Search results

Multi-well hydrofracturing is a key technology in engineering, and the evaluation, control and optimization of the fracturing network determine the recovery rate of unconventional oil and gas production. In engineering terms, altering well spacing and perforation initiation sequences changes fracture propagation behavior. Fracture propagation can result in fracture-to-fracture and well-to-well interactions. This may be attributed to the interference between fractures caused by squeezing of the reservoir strata. Meanwhile, the stratal movement caused by the propagation of the fractures may lead to either the secondary fracturing of wells with primary fractures or perforation to begin fracturing. Besides, the stratal compression and squeeze of multi-well hydrofracturing will cause earthquakes; the fracture size is different owing to the different fracturing scenarios, and the occurrence of induced microseismic events is still unknown; microseismic events also affect fracture orientation and deflection. If the mechanism of the above mechanical behavior cannot be clarified, optimizing the fracture network and reduce the induced microseismic disaster becomes difficult.

In this study, combined finite element-discrete element models were used to simulate the multi-well hydrofracturing. Numerical cases compared the fracture network, dynamic stratal movement and microseismic events at 50, 75 and 100 m well spacings, respectively, and varying initiation sequence of multiple horizontal wells.

From the results, fracture propagation in multi-well hydrofracturing may simulate the propagation and deflection of adjacent fractures and induce fracture-to-fracture and well-to-well interactions. As the well spacing increases, the effect of fracturing-induced stratal movement and squeezing deformation decrease. In alternate fracturing, starting from a well located in the middle can effectively reduce the influence of stratal movement on fracturing, and the fracturing scenario with cross-perforation can minimize the influence of stratal movement. The stratal movement between multiple wells is positively correlated to microseismic events, which behaviors can be effectively weakened by reducing the strata movement.

The fracture network, thermal-hydro-mechanical coupling, fracturing-induced stratal movement and microseismic events were analyzed. This study analyzed the intersection and propagation behavior of fractures in multi-well hydrofracturing, which can be used to evaluate and study the mechanism of hydrofracturing fracture network propagation in multiple horizontal wells and conduct fracture optimization research to form an optimized hydrofracturing scheme by reasonably arranging the spacing between wells and initiation sequences of perforation clusters.

Multi-well hydrofracturing is an important technology to create new fractures and expand existing fractures to increase reservoir permeability. The propagation morphology of the fracture network is affected by the disturbance between the fractures initiation sequences and spacings between adjacent wells. However, it remains unclear how well spacing and initiation sequences lead to fracture propagation, deflection and connection.

In this study, the thermal-hydro-mechanical coupling effect in the hydrofracturing process was considered, to establish a finite element-discrete element model of multistage hydrofracturing in a horizontal well. Using typical cases, the unstable propagation of hydraulic fractures in multiple horizontal wells was investigated under varying well spacing and initiation sequences. Combined with the shear stress shadow caused by in situ stress disturbed by fracture tip propagation, the quantitative indexes of fracture propagation such as length, volume, displacement vector, deflection and unstable propagation behavior of the hydrofracturing fracture network were analyzed.

The results show that the shear stress disturbance caused by multiple hydraulic fractures is a significant factor in multi-well hydrofracturing. Reducing the spacing between multiple wells increases the stress shadow area and aggravates the mutual disturbance and deflection between the fractures. The quantitative analysis results show that a decrease of well spacing reduces the total length of hydraulic fractures but increases the total volume of the fracture; compared with sequential and simultaneous fracturing, alternate fracturing can effectively reduce stress shadow area, alleviate fracture disturbance and generate larger fracture propagation length and volume.

The numerical models and results of the unstable propagation and stress evolution of the hydraulic fracture network under thermal-hydro-mechanical coupling obtained in this study can provide useful guidance for the evaluation and design of rock mass fracture networks in deep unconventional oil and gas reservoirs.

The unstable dynamic propagation of multistage hydrofracturing fractures leads to uneven development of the fracture network and research on the mechanism controlling this phenomenon indicates that the stress shadow effects around the fractures are the main mechanism causing this behaviour. Further studies and simulations of the stress shadow effects are necessary to understand the controlling mechanism and evaluate the fracturing effect.

In the process of stress-dependent unstable dynamic propagation of fractures, there are both continuous stress fields and discontinuous fractures; therefore, in order to study the stress-dependent unstable dynamic propagation of multistage fracture networks, a series of continuum-discontinuum numerical methods and models are reviewed, including the well-developed extended finite element method, displacement discontinuity method, boundary element method and finite element-discrete element method.

The superposition of the surrounding stress field during fracture propagation causes different degrees of stress shadow effects between fractures and the main controlling factors of stress shadow effects are fracture initiation sequence, perforation cluster spacing and well spacing. The perforation cluster spacing varies with the initiation sequence, resulting in different stress shadow effects between fractures; for example, the smaller the perforation cluster spacing and well spacing are, the stronger the stress shadow effects are and the more seriously the fracture propagation inhibition arises. Moreover, as the spacing of perforation clusters and well spacing increases, the stress shadow effects decrease and the fracture propagation follows an almost straight pattern. In addition, the computed results of the dynamic distribution of stress-dependent unstable dynamic propagation of fractures under different stress fields are summarised.

A state-of-art review of stress shadow effects and continuum-discontinuum methods for stress-dependent unstable dynamic propagation of multiple hydraulic fractures are well summarized and analysed. This paper can provide a reference for those engaged in the research of unstable dynamic propagation of multiple hydraulic structures and have a comprehensive grasp of the research in this field.

This paper seeks to introduce a model of the initiation process in negotiations, and to describe a study of the effects of culture and personality on propensity to initiate and assertiveness in negotiations.

Using a survey research approach and hierarchical regression analyses, initiation propensity and assertiveness were regressed against two country cultures diverse with respect to perceived appropriateness of initiation (Brazil and the USA) and four measures of personality (self‐efficacy, locus of control, risk propensity, Machiavellianism).

Regression analyses found three personality factors (risk propensity, self‐efficacy, Machiavellianism) to be most significantly associated with initiation propensity/assertiveness, along with an interaction effect involving country culture and risk propensity.

Future studies might benefit from a broader, more diverse subject pool (beyond the two countries studied). This would allow for separate analyses of cultural dimensions, rather than treating culture as a composite measure. In addition, future research might include measures of actual initiation behavior.

Initiation is a manageable process. Self‐efficacy, for example, can be improved by observing others skilled in the initiation process, and through practicing initiation under more favorable conditions. Furthermore, an individual can follow a graduated approach to gain initiation confidence, beginning with simply engaging (without asking) and progressing to asking and optimizing.

This paper offers a model for understanding the dynamics of the initiation process in negotiations, which generally has been overlooked by negotiation researchers. The study examines two sets of factors that can influence initiation behavior that have not been investigated in total – culture and personality.

The purpose of this study is to investigate the unstable propagation of parallel hydraulic fractures induced by interferences of adjacent perforation clusters and thermal diffusion. Fracture propagation in the process of multistage fracturing of a rock mass is deflected owing to various factors. Hydrofracturing of rock masses in deep tight reservoirs involves thermal diffusion, fluid flow and deformation of rock between the rock matrix and fluid in pores and fractures.

To study the unstable propagation behaviours of three-dimensional (3D) parallel hydraulic fractures induced by the interferences of adjacent perforation clusters and thermal diffusion, a 3D engineering-scale numerical model is established under different fracturing scenarios (sequential, simultaneous and alternate fracturing) and different perforation cluster spacings while considering the thermal-hydro-mechanical coupling effect. Stress disturbance region caused by fracture propagation in a deep tight rock mass is superimposed and overlaid with multiple fractures, resulting in a stress shadow effect and fracture deflection.

The results show that the size of the stress shadow areas and the interaction between fractures increase with decreasing multiple perforation cluster spacing in horizontal wells. Alternate fracturing can produce more fracture areas and improve the fracturing effect compared with those of sequential and simultaneous fracturing. The larger the temperature gradient between the fracturing fluid and rock matrix, the stronger the thermal diffusion effect, and the effect of thermal diffusion on the fracture propagation is significant.

This study focuses on the behaviours of the unstable dynamic propagation of 3D parallel hydraulic fractures induced by the interferences of adjacent perforation clusters and thermal diffusion. Further, the temperature field affects the fracture deflection requires could be investigated from the mechanisms; this paper is to study the unstable propagation of fractures in single horizontal well, which can provide a basis for fracture propagation and stress field disturbance in multiple horizontal wells.

To enhance one's understanding of the evolution of knowledge management (KM), this study seeks to develop a research model to examine the impact of individual (knowledge self‐efficacy, openness in communication, reciprocal benefits), organizational (top management support, organizational rewards, and sharing culture), and information technology contexts (KM system infrastructure and KM system quality) on the KM evolution along three stages (KM initiation, implementation, and institutionalization).

Survey data from 241 managers (in charge of KM practices in their companies) in large Taiwanese firms were collected and used to test the research model using the structural equation modeling (SEM) approach.

The results reveal that the attributes for individual‐organizational‐technological contexts have different impacts on three stages of KM evolution. In particular, knowledge self‐efficacy, top management support, and KM system quality have positive effects on all three KM evolution stages.

Future research should include structured interviews and case studies of managers dealing with ongoing or recently completed KM planning projects to help understand the practical usefulness of the research model.

Creating an organizational climate characterized by top management support and knowledge‐sharing culture is likely to assist both management and employees in socializing and interacting with one another, thus driving KM effectiveness. Managers should strive to enable employees to propose ideas for new opportunities and foster a positive social interaction culture for implementing KM initiatives.

Theoretically, this study aims to provide a research model that is capable of understanding the antecedents of the stage‐based KM evolution. From a managerial perspective, the findings of this study provide valuable guidelines to policy‐makers and practitioners in implementing KM and accelerating KM evolution.

The purpose of this paper is to find the key influence factors of executive compensation within China ports and listed shipping companies and provide some reasonable suggestions. Eventually, help to perfect the executive compensation evaluation mechanism against the background of new area.

Grey correlation analysis is an important part of grey system theory. Professor Liu Sifeng further studies the relationship between two sequences absolute increment on the basis of Deng’s degree and put forward the “Grey absolute correlation degree,” which is widely used in practice. In the study, on the basis of the area of the line between sequences size, it measures the correlation degrees of firm performance, executive stock holding, continuous growth capacity and other relevant factors of executive payment in China ports and listed shipping companies.

The paper concludes that the main factors influence CEO salary in China ports and listed shipping companies are return on equity and growth rate of fixed assets. However, the authors consider the frequent occurrence of executives’ corruption in China listed state-owned enterprise under the environment of financial and economic crisis, the authors argue that the significant influence of net assets attributed to shareholders cannot be ignored. In addition, cash flow in operating activities and executive stock holding both have relatively important effect on executive compensation.

This paper still has some limitations. First, it merely takes into account the financial indicators and ignores the influence of non-financial indicators to the performance evaluation of listed companies, such as: innovation ability, human capital and goodwill. Second, it has not considered the power consumption and other types of “invisible income” in the executive compensation structure, neither the influence of investing and financing activities on corporate performance. Consequently, these are likely to cause a certain deviation to the results of the study.

The outcome obtained in this paper can be provided for China ports and listed shipping companies to establish a reasonable executive compensation evaluation and incentive mechanism under the background of depressed shipping market.

This paper intends to use correlation analysis between firm performance, executive stock holding, sustainability and executive compensation in the new area of time, tries to make a greater contribution to the major component of salary policy and then make some suggestions on incentive supervising and restraining mechanisms for the ports and listed shipping firms in China.

Although scholars have done many studies about the association analysis of executive compensation and firm performance, they neglect the economic environment of industry. Meanwhile, considering the non-financial indicators and incomplete information, this paper studies the grey correlation analysis of executive compensation and influence factors in China ports and listed shipping firms under the background of the Chinese flagging shipping industry.

There are several connections between education and disinformation, including the association between years of schooling and vulnerability to unfounded hypothesizing. The purpose of this paper is to inquire into a competing explanation: political leaders might be exploring powerful teaching and learning strategies to disseminate agendas based on baseless assumptions, exploiting human’s tendency to generate robust theories even with incomplete or incorrect information.

The authors analyzed ten videos published online by a highly partisan YouTube channel. The footage contained informal encounters between former Brazilian President Jair Bolsonaro and supporters in front of his official residence. The team sought to answer two research questions: Do Mr Bolsonaro’s discursive moves include activators that lead the audience to understand that they are theorizing and reaching conclusions “on their own?” Does Mr Bolsonaro’s audience follow those clues and mention politically motivated hoaxes and conspiracy theories in their comments? This paper draws on perspectives from the field of educational research to investigate the mechanisms used by the president to shape public opinion.

The authors found evidence of the employment of elements akin to classroom discourse in the dialogues led by Mr Bolsonaro. Specifically, different types of rhetorical questions are present to a substantial extent in the data subset analyzed for this paper.

This work offers an alternative perspective to analyzing disinformation. By drawing from established literature from education research, this paper departs from facile explanations that take for granted the lack of intelligence of the audience. Conversely, it argues that popular, if not powerful, teaching and learning strategies might play an undesired role by shaping individuals’ cognitive processes to create robust, internally consistent theories about the world using flawed assumptions and incorrect “building blocks.”

This paper proposes introducing how to consider the break which cyclically happens and has nothing to do with resource availabilities in modeling of a construction process through an activity‐based simulation.

In consideration of the variable break‐frequency and break‐duration for different activities, concepts of time‐cycle and time‐window are discussed. Then an algorithm to determine the execution of the activities facing the cyclical break is proposed, in which pre‐emption or non‐pre‐emption cases and overtime are taken into account together. This algorithm is incorporated into an activity‐based simulation so that the improved construction simulation is able to consider the cyclical break and model the construction process more reasonably. Computational analyses are presented to address the effectiveness of the improved activity‐based simulation.

The computational analyses demonstrate that the improved activity‐based simulation can consider the cyclical break in modeling a construction process, which cannot be achieved by the traditional simulation tools, especially when non‐pre‐emptive activities are concerned. It is also shown that the overtime use for the non‐pre‐emptive activities can lead to reduction of the project duration when the cyclical break is considered.

The proposed simulation‐based methodology is an alternative means to deal with the cyclical break that is destined for some activities and irrelevant to resource availabilities in modeling of a construction process.

A measuring system for automatic process parameter acquisition in garment sewing operations has been presented. The measuring equipment is based upon the usage of a very powerful portable notebook IBM compatible personal computer, equipped with an AD converter, measuring instruments and adequate software packages for data storing and analysis. Characteristics of measuring instruments and sensors have also been given, together with measuring process description, all connected with two independent video‐camera systems, working in two planes, used for working operation analysis at workplaces in garment sewing operations.