Hydraulic Fracturing Mine Back Trials — Design Rationale and Project Status

Last year, a joint Mining and Oil & Gas industry consortium was established in Canada to conduct hydraulic fracturing (HF) tests accompanied by a mine-back of fractured regions to assess HF models and microseismic monitoring data during controlled experiments. Details about the displacement field, fracture aperture and extent, and micro-seismic parameters could then be verified and used as calibration data for modeling of HF processes in igneous and dense sedimentary rocks

A non-local plasticity model of stimulated volume evolution during hydraulic fracturing

The final publication is available at Elsevier via https://doi.org/10.1016/j.ijsolstr.2018.09.023� 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Hydraulic fracturing in naturally fractured rocks often leads to the creation of a stimulated zone in which the target rock formation is deformed and fractured by the reactivation and shear dilation of natural fractures and the plastic deformation, damaging, and fracturing of the bulk. In this paper, we present a novel mathematical model with the goal of simulating the evolution of the stimulated volume during hydraulic fracturing. This was achieved by introducing an equivalent continuum non-local poro-elastic-plastic zone of enhanced permeability for the stimulated region, characterized by an internal length scale. The non-local plastic constitutive behavior of the rock, combined with the classical Biot�s poroelastic theory, was implemented using a new implicit C0 non-local finite element method. A predictor-corrector return algorithm for the non-local plasticity model was formulated as an extension of the classical plasticity algorithm. To improve the performance of the iterative solution scheme, a consistent algorithmic stiffness tangent modulus was developed. First, the elastic-plastic constitutive behavior of the proposed methodology is verified using the standard non-porous biaxial compression test with strain softening behavior. Next, it is verified that the poro-elastic-plastic model correctly simulates the evolution of the stimulated zone and the subsequent change in the flow and fluid pressure for several hydraulic fracturing examples under various far-field in-situ stress conditions. Lastly, the non-local poro-elastic-plastic model is shown to be mesh-independent and capable of capturing a wide range of complex fracturing behavior.Natural Sciences and Engineering Research Council of Canad

Data Analytics Techniques for Performance Prediction of Steamflooding in Naturally Fractured Carbonate Reservoirs

Thermal oil recovery techniques, including steam processes, account for more than 80% of the current global heavy oil, extra heavy oil, and bitumen production. Evaluation of Naturally Fractured Carbonate Reservoirs (NFCRs) for thermal heavy oil recovery using field pilot tests and exhaustive numerical and analytical modeling is expensive, complex, and personnel-intensive. Robust statistical models have not yet been proposed to predict cumulative steam to oil ratio (CSOR) and recovery factor (RF) during steamflooding in NFCRs as strong process performance indicators. In this paper, new statistical based techniques were developed using multivariable regression analysis for quick estimation of CSOR and RF in NFCRs subjected to steamflooding. The proposed data based models include vital parameters such as in situ fluid and reservoir properties. The data used are taken from experimental studies and rare field trials of vertical well steamflooding pilots in heavy oil NFCRs reported in the literature. The models show an average error of <6% for the worst cases and contain fewer empirical constants compared with existing correlations developed originally for oil sands. The interactions between the parameters were considered indicating that the initial oil saturation and oil viscosity are the most important predictive factors. The proposed models were successfully predicted CSOR and RF for two heavy oil NFCRs. Results of this study can be used for feasibility assessment of steam flooding in NFCRs..

A comprehensive study of geothermal heating and cooling systems

The final publication is available at Elsevier via https://doi.org/10.1016/j.scs.2018.09.036� 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Geothermal heat is an energy source that is local, reliable, resilient, environmentally-friendly, and sustainable. This natural energy is produced from the heat within the earth, and has different applications, such as heating and cooling of buildings, generating electricity, providing warm/cold water for agricultural products in greenhouses, and balneological use. Geothermal energy is not dependent on weather or climate and can supply heat and electricity almost continuously throughout the year. It may even be possible to use geothermal projects as �thermal batteries�, wherein waste or collected heat is stored for future use, even seasonal use, making geothermal energy �renewable� at a time scale of years. Extensive research has been carried out on different technologies and applications of geothermal energy, but comprehensive assessment of geothermal heating and cooling systems is relevant because of changing understanding, scale of application, and technology evolution. This study presents a general overview of geothermal heating and cooling systems. We provide an introduction to energy and the environment as well as the relationship between them; a brief history of geothermal energy; a discussion of district energy systems; a review of geothermal heating and cooling systems; a survey of geothermal energy distribution systems; an overview of ground source heat pumps; and, a discussion of ground heat exchangers. Recognition and accommodation of several factors addressed and discussed in our review will enhance the design and implementation of any geothermal heating or cooling system

Rock Engineering Applications

xi, 431 hlm.; Ind,; 24 c

Simulation of Real Defect Geometry and Its Detection Using Passive Magnetic Inspection (PMI) Method

Reinforced concrete is the most commonly used material in urban, road, and industrial structures. Quantifying the condition of the reinforcing steel can help manage the human and financial risks that arise from unexpected reinforced concrete structure functional failure. Also, a quantitative time history of reinforcing steel condition can be used to make decisions on rehabilitation, decommissioning, or replacement. The self-magnetic behavior of ferromagnetic materials is useful for quantitative condition assessment. In this study, a ferromagnetic rebar with artificial defects was scanned by a three-dimensional (3D) laser scanner. The obtained point cloud was imported as a real geometry to a finite element software platform; its self-magnetic behavior was then simulated under the influence of Earth&rsquo;s magnetic field. The various passive magnetic parameters that can be measured were reviewed for different conditions. Statistical studies showed that 0.76% of the simulation-obtained data of the rebar surface was related to the defect locations. Additionally, acceptable coincidences were confirmed between the magnetic properties from numerical simulation and from experimental outputs, most noticeably at hole locations

Seismicity and the State of Stress in the Dezful Embayment, Zagros Fold and Thrust Belt

This study focuses on determining the orientation and constraining the magnitude of present-day stresses in the Dezful Embayment in Iran’s Zagros Fold and Thrust Belt. Two datasets are used: the first includes petrophysical data from 25 wells (3 to 4 km deep), and the second contains 108 earthquake focal mechanisms, mostly occurring in blind active basement faults (5 to 20 km deep). Formal stress inversion analysis of the focal mechanisms demonstrates that there is currently a compressional stress state (Aφ=2.0–2.2) in the basement. The seismologically determined SHmax direction is 37° ± 10°, nearly perpendicular to the strike of most faults in the region. However, borehole geomechanics analysis using rock strength and drilling evidence leads to the counterintuitive result that the shallow state of stress is a normal/strike-slip regime. These results are consistent with the low seismicity level in the sedimentary cover in the Dezful Embayment, and may be evidence of stress decoupling due to the existence of salt layers. The stress state situation in the field was used to identify the optimally oriented fault planes and the fault friction coefficient. This finding also aligns with the prediction Coulomb faulting theory in that the N-S strike-slip basement Kazerun Fault System has an unfavorable orientation for slip in a reverse fault regime with an average SW-NE SHmax orientation. These results are useful for determining the origin of seismic activity in the basin and better assessing fault-associated seismic hazards in the area