Hydrogeological challenges in a low carbon economy

Hydrogeology has traditionally been regarded as the province of the water industry, but it is increasingly finding novel applications in the energy sector. Hydrogeology has a longstanding role in geothermal energy exploration and management. Although aquifer management methods can be directly applied to most high-enthalpy geothermal reservoirs, hydrogeochemical inference techniques differ somewhat owing to peculiarities of high-temperature processes. Hydrogeological involvement in the development of ground-coupled heating and cooling systems using heat pumps has led to the emergence of the sub-discipline now known as thermogeology. The patterns of groundwater flow and heat transport are closely analogous and can thus be analysed using very similar techniques. Without resort to heat pumps, groundwater is increasingly being pumped to provide cooling for large buildings; the renewability of such systems relies on accurate prediction and management of thermal breakthrough from reinjection to production boreholes. Hydrogeological analysis can contribute to quantification of accidental carbon emissions arising from disturbance of groundwater-fed peatland ecosystems during wind farm construction. Beyond renewables, key applications of hydrogeology are to be found in the nuclear sector, and in the sunrise industries of unconventional gas and carbon capture and storage, with high temperatures attained during underground coal gasification requiring geothermal technology transfer

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 192

This bibliography lists 247 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1979

Shale Gas Roundtable: Deliberations, Findings, and Recommendations

In response to the desire of regional, multi-sector leaders to elevate and inform the regional energy dialogue, the Shale Gas Roundtable was created in the fall of 2011 to fulfill a three-part mission related to unconventional oil and gas production, transport, and use: Building and sustaining relationships among relevant cross-sector stakeholders to better support diverse regional environmental protection, community quality of life, and economic development goals; Identifying high-priority focus areas through consensus-building dialogue, extensive research, and shared goals for the region; and Assessing the focus areas and developing ideas and recommendations that promote the improved management of and outcomes from regional unconventional oil and gas development

The Impact of Formation and Fracture Properties Alternations on the Productivity of the Multi-stage Fractured Marcellus Shale Horizontal Wells.

As the reservoir deplete, the pore pressure decreases and the effective stress increases. The increase in the effective stress results in the formation compaction which can alter the formation and hydraulic fracture properties. This is particularly significant for a Marcellus shale horizontal well with multi-stage hydraulic fracture due to low Young\u27s modulus and moderate Poisson\u27s ratio of the Marcellus shale. The degree of the effective stress increase depends on the initial productivity of the well, which is influenced by the hydraulic fracture properties, formation properties, as well as the operating conditions. Therefore, it is necessary to couple the geomechanical and fluid flow simulations to accurately predict the gas production from a horizontal Marcellus Shale well with multi-stage fractures. The objective of this study was to investigate the impact of the formation mechanical properties (Young\u27s modulus and Poisson\u27s ratio), the hydraulic fracture properties (half-length, initial conductivity, and spacing), as well as operating conditions (wellbore pressure) on the productivity of a horizontal Marcellus Shale well with multi-stage fractures. The advanced technical information available from the Marcellus Shale horizontal wells located at the Marcellus Shale Energy and Environment Laboratory (MSEEL) site provided an opportunity to investigate the impact of the shale compressibility on gas production. The core, well log, well test, completion, stimulation, and production data from the wells at the MSEEL site were utilized to estimate the shale mechanical and petrophysical properties as well as the hydraulic fracture characteristics. The results of the data analysis were then utilized to develop a reservoir model for a horizontal well completed in Marcellus Shale with multi-stage hydraulic fractures. A geomechanical (Mohr-Coulomb) module was coupled with reservoir model to determine the effective stress distribution and the formation compaction and its impact on the shale porosity. The impact of the shale compaction on the permeability for both matrix and fissure, and the conductivity of the hydraulic fractures were determined from the Marcellus shale core plug analysis as well as the published measurements on the propped fracture conductivity in Marcellus shale and were incorporated in the reservoir model. The inclusion of the compressibility impacts in the reservoir model provided a more realistic simulated production profile. The gas recovery was found to be negatively impacted by the formation compaction due to the increase in the effective stress. The reduction in the conductivity of the hydraulic fractures due to the compressibility impact was found to have the most adverse effect on the gas recovery. The compressibility impacts were found to be more severe during the early production due to higher production rates. Finally, the model was employed to investigate the impact of the formation’s mechanical properties, hydraulic fracture properties, and the operating conditions on the gas recovery. The higher values of Young’s modulus and Poisson\u27s ratio can mitigate the compressibility impacts and lead to higher recovery. Conversely, the higher values of the fracture half-length as well as the closer fracture spacing will amplify the adverse impacts of the compressibility on the early gas recovery. However, the adverse impacts diminishes with time. The higher values of the initial hydraulic fracture conductivity can also mitigate the compressibility impacts

Doctor of Philosophy

dissertationFluid production from tight and shale gas formations has increased significantly, and this unconventional portfolio of low-permeability reservoirs accounts for more than half of the gas produced in the United States. Stimulation and hydraulic fracturing are critical in making these systems productive, and hence it is important to understand the mechanics of the reservoir. When modeling fractured reservoirs using discrete-fracture network representation, the geomechanical effects are expected to have a significant impact on important reservoir characteristics. It has become more accepted that fracture growth, particularly in naturally fractured reservoirs with extremely low permeability, cannot be reliably represented by conventional planar representations. Characterizing the evolution of multiple, nonplanar, interconnected and possibly nonvertical hydraulic fractures requires hydraulic and mechanical characterization of the matrix, as well as existing latent or healed fracture networks. To solve these challenging problems, a reservoir simulator (Advanced Reactive Transport Simulator (ARTS)) capable of performing unconventional reservoir simulation is developed in this research work. A geomechanical model has been incorporated into the simulation framework with various coupling schemes and this model is used to understand the geomechanical effects in unconventional oil and gas recovery. This development allows ARTS to accept geomechanical information from external geomechanical simulators (soft coupling) or the solution of the geomechanical coupled problem (hard coupling). An iterative solution method of the flow and geomechanical equations has been used in implementing the hard coupling scheme. The hard coupling schemes were verified using one-dimensional and two-dimensional analytical solutions. The new reservoir simulator is applied to learn the influence of geomechanical impact on unconventional oil and gas production in a number of practical recovery scenarios. A commercial simulator called 3DEC was the geomechanical simulator used in soft coupling. In a naturally fractured reservoir, considering geomechanics may lead to an increase or decrease in production depending on the relationship between the reservoir petrophysical properties and mechanics. Combining geomechanics and flow in multiphase flow settings showed that production decrease could be caused by a combination of fracture contraction and water blockage. The concept of geomechanical coupling was illustrated with a complex naturally fractured system containing 44 fractures. Development of the generalized framework, being able to study multiphase flow reservoir processes with coupled geomechanics, and understanding of complex phenomena such as water blocks are the major outcomes from this research. These new tools will help in creating strategies for efficient and sustainable production of fluids from unconventional resources

Prediction and Simulator Verification of Roll/Lateral Adverse Aeroservoelastic Rotorcraft–Pilot Couplings

The involuntary interaction of a pilot with an aircraft can be described as pilot-assisted oscillations. Such phenomena are usually only addressed late in the design process when they manifest themselves during ground/flight testing. Methods to be able to predict such phenomena as early as possible are therefore useful. This work describes a technique to predict the adverse aeroservoelastic rotorcraft–pilot couplings, specifically between a rotorcraft’s roll motion and the resultant involuntary pilot lateral cyclic motion. By coupling linear vehicle aeroservoelastic models and experimentally identified pilot biodynamic models, pilot-assisted oscillations and no-pilot-assisted oscillation conditions have been numerically predicted for a soft-in-plane hingeless helicopter with a lightly damped regressive lead–lag mode that strongly interacts with the roll modeat a frequency within the biodynamic band of the pilots. These predictions have then been verified using real-time flight-simulation experiments. The absence of any similar adverse couplings experienced while using only rigid-body models in the flight simulator verified that the observed phenomena were indeed aeroelastic in nature. The excellent agreement between the numerical predictions and the observed experimental results indicates that the techniques developed in this paper can be used to highlight the proneness of new or existing designs to pilot-assisted oscillation

Casing structural integrity and failure modes in a range of well types: a review.

This paper focus on factors attributing to casing failure, their failure mechanism and the resulting failure mode. The casing is a critical component in a well and the main mechanical structural barrier element that provide conduits and avenue for oil and gas production over the well lifecycle and beyond. The casings are normally subjected to material degradation, varying local loads, induced stresses during stimulation, natural fractures, slip and shear during their installation and operation leading to different kinds of casing failure modes. The review paper also covers recent developments in casing integrity assessment techniques and their respective limitations. The taxonomy of the major causes and cases of casing failure in different well types is covered. In addition, an overview of casing trend utilisation and failure mix by grades is provided. The trend of casing utilisation in different wells examined show deep-water and shale gas horizontal wells employing higher tensile grades (P110 & Q125) due to their characteristics. Additionally, this review presents casing failure mixed by grades, with P110 recording the highest failure cases owing to its stiffness, high application in injection wells, shale gas, deep-water and high temperature and high temperature (HPHT) wells with high failure probability. A summary of existing tools used for the assessment of well integrity issues and their respective limitations is provided and conclusions drawn

Emergency Resource Layout with Multiple Objectives under Complex Disaster Scenarios

Effective placement of emergency rescue resources, particularly with joint suppliers in complex disaster scenarios, is crucial for ensuring the reliability, efficiency, and quality of emergency rescue activities. However, limited research has considered the interaction between different disasters and material classification, which are highly vital to the emergency rescue. This study provides a novel and practical framework for reliable strategies of emergency rescue under complex disaster scenarios. The study employs a scenario-based approach to represent complex disasters, such as earthquakes, mudslides, floods, and their interactions. In optimizing the placement of emergency resources, the study considers government-owned suppliers, framework agreement suppliers, and existing suppliers collectively supporting emergency rescue materials. To determine the selection of joint suppliers and their corresponding optimal material quantities under complex disaster scenarios, the research proposes a multi-objective model that integrates cost, fairness, emergency efficiency, and uncertainty into a facility location problem. Finally, the study develops an NSGA-II-XGB algorithm to solve a disaster-prone province example and verify the feasibility and effectiveness of the proposed multi-objective model and solution methods. The results show that the methodology proposed in this paper can greatly reduce emergency costs, rescue time, and the difference between demand and suppliers while maximizing the coverage of rescue resources. More importantly, it can optimize the scale of resources by determining the location and number of materials provided by joint suppliers for various kinds of disasters simultaneously. This research represents a promising step towards making informed configuration decisions in emergency rescue work

International Developments in the Field of Unconventional Gas and Oil Extraction: Update 2017

The last few years have witnessed a wealth of studies, reports and assessments being published in many EU member states, by national and international organisations and in the research community on economic, environmental and human health related aspects of unconventional oil and gas exploration and production. Many R&D initiatives are also underway. This report attempts to provide a survey of several of such studies and initiatives, with a focus on the years 2015, 2016 and early 2017. Principally, reports and studies from public bodies and scientific institutes were covered. Additionally, several papers published in peer-reviewed journals were included. A review of the quality of the studies covered, the accuracy of their claims and their possible limitations was not carried out. This report is therefore only meant to provide a compilation of their summaries, without any endorsement of the findings reported in any of the studies and assessments covered in the report.JRC.C.3-Energy Security, Distribution and Market