic fracturing is used as a method for promoting the fluid flow in the rock and, in the energy field such as geothermal development and the development of sales gas, many studies has been actively conducted. In many cases, hydraulic fracturing is not performed in isotropic rock and especially in the case of sedimentary rocks, hydraulic fracturing is conducted in the transverse isotropic rock. The direction of the crack growth on hydraulic fracturing does not necessarily coincides with the direction of maximum principal stress in the transverse isotropic rock. Therefore, in this study, bonded particle model with hydro-mechanical coupling analysis was adopted for analyzing the characteristics of hydraulic fracturing in transverse isotropic rock. In addition, experiments of hydraulic fracturing were conducted in laboratory-scale to verify the validity of numerical analysis. In this study, the crack growth and crack patterns showed significant differences depending on the viscosity of injection fluid, the angle of bedding plane and the influence of anisotropy. In the case of transverse isotropic model, the shear crack growth due to hydraulic fracturing appeared prominently.
Development of Round Trip Occurrence Simulator Considering Tooth Wear of Drill Bit
Lee, Seung Soo ; Kim, Kwang Yeom ; Shin, Hyu-Soung ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 480~492
DOI : 10.7474/TUS.2013.23.6.480
After the introduction of geothermal power generation technology based on engineering reservoir creation that can be applied on non-volcanic region, industrial need for studies on the efficient and economic execution of costly deep-depth drilling work becomes manifest increasingly. However, since it is very difficult to predict duration and cost of boring work with acceptable reliability because of many uncertain events during the execution, efficient and organized work management for drilling is not easily achievable. Especially, the round trip that discretely occurs because of the abrasion of bit takes more time as the depth goes deeper and it has a great impact on the work performance. Therefore, a technology that can simulate the occurrence timing and depth of round trip in advance and therefore optimize them is essentially required. This study divided the abrasion state of bit into eight steps for simulation cases and developed a forecast algorithm, i.e., TOSA which can analyze the depth and timing of round trip occurrence. A methodology that can divide a unit section for simulation has been suggested; while the Bourgoyne and Young model has been used for the forecast of drilling rates and bit abrasion extent by section. Lastly, the designed algorithm has been systemized for the convenience of the user.
Particle Based Discrete Element Modeling of Hydraulic Stimulation of Geothermal Reservoirs, Induced Seismicity and Fault Zone Deformation
Yoon, Jeoung Seok ; Hakimhashemi, Amir ; Zang, Arno ; Zimmermann, Gunter ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 493~505
DOI : 10.7474/TUS.2013.23.6.493
This numerical study investigates seismicity and fault slip induced by fluid injection in deep geothermal reservoir with pre-existing fractures and fault. Particle Flow Code 2D is used with additionally implemented hydro-mechanical coupled fluid flow algorithm and acoustic emission moment tensor inversion algorithm. The output of the model includes spatio-temporal evolution of induced seismicity (hypocenter locations and magnitudes) and fault deformation (failure and slip) in relation to fluid pressure distribution. The model is applied to a case of fluid injection with constant rates changing in three steps using different fluid characters, i.e. the viscosity, and different injection locations. In fractured reservoir, spatio-temporal distribution of the induced seismicity differs significantly depending on the viscosity of the fracturing fluid. In a fractured reservoir, injection of low viscosity fluid results in larger volume of induced seismicity cloud as the fluid can migrate easily to the reservoir and cause large number and magnitude of induced seismicity in the post-shut-in period. In a faulted reservoir, fault deformation (co-seismic failure and aseismic slip) can occur by a small perturbation of fracturing fluid (<0.1 MPa) can be induced when the injection location is set close to the fault. The presented numerical model technique can practically be used in geothermal industry to predict the induced seismicity pattern and magnitude distribution resulting from hydraulic stimulation of geothermal reservoirs prior to actual injection operation.
EGS Power Generation and Hydraulic Stimulation
Min, Ki-Bok ; Song, Yoonho ; Yoon, Woon-Sang ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 506~520
DOI : 10.7474/TUS.2013.23.6.506
While geothermal energy provides the only base-load power among renewable energy sources, its development has been carried out predominantly in volcanic area. EGS (Enhanced Geothermal System) is a ubiquitous technology that can allow the geothermal power generation virtually in any area. This manuscript introduces the current state-of-the-art of EGS development in the world and presents the hydraulic stimulation technology and associated microseismicity which are key technical component in EGS. Finally this paper suggests the key research areas required in Korea for further development of EGS.
Effect of Ground Vibration on Surface Structures and Human Environments -Application of Blasting Vibration to Induced Seismicity in EGS Hydraulic Stimulation-
Lee, Chung-In ; Min, Ki-Bok ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 521~537
DOI : 10.7474/TUS.2013.23.6.521
While microseismicity induced by hydraulic stimulation carried out for EGS is useful means in estimating the range of permeability increase, it also affect surface structures and environments. In order to establish a mitigation plan for microseismicity triggered by hydraulic stimulation, we reviewed world-wide guidelines on the impact of ground vibration on the surface structure and human environment by blasting. Case studies from Europe and USA on the microseismicity by hydraulic stimulation are presented and suggestions are made for the guidelines on ground vibration by hydraulic stimulation for the ongoing Pohang EGS project.
Theoretical Background and Design of Hydraulic Fracturing in Oil and Gas Production
Cheon, Dae-Sung ; Lee, Tae Jong ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 538~546
DOI : 10.7474/TUS.2013.23.6.538
This paper deals with a hydraulic fracturing technique, which is one of the methods to maximize the recovery rate and productivity of oil and gas in the petroleum industry. In the hydraulic fracturing, typically water mixed with sand and chemicals is injected into a wellbore in order to create artificial fractures along which formation fluids migrate to the well. In recent years, it is widely used in non-conventional oil and gas such as oil shale and shale gas. Three main stages of the hydraulic fracturing process, the proposed design models for the effective hydraulic fracturing and diagnostics after fracturing treatment are introduced. In addition, this paper introduces reservoir geomechanics to solve various problems in the process of hydraulic fracturing.
Case Studies of Enhanced Geothermal System: Fenton Hill in USA and Hijiori in Japan
Park, Eui-Seob ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 547~560
DOI : 10.7474/TUS.2013.23.6.547
The importance of renewable energy has increased continuously due to the energy insecurity and the necessity of reducing carbon dioxide which is causing global climate change. In such a situation, the Pohang Enhanced Geothermal System (EGS) power plant project which is launched in December 2010 shall be a new opportunity for the development of EGS related technologies in Korea. In this paper, the case studies of Fenton Hill project in the USA and Hijiori project in Japan are introduced in order to help a part of the domestic EGS demonstration project. As a result, it could be helpful to minimize the trial and error of the domestic EGS project by acquiring the achievements and limitations of existing EGS projects.
Enhanced Geothermal System Case Study: The Soultz Project
Lee, Tae Jong ; Song, Yoonho ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 561~571
DOI : 10.7474/TUS.2013.23.6.561
Various experiences on enhanced geothermal system (EGS) has been accumulated from the Soultz project through various scientific experiments and research activities for more than 20 years since it started in the year of 1984 until the 1.5 MW Organic Rankine Cycle (ORC) binary power plant has been built up in Soultz-sous-
area, France. They have been applied to Cooper basin in Australia, Landau and Insheim in Germany and so forth. This report summaries the experiences from Soultz in the aspect of artificial reservoir creation, expecting to be helpful for reducing any trial and errors or unnecessary expenses in ongoing Korean EGS project in Pohang area, where the geological features are similar to Soultz area.
Case Study of Microseismic Management Systems for Basel EGS Project
Lee, Sangdon ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 572~580
DOI : 10.7474/TUS.2013.23.6.572
In this case study, I examined the microseismic safety management system of Deep Heat Mining Basel (DHMB) as EGS Geothermal Project which was conducted in Basel, Switzerland. EGS Geothermal Power projects which require induced seismic event by stimulation for creation of EGS geothermal reservoir have to be controlled pressure and flow rate of stimulation by establishment of microseismic safety management system. Traffic light system and Communication response procedure of DHMB project to respond step by step corresponding microseismic event intensity through continuous monitoring during stimulation period have been managed and established in advance of stimulation. However, the project was discontinued because of an earthquake to occur larger than expected one due to post-injection seismicity occurring in the geothermal reservoir after completion of injection for stimulation. The result of post analysis, Real-time traffic light system was verified to need a establishment of new microseismic safe management system to be considered post-injection seismicity phenomenon.
Overview of Geothermal Energy Projects in Europe and the GEISER Project on Induced Seismicity
Yoon, Jeoung Seok ; Bruhn, David ; Zang, Arno ;
Tunnel and Underground Space, volume 23, issue 6, 2013, Pages 581~592
DOI : 10.7474/TUS.2013.23.6.581
This article provides an overview on the geothermal energy research in Europe and one of the EU funded projects `GEISER (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs)` in which the authors were involved. More details are given for description of GEISER, in particular, about aims and discussions and how the project was managed. Emphasis is given to one of the work packages `Induced Seismicity and Large Magnitude Events (LME)` and results of this work package are summarized. This article intends to summarize the lessons learned in the GEISER project and give recommendations to future geothermal projects by creating Enhanced Geothermal Systems hydraulic stimulation where induced seismicity issues are expected to be a major issue and obstacle.