Proceedings 56th US Rock Mechanics / Geomechanics Symposium最新文献

{"title":"Strength effects of microfracture on granular microstructures evaluated by FDEM direct numerical simulation","authors":"T. Hagengruber","doi":"10.56952/arma-2022-2209","DOIUrl":"https://doi.org/10.56952/arma-2022-2209","url":null,"abstract":"We present results of an investigation into the mechanisms of damage in granular microstructures conducted through direct numerical simulation with the combined Finite-Discrete Element Method (FDEM). Scanning Electron Microscope (SEM) images of a pressed crystalline powder are directly meshed, resolving grain-grain interfaces. Semi-ductile microfracture is simulated by prescribing a combination of inter-granular brittle fracture and intra-granular grain plasticity. Pristine (undamaged) and damaged microstructures are simulated in uniaxial compression tests and compared to experimental uniaxial compression measurements from literature. The simulation results show that the observed microscale mechanisms of damage (microfracture predominantly around and sometimes through grains and crack associated pore-growth) can well explain degradation of strength observed in the laboratory measurements. A method of tracing grain boundaries from SEM images is described and applied to meshing of a microstructure damaged through cyclic thermal loading. By calibrating the simulations to the damaged and undamaged experimental measurements, micro-mechanical/structural insight is gained into the mechanisms of damage for the material. The results show that the SEM-based micro-characterization of damage can explain the degradation in effective strength observed in the testing and can be accurately modeled using the presented methods.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129190602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On averaging of toughness heterogeneity when modelling hydraulic fracture evolution","authors":"M. Dutko, G. da Fies, D. Peck, Gennady Mishuris","doi":"10.56952/arma-2022-0262","DOIUrl":"https://doi.org/10.56952/arma-2022-0262","url":null,"abstract":"In this paper we describe various approaches used to capture heterogeneity within the reservoir undergoing hydraulic fracturing treatment and their implication on modelling of fracture propagation. In highly laminated reservoirs with soft and/or weak layers, capturing heterogeneity at an appropriate resolution is the key for successful prediction fracture growth and other crucial treatment parameters. Our focus is on studying several strategies to average fracture toughness and assess their suitability for use in advanced computational methods such as FE/BEM. In practice the well log and petrophysical data deduced from various measurements and observations are upscaled and/or homogenized to the spatial approximation size. The fracture toughness is one of the most delicate physical parameters and application of the homogenization techniques are rather uncertain, hence any proposed averaging will depend on process conditions and the toughness distribution. We propose and analyse a notion of an average toughness and show that it is a process dependent variable and provide some recommendations how to implement the defined measure into the numerical modelling. As an example, we use periodic distributions and consider model without leak off that allows us straightforward handling different regimes (toughness/viscosity).","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126068403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comprehensive Constitutive Model Solver","authors":"J. Chieslar","doi":"10.56952/arma-2022-0038","DOIUrl":"https://doi.org/10.56952/arma-2022-0038","url":null,"abstract":"The object-oriented software concept is applied to material mechanics calculations. The result is a comprehensive predictor-corrector which has been employed to solve virtually all of the constitutive exercises in a mature, general-purpose, finite element program. In addition to updating internal variables consistent with global inputs (corrector), the software also produces consistent material tangents (corrector), without resort to formulae. Coupled mechanical-thermal-porous flow problems are addressed as well as compound mechanical responses: creep-plasticity, creep-damage, etc. Material and spatial coordinate transformations are incorporated as well as transformation to and from local material axes. Internal calculations may be undertaken in either spatial or material coordinates, depending upon the native definition. Even viscoelasticity and hyper-viscoelasticity, via Prony series, are efficiently handled by the sparse solver. A tool to exercise any material model, simulating global inputs, is incorporated. Historical plots may be produced and inputs may be cyclical or otherwise simulate complex histories. This is accomplished by using PostScript operators.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122870560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Determination of Poroelastic Properties of Utah FORGE Rocks","authors":"Xuejun Zhou, A. Ghassemi","doi":"10.56952/arma-2022-0526","DOIUrl":"https://doi.org/10.56952/arma-2022-0526","url":null,"abstract":"In this paper we present the results of a laboratory experimental study to measure the poroelastic properties of Utah FORGE reservoir rock. The target formations are granite and granodioritic rocks of low permeability so that the determination of their poroelastic properties is particularly challenging. In this work, we present the measurements of the Biot’s effective coefficient α and the Skempton’s B. The measurements on α are made by using strain gauges by following two different approaches: (1) α =1-K/Ks, K is the drained bulk modulus and Ks the grain bulk modulus; (2) α =-K/H, in which H is the so-called poroelastic expansion coefficient. These approaches yield two sets of data which can be compared. The Skempton’s B measurement is based on the equation α=dPp/dPc(undrained condition), i.e., the ratio between pore pressure change and confining pressure change under an undrained condition, and distilled water is used as the pore fluid. The test results show that both the Biot’s coefficient and Skempton’s B are all stress dependent and decrease with the increase of the effective stress. Furthermore, we observe that the Biot’s coefficient falls in the range of [0.5, 1) rather than [0, 1) for many different types of rock, including the rock samples in this research.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121278695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction Method of Cutting Settling Velocity in Gas-liquid Two-phase Flow Based on Multi-gene Genetic Programming","authors":"Zhaopeng Zhu, Xianzhi Song, Liang Han, Rui Zhang, W. Liu, Jiasheng Fu, Xiaoli Hu, Dayu Li, Furong Qin, Donghan Yang","doi":"10.56952/arma-2022-0439","DOIUrl":"https://doi.org/10.56952/arma-2022-0439","url":null,"abstract":"The cuttings settling process becomes erratic in the complex gas-liquid mixture under gas kick, it is very difficult to accurately describe the migration process of cuttings. Meanwhile, the traditional empirical formula based on fitting experimental data is difficult to accurately predict the complex cuttings settlement. Neural network and other intelligent models with high prediction accuracy are difficult to be popularized and applied due to their black box properties. Multi-gene genetic programming can accurately describe complex nonlinear problems and automatically optimize the structure and parameters of the mathematical model, so as to effectively reduce the complexity of the model. Based on the multi-gene genetic programming algorithm, this study used a variety of input parameters to predict the settling velocity, explored the relationship between the input variables and the result, and established an explicit mathematical model of settling velocity with RMSE of 0.0896 in test set and R2 of 0.9292, which breaks the accuracy limits of traditional empirical model and the inexplicability of neural network model. This new method for predicting cuttings settling velocity in gas-liquid mixture can provide theoretical guidance for efficient cuttings migration in wellbore during gas kick.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128911848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative study on enhanced oil recovery effect of amphiphilic nanomaterials - Experiment and mechanism Investigation","authors":"Erdong Yao, Yuan Li, Bojun Li, Lianqi Sheng, Kun Zhang, Guolin Yu, Fu-jian Zhou","doi":"10.56952/arma-2022-0178","DOIUrl":"https://doi.org/10.56952/arma-2022-0178","url":null,"abstract":"Due to the transcendental property of nanoparticle, nanoparticle fluid flooding becomes one of the enhanced oil recovery (EOR) technique, which had played a significant role in tight oil exploitation in the worldwide scale recent years. In particular, the amphiphilic nanomaterials can greatly increase the oil recovery.To provide some guidance in selecting nanomaterials for flooding, 3 kinds of amphiphilic nanomaterials, including silicon dioxide (SiO2), graphene oxide (GO) and molybdenum disulfide (MoS2), are chosen to serve as object of the study. In lab, the physical properties were systematically characterized and flooding was conducted. Further, the morphology character of nanomaterials was placed extra emphasis and the mechanisms of EOR were also studied. The purpose was to find the link between the morphology of nanomaterials and EOR. Flooding experiment revealed that MoS2 were able to enhance the oil recovery by approximately 11%, which were better that of the others. From the above, it can be inferred that spherical materials have a “point-to-surface” contact at multiphase interfaces, while sheet materials can achieve a “surface-to-surface” contact with a higher interfacial activity. In addition, the film-climbing characteristics of amphiphilic nanomaterials were found in the experiment, which may be one of the potential reasons for enhanced oil recovery.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133792110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stratigraphic Analysis of Microseismic Signatures during Hydraulic Stimulation","authors":"N. Welch, M. Gross, Lianjie Huang, S. Glubokovskikh","doi":"10.56952/arma-2022-0549","DOIUrl":"https://doi.org/10.56952/arma-2022-0549","url":null,"abstract":"This paper presents a novel workflow to enhance the interpretation of microseismic events by comparing the temporal evolution of the microseismic cloud between adjacent stages from two different wells stages. The stratigraphic properties of identified rock layers along with changes within the local stress field distribution were used to determine the propagation path and aperture of the hydraulic fracture. Hydraulic fractures however are largely aseismic, and thus identified microseismic signatures surrounding the hydraulic fracture may indicate important surrounding damage-zone fracture formation. A comparison of each microseismic event and towith the local rock stratigraphy of the loci determined certain regions where rock composition and larger formation layers influenced the moicroseismic signals of events. This analysis allowed for the classification of microseismic events by formation layers and can elicit different in-situ stress states during hydraulic stimulation. Principal Component Analysis of each formation microseismic cloud can quickly show dominating stresses in the microseismic signals. The changes in the microseismic cloud between the first and second stimulated and second wells during a zipper hydraulic fracture stimulations shows the significant changes in formation stress from one well to another in a multi-well system.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128161344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The EGS Collab Project – Stimulations at Two Depths","authors":"Timothy J Kneafsey, P. Dobson, C. Ulrich, V. Rodríguez Tribaldos, Y. Guglielmi, D. Blankenship, P. Schwering, M. Ingraham, J. Burghardt, M. White, T. Johnson, C. Strickland, V. Vermeul, H. Knox, J. Morris, P. Fu, Megan Smith, Hui Wu, J. Ajo-Franklin, Lianjie Huang, G. Neupane, R. Horne, W. Roggenthen, J. Weers, T. Doe, T. Pyatina","doi":"10.56952/arma-2022-0448","DOIUrl":"https://doi.org/10.56952/arma-2022-0448","url":null,"abstract":"The EGS Collab project, supported by the US Department of Energy, is performing intensively monitored rock stimulation and flow tests at the 10-m scale in an underground research laboratory to address challenges in implementing enhanced geothermal systems (EGS). Data and observations from the field tests are compared to simulations to understand processes and build confidence in numerical modeling of the processes. Experiment 1 examined hydraulic fracturing in a well-characterized fractured phyllite 1.5 km deep at the Sanford Underground Research Facility (SURF). Testbed characterization included fracture mapping, borehole acoustic and optical televiewers, full waveform sonic, conductivity, resistivity, temperature, campaign p- and s-wave investigations and electrical resistance tomography. Borehole geophysical techniques including passive seismic, continuous active source seismic monitoring, electrical resistance tomography, fiber-based distributed strain, distributed temperature, and distributed acoustic monitoring, were used to carefully monitor stimulation events and flow tests. More than a dozen stimulations and nearly one year of flow tests were performed. Quality data and detailed observations were collected and analyzed during stimulation and water flow tests, and these data are available. We achieved adaptive control of the tests using real-time monitoring and rapid dissemination of data and near-real-time simulation. Experiment 2 examines the potential for hydraulic shearing in amphibolite 1.25 km deep at SURF. The testbed consists of nine subhorizontal boreholes, four of which surround the testbed with grouted-in ERT, seismic sensors, CASSM and distributed fiber sensors. The test wells include a “five-spot” set with an injection well and four production/monitoring wells. Like Experiment 1, the testbed was characterized geophysically and hydrologically, and three stimulations have been performed using new tools.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125684365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding Salt Mine Ground Behavior through Geotechnical Monitoring and Data Analysis","authors":"Shay A Gregory","doi":"10.56952/arma-2022-0611","DOIUrl":"https://doi.org/10.56952/arma-2022-0611","url":null,"abstract":"The Waste Isolation Pilot Plant (WIPP) was constructed for the permanent disposal of defense-generated transuranic waste from DOE sites around the United States. WIPP functions as a category 4 mine and category 2 nuclear facility. The waste is to be deposited 660 m (2150 ft) beneath the Earth’s surface inside of the Delaware Basin salt bed for permanent disposal. The first waste shipment arrived at WIPP in 1999 and is currently anticipated to operate beyond 2050. Due to the creeping nature of salt and the hazards involved in handling nuclear waste, it is paramount to monitor the changing conditions of the mine. Throughout the WIPP’s project life, geotechnical and mining engineers have developed and improved upon the data collection methods, instrumentation, and analysis that is required to monitor the ground movement in this unique salt mine. Using forecasting methods, WIPP’s geotechnical engineering team has predicted several ground falls and provides support to the site’s mining endeavors. A review of the historical ground movement data collection methods and analysis is given, as well as examples of ground falls and geotechnical abnormalities. In addition, ongoing application of operations research and engineering statistics will be discussed.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131576224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat propagation through fractures during hydraulic stimulation in crystalline rock","authors":"Q. Wenning, N. Gholizadeh Doonechaly, A. Shakas, F. Serbeto, F. Bethmann, B. Dyer, R. Castilla, P. Meier, M. Hertrich, H. Maurer, D. Giardini, S. Wiemer","doi":"10.56952/arma-2022-0381","DOIUrl":"https://doi.org/10.56952/arma-2022-0381","url":null,"abstract":"The Bedretto Underground Laboratory for Geosciences and Geoenergies (BULGG) is located in central Switzerland and serves as a test bed for geothermal energy research. Several boreholes were drilled from the laboratory section (ca. 1.1 km overburden) to serve as injection boreholes for stimulation and geophysical monitoring boreholes. During a hydraulic stimulation injection in winter 2020 into injection borehole ST2 interval ranging from 313 to 320 m, we observe a thermal perturbation using distributed fiber optic temperature sensing in a neighboring open borehole (MB1) at a depth of 275 m to 295 m. Prior to injection, there is a thermal anomaly in MB1 at about 289 m due to natural fracture fluid flow. Below this depth the temperature is approximately 1.5 °C higher than above. During injection there is a gradual upward movement of the thermal anomaly to ca. 278 m depth. After injection is stopped, the thermal signal gradually recovers to the original depth. The cause for such a temperature change is potentially due to increased warm water flow reaching the base of MB1 from deeper ST2 or poro-elastic fracture closure of the cold-water conducting fractures at 278 and 289 m depth in MB1 during stimulation.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133125563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}