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Results
Abstract Re-Injection is one of the most important methods to dispose fluid associated with oil and natural gas production. Disposed fluids include produced water, hydraulic fracture flow back fluids, and drilling mud fluids. Several formation damage mechanisms are associated with the injection including damage due to filter cake formed at the formation face, bacteria activity, fluid incompatibility, free gas content, and clay activation.
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Escondido Formation (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- (2 more...)
- Well Drilling > Formation Damage (1.00)
- Well Drilling > Drilling Fluids and Materials (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- (4 more...)
Abstract Rock masses are inherently variable in their nature owing to the complex interrelationship between discontinuities and intact rock. The simplest way to account for this uncertainty is through the explicit modelling of the spatial heterogeneity. This is commonly conducted through stochastic simulation, where multiple realizations of studied attributes are produced. Within this paper a geostatistics-based approach to modelling spatial uncertainty which is new to the field of open pit mine design is presented. The method is based on the use of sequential Gaussian simulation to reproduce the spatial heterogeneity observed in studied attributes. The paper presents the formal methodology used for stochastic simulation and the results obtained from the modelling process. Models were constructed by stochastically varying the geological strength index and uniaxial compressive strength within a geomechanical simulation model of the Ok Tedi mine site in Papua New Guinea. Simulations demonstrate the importance of understanding the scale dependent characteristics of sample variance and the effects of spatial heterogeneity on both the critical SRF and projected failure size.
- North America > United States (1.00)
- Oceania (0.89)
- North America > Canada > British Columbia > Metro Vancouver Regional District (0.28)
- Geology > Rock Type > Sedimentary Rock (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.90)
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Abstract Crushed salt is being considered as a backfilling material to place around nuclear waste within a salt repository environment. In-depth knowledge of salt thermal and mechanical properties as it reconsolidates is critical to thermal and mechanical modeling of the reconsolidation process. An experimental study was completed to quantitatively evaluate the thermal conductivity of consolidated crushed salt as a function of porosity. Temperature dependence of this thermal conductivity was also determined. Porosities ranged from 1% to 40%, and temperatures ranged from ambient up to 300°C. This range of conditions is expected to more than cover those that might be encountered in a radioactive waste disposal facility. Two different experimental devices were used to measure these values. The thermal conductivity of reconsolidated crushed salt decreases with increasing porosity or increasing temperature; conversely, salt thermal conductivity increases as the salt consolidates. Thermal conductivity of experimentally deformed bedded salt cores was shown to be related to fracture density, as a type of porosity. Crushed salt for this study came from the Waste Isolation Pilot Plant (WIPP). Salt was observed to dewater during heating, and the weight loss from dewatering was quantified. A simple mixture theory model is presented to represent the data developed in this study.
- Europe (1.00)
- North America > United States > New Mexico (0.29)
- Water & Waste Management > Solid Waste Management (1.00)
- Energy > Power Industry > Utilities > Nuclear (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.69)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (22 more...)
Steady State-Creep of Rock Salt - Improved Approaches for Lab Determination and Modeling to Describe Transient, Stationary and Accelerated Creep, Dilatancy and Healing
Günther, R.-M. (Institute for Geomechanics GmbH (IfG)) | Salzer, K. (Institute for Geomechanics GmbH (IfG)) | Popp, T. (Institute for Geomechanics GmbH (IfG)) | Lüdeling, C. (Institute for Geomechanics GmbH (IfG))
Abstract Actual problems in geotechnical design, e.g. of underground openings for radioactive waste repositories or high-pressure gas storages, require sophisticated constitutive models and consistent parameters for rock salt that facilitate reliable prognosis of stress-dependent deformation and associated damage from the initial excavation to long times. Fortunately in the long term the response of salt masses is governed by its steady state creep behavior. However, because in experiments the time necessary to reach true steady creep rates can last time periods of some few days to years, depending mainly on temperature, an innovative but simple creep testing approach is suggested. A series of multi-step tests with loading and un-loading cycles allow a more reliable estimate of stationary creep rates in a reasonable time schedule. In completion, the advanced strain-hardening approach of Günther/Salzer is used which describes all relevant deformation properties of rock salt, e.g. creep and damage induced rock failure, comprehensively within the scope of an unified creep approach. The capability of the combination of improved creep testing procedures and accompanied modelling is demonstrated by recalculating multi-step creep at different loading and temperature conditions. Thus reliable extrapolations relevant to in-situ creep rates (10 to 10 s) become possible.
- North America > United States (1.00)
- Europe (0.68)
- Geology > Mineral > Halide > Halite (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
Abstract A very slow creep test was performed on an Avery island salt sample. The testing device was set in a remote gallery of the Varang&*#233;ville Mine to take advantage of the very stable temperature there. This multi-step test was 30-month long. The applied load was 0.1, 0.2 and 0.3 MPa, successively. Steady-state strain rates are of the order of 10-12 s-1, significantly faster than what can be extrapolated from creep tests performed under larger load, Rates are an increasing function of the applied load.
- Europe (0.48)
- North America > United States (0.46)
Abstract We present in this paper two examples on two different scales (in borehole and regional), in which stress magnitudes might be influenced by the presence of fractures and faults. Hydraulic fracturing in situ stress measurements conducted in a borehole showed a large fluctuation of the maximum horizontal principal stress (SHmax) at an order of ~10 MPa over few tens of meter depth. Numerous wide aperture fractures are abundant around depths where S Hmax are relatively low, whereas such fractures are scarce at depths where S Hmax are relatively high. Such wide fractures are oriented optimally for slip under the in situ stress condition, playing a role of limiting stress magnitudes by slippage along the fractures and consequent release of excessive stress. A similar observation was made at a much larger scale. Collected stress data in Gyeongsang Basin, Korea show inhomogeneous horizontal stresses with their magnitudes varying laterally. The lateral variation of horizontal stress magnitudes appears to be related to regional scale fault density. This result also suggests that excessive stress might possibly be released by slippage along faults. This study demonstrates that stress magnitudes can be constrained by natural fractures and faults quite locally (at a scale of few tens of meters) and also quite regionally (over km scales).
- North America > United States (0.94)
- Asia (0.67)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics (0.48)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- Asia > South Korea > Gyeongsang Basin (0.99)
- North America > United States > Utah > Island Field (0.97)
Geomechanical Modeling of Repositories for Nuclear Waste Disposal In Rock Salt Formations
Fahland, S. (Federal Institute for Geosciences and Natural Resources (BGR)) | Heusermann, S. (Federal Institute for Geosciences and Natural Resources (BGR)) | Schäfers, A. (Federal Institute for Geosciences and Natural Resources (BGR))
Abstract The safety assessment of radioactive waste repositories in salt formations requires geomechanical model calculations to analyze the stability of the repository mine and to predict the long-term integrity of the rock salt barrier. Important steps of this analysis are the geological exploration and modeling, the definition of material models and determination of related parameters, the geomechanical and numerical modeling as well as the specification of appropriate criteria to evaluate the numerical results. Two stress-based criteria are considered for rock salt: The dilatancy criterion and the frac criterion. As an example, the geomechanical integrity of the salt barrier in the southern part of the Morsleben repository, Germany, is investigated. Dilatant zones in the rock salt only occur directly around the rooms of the repository; sufficient areas of the salt barrier show no dilatancy even for long time periods. If backfilling of the repository rooms is taken into account, the frac criterion is satisfied too.
- Geology > Mineral > Halide > Halite (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Water & Waste Management > Solid Waste Management (1.00)
- Energy > Power Industry > Utilities > Nuclear (0.71)
- Energy > Oil & Gas > Upstream (0.71)
Lateral Reinforcement of Fully Grouted Roof Bolts in a FLAC3D Simulated Coal Mine Entry
Murphy, M.M. (National Institute for Occupational Safety and Health (NIOSH)) | Esterhuizen, G.S. (National Institute for Occupational Safety and Health (NIOSH)) | Tulu, I.B. (National Institute for Occupational Safety and Health (NIOSH))
Abstract Fully grouted roof bolts increase the stability of a bedded mine roof by providing resistance to both vertical and horizontal displacements. The bolts provide suspension reinforcement from axial loads and lateral reinforcement from shear resistance effects. The lateral reinforcement provided by a roof bolt is difficult to observe in the field, but is often suggested by observation of roof failure cavities. However, these observations do not indicate whether bolt shear failure precedes or is a result of collapse. This paper highlights the use of a well-calibrated FLAC3D numerical model to investigate the shear resistance provided by a fully grouted bolt. The study first looks at analytical solutions to determine the necessary element size to obtain appropriate deflections of thin beams within FLAC3D. The study then compares different models demonstrating that the shear resistance provided by a fully grouted bolt has a limited impact on the overall stability of the mine roof. The model results indicate that the axial suspension effects of fully grouted bolts are more significant than the lateral reinforcement provided.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.48)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.46)
- Government > Regional Government > North America Government > United States Government (0.69)
- Materials > Metals & Mining > Coal (0.46)
Abstract During horizontal well stimulation from an array multiple perforations it is difficult to ensure simultaneous growth of all hydraulic fractures (HF) in the array due to a phenomenon known as stress shadowing, which favors the growth of the less constrained outer fractures in the array. Recently, using a fully coupled, parallel-planar 3D HF model it has been shown that it is possible to alleviate the localization effect of stress shadowing by appropriately breaking the symmetry of the perforation array. This procedure was termed interference fracturing due to the way in which the nearest neighbors to the outer fractures are positioned to interrupt the localization and runaway growth of the outer fractures. In this paper we will explore the robustness of the positioning of the interference fractures on a configuration designed to expose the changes to the dynamics of this complex fully-coupled system affected by perturbations to the initiation points in the array.
Abstract Modeling of the interaction between the bits cutters and rock is crucial in the rate of penetration (ROP) drilling simulators which simulate the bits performance under different conditions. This paper first analyzes the mechanism of rock failure by roller cone bit’s inserts and PDC cutters. Next, the drill bit performance software based on the interaction mechanism is introduced. Applying the software, series of simulation tests on the rock breaking process by the tricone inserts and the PDC cutters have been carried out. The entire process of an insert and PDC cutter interacting with rock, from initial contact to leaving the bottom rock, is simulated. The results show that the software can simulate the interaction between drill bit cutters and rock very well. The contact area on each insert is plotted, from which we can see which part of the insert is more easily worn out. This will help the bit design engineers improve insert shape designs. The simulated loads on the cutters are analyzed and compared. The software can also predict ROP, which can be used to optimize and improve drilling efficiency.
- North America > United States (0.95)
- North America > Canada > Alberta (0.16)