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Optimized three-dimensional (3D) fracture networks are crucial for multistage hydrofracturing. To better understand the mechanisms controlling potential disasters as well as to predict them in 3D multistage hydrofracturing, some governing factors, such as fluid injection-induced stratal movement, compression between multiple hydraulic fractures, fracturing fluid flow, fracturing-induced microseismic damaged and contact slip events, must be properly simulated via numerical models. This study aims to analyze the stratal movement and microseismic behaviours induced by multistage propagation of 3D multiple hydraulic fractures.

Adaptive finite element–discrete element method was used to overcome the limitations of conventional finite element methods in simulating 3D fracture propagation. This new approach uses a local remeshing and coarsening strategy to ensure the accuracy of solutions, reliability of fracture propagation path and computational efficiency. Engineering-scale numerical models were proposed that account for the hydro-mechanical coupling and fracturing fluid leak-off, to simulate multistage propagation of 3D multiple hydraulic fractures, by which the evolution of the displacement, porosity and fracture fields, as well as the fracturing-induced microseismic events were computed.

Stratal movement and compression between 3D multiple hydraulic fractures intensify with increasing proximity to the propagating fractures. When the perforation cluster spaces are very narrow, alternate fracturing can improve fracturing effects over those achieved via sequential or simultaneous fracturing. Furthermore, the number and magnitude of microseismic events are directly proportional to the stratal movement and compression induced by multistage propagation of fracturing fracture networks.

Microseismic events induced by multistage propagation of 3D multiple hydraulic fractures and perforation cluster spaces and fracturing scenarios that impact the deformation and compression among fractures in porous rock matrices are well predicted and analyzed.

Simultaneous hydrofracturing of multiple perforation clusters in vertical wells has been applied in the stimulation of hydrocarbon resources reservoirs. This technology is significantly impeded due to the challenges in its application to the multilayered reservoirs that comprise multiple interlayers. One of the challenges is the accurate understanding and characterization of propagation and deflection of the multiple hydraulic fractures between reservoirs and embedded interlayers.

Numerical models of the tight multilayered reservoirs containing multiple interlayers were established to study hydrofracturing of multiple perforation clusters and its influencing factors on unstable propagation and deflection of hydraulic fractures. Brittle and plastic multilayered reservoirs fully considering the influences of different in situ stress ratio and physical attributes for reservoir and interlayer strata on propagations of hydraulic fractures were investigated. The combined finite element–discrete element method and mesh refinement strategy were adopted to guarantee the accuracy of stress solutions and reliability of fracture path in computation.

Results show that the shear stress fields between adjacent multiple hydraulic fractures are superposed to cause fractures deflection. Stress shadows induce the shielding effects of hydraulic fractures and inhibit fractures growth to emerge unstable propagation behaviors, and a main single fracture and several minor fractures develop. As the in situ stress ratio increases, hydraulic fractures more easily deflect toward the direction of maximum in situ stress, and stress shadow and mutual interaction effects between them are intensified. Compared to brittle reservoir, plastic-enhanced reservoir may limit fracture growth and cannot form long fracture length; nevertheless, plastic properties of reservoir are prone to induce more microseismic events with larger magnitude.

The obtained fracturing behaviors and mechanisms based on engineering-scale multilayered reservoir may provide effective schemes for controlling and estimating the unstable propagation of multiple hydraulic fractures.

The main purpose of this paper is to present a comprehensive upscale theory of the thermo-mechanical coupling particle simulation for three-dimensional (3D) large-scale non-isothermal problems, so that a small 3D length-scale particle model can exactly reproduce the same mechanical and thermal results with that of a large 3D length-scale one.

The objective is achieved by following the scaling methodology proposed by Feng and Owen (2014).

After four basic physical quantities and their similarity-ratios are chosen, the derived quantities and its similarity-ratios can be derived from its dimensions. As the proposed comprehensive 3D upscale theory contains five similarity criteria, it reveals the intrinsic relationship between the particle-simulation solution obtained from a small 3D length-scale (e.g. a laboratory length-scale) model and that obtained from a large 3D length-scale (e.g. a geological length-scale) one. The scale invariance of the 3D interaction law in the thermo-mechanical coupled particle model is examined. The proposed 3D upscale theory is tested through two typical examples. Finally, a practical application example of 3D transient heat flow in a solid with constant heat flux is given to illustrate the performance of the proposed 3D upscale theory in the thermo-mechanical coupling particle simulation of 3D large-scale non-isothermal problems. Both the benchmark tests and application example are provided to demonstrate the correctness and usefulness of the proposed 3D upscale theory for simulating 3D non-isothermal problems using the particle simulation method.

The paper provides some important theoretical guidance to modeling 3D large-scale non-isothermal problems at both the engineering length-scale (i.e. the meter-scale) and the geological length-scale (i.e. the kilometer-scale) using the particle simulation method directly.

The aim of this paper is to present a discussion on prognosis and mitigation of major landslide zones in an attempt to minimize the impact of such disasters in future. A case study on the sequence of sliding events of Varunavat Parvat, Uttarkashi (India), response of masses and administration and causative factors of sliding events has been presented in detail for prognosis and mitigation of large slide zones.

The prognosis and mitigation strategy discussed is based on the monitoring of mass wasting zones through field investigations and satellite image analysis (of pre‐ and post‐landslide period images) and experiential learning and interaction with village elders in landslide hazard‐prone Himalayan terrain.

The paper finds that Himalayan habitations such as Uttarkashi (which is situated in an area of fragile rocks, complex tectonics, seismic activity and cloud burst‐prone unstable hill slopes with colluvium and old slide zones) should have minimum anthropogenic activity in the form of slope cutting for road or building construction.

The paper reflects the author's individual understanding of causative factors and indications of landslides in Varunavat Parvat area in Uttarkashi township of Uttarakhand (India).

The paper calls for amalgamation of experience‐based local knowledge of villagers of landslide‐prone areas and modern scientific and technical know‐how and above all the coordinated efforts of community and authorities for prognosis and mitigation of large‐scale landslides in the inhabited areas. It has been further emphasized that sensitization and awareness programs and strict implementation of land‐use regulations are vital components of effective mitigation strategy.

Ultra low permeability rocks such as shales exhibit complex fracture networks which must be discretely characterized in our reservoir models to evaluate stimulation designs and completion strategies properly. The pressure (Darcy’s law) and composition driven (Fick’s law) flow mechanisms when combined result in composition, pressure and saturationdependent slippage factor. The approach used in this study is to utilize pressure-dependent transmissibility multipliers to incorporate apparent gas-permeability changes resulting from multi-mechanism flows in commercial simulators. This work further expounds on the effectiveness of the theory by presenting a descriptive analysis between two commercially utilized numerical simulators. The applicability of dynamic slippage as an effective flow mechanism governing gas flow mechanisms within the computational environment of two different simulators is attempted in this analysis. Results indicate that slippage-governed flow in modelling shale reservoirs should not be ignored.

Today’s in-demand skills may not be needed tomorrow. As companies are adopting a new group of technologies, they are in huge need of information technology (IT) professionals who can fill various IT positions with a mixture of technical and problem-solving skills. This study aims to adopt a sematic analysis approach to explore how the US Information Systems (IS) programs meet the challenges of emerging IT topics.

This study considers the application of a hybrid semantic analysis approach to the analysis of IS higher education programs in the USA. It proposes a semantic analysis framework and a semantic analysis algorithm to analyze and evaluate the context of the IS programs. To be more specific, the study uses digital transformation as a case study to examine the readiness of the IS programs in the USA to meet the challenges of digital transformation. First, this study developed a knowledge pool of 15 principles and 98 keywords from an extensive literature review on digital transformation. Second, this study collects 4,093 IS courses from 315 IS programs in the USA and 493,216 scientific publication records from the Web of Science Core Collection.

Using the knowledge pool and two collected data sets, the semantic analysis algorithm was implemented to compute a semantic similarity score (DxScore) between an IS course’s context and digital transformation. To present the credibility of the research results of this paper, the state ranking using the similarity scores and the state employment ranking were compared. The research results can be used by IS educators in the future in the process of updating the IS curricula. Regarding IT professionals in the industry, the results can provide insights into the training of their current/future employees.

This study explores the status of the IS programs in the USA by proposing a semantic analysis framework, using digital transformation as a case study to illustrate the application of the proposed semantic analysis framework, and developing a knowledge pool, a corpus and a course information collection.

The purpose of this paper is to examine how experiencing moderate earthquakes influences risk perception and preparedness.

An online survey was conducted on a nationally representative sample of Korean adults after the moderate earthquake in Pohang in 2017. Statistical analyses were conducted to identify the determinants of willingness to pay (WTP) for seismic retrofitting and earthquake insurance.

The results show that risk perception, housing ownership, earthquake experience and income level significantly influenced WTP for seismic retrofitting and earthquake insurance. The results also indicate that a greater number of damage-free earthquake experiences reduced the WTP that could be explained by normalcy bias. Finally, people who believed that the Pohang earthquake might be an example of induced seismicity (i.e. triggered by the geothermal power plant) tended to have a lower WTP for seismic retrofitting.

This study offers valuable findings on public attitudes about enhancing earthquake preparedness policies in moderate earthquake zones, regions that few studies have examined despite their high vulnerability due to a lack of preparedness.

Accra, the capital of Ghana is far away from major earthquake zones of the world, but has a history of destructive earthquakes. However, its seismic risk does not attract the requisite attention. The purpose of this paper is to give an overview of Accra's seismic risk, discuss challenges faced and risk‐reduction initiatives, and then to propose specific strategies that are necessary to reduce this risk.

The approach taken is to: give an overview of Accra's profile and seismicity; discuss disaster management structures in place and the challenges faced; discuss seismic risk‐reduction programs; discuss the risk‐reduction strategies of two cities in other developing countries, with the view of identifying specific strategies that would be helpful to Accra; and conclude with specific risk‐reduction action measures that are important for Accra.

A number of specific recommendations to reduce Accra's seismic risk are made at the end of the paper. Among these, the need to set up a national organization with the sole mandate of championing seismic risk reduction is identified as a critical step needed. Without this, and others, the paper contends that Accra would not experience any significant reduction of its seismic risk.

The paper presents a viewpoint of important action steps that need to be taken to reduce Accra's seismic risk. The points raised in the paper are considered as important first steps necessary for any form of sustainable disaster risk reduction. The paper would thus be of interest to any person or organization interested in helping reduce Accra's seismic risk.

This is the first paper to put Accra's seismic risk in a global context, and then propose action steps that are necessary to help reduce this risk.