Inferring Hydraulic Connectivity of Induced Fractures in the Near-wellbore Region Using DAS-recorded Tube Waves Excited by Perforation Shots

We present a novel use of tube waves exited by perforation (or “perf”) shots and recorded on distributed acoustic sensing (DAS) to infer and compare the hydraulic connectivity of induced fractures near the wellbore on a stage-by-stage basis. Evaluating the fracture connectivity near the wellbore is critical since it controls the flow of the hydrocarbons from the formation to the wellbore. Currently, there are no established methods used to assess this property. However, we discuss how tube wave decay rates can be used to infer relative differences in fracture connectivity between stages and, through field observations on DAS, demonstrate the correlation between decay rates and frac effectiveness. Additionally, we consider other potential uses of this data in unconventional wells such as assessing plug integrity and constraining fracture geometry with Krauklis waves. DAS data is commonly acquired during the perf shots but primarily for fiber depth calibration purposes and has not been well studied. Our work illustrates the untapped potential of this data and how it can be easily repurposed to bring new insights about fracture characteristics in the near-wellbore region.

Physical processes behind interactions of microplastic particles with natural ice

Microplastic particles (MPs, <5 mm) are found in marine ice in larger quantities than in seawater, however, the distribution pattern within the ice cores is not consistent. To get insights into the most general physical processes behind interactions of ice and plastic particles in cool natural environments, information from academic and applied research is integrated and verified against available field observations. Non-polar molecules of common-market plastics are hydrophobic, so MPs are weak ice nucleators, are repelled from water and ice, and concentrate within air bubbles and brine channels. A large difference in thermal properties of ice and plastics favours concentration of MPs at the ice surface during freeze/thaw cycles. Under low environmental temperatures, falling in polar regions below the glass / brittle-ductile transition temperatures of the common-use plastics, they become brittle. This might partially explain the absence of floating macroplastics in polar waters. Freshwater freezes at the temperature well below that of its maximum density, so the water column is stably stratified, and MPs eventually concentrate at the ice surface and in air bubbles. In contrast, below growing sea ice, mechanisms of suspension freezing under conditions of (thermal plus haline) convection should permanently entangle MPs into ice. During further sea ice growth and aging, MPs are repelled from water and ice into air bubbles, brine channels, and to the upper/lower boundaries of the ice column. Sea ice permeability, especially while melting periods, can re-distribute sub-millimeter MPs through the brine channels, thus potentially introducing the variability of contamination with time. In accord with field observations, analysis reveals several competing factors that influence the distribution of MPs in sea ice. A thorough sampling of the upper ice surface, prevention of brine leakage while sampling and handling, considering the ice structure while segmenting the ice core – these steps may be advantageous for further understanding the pattern of plastic contamination in natural ice.

A Fatigue Reliability Assessment for Rail Tension Clamps Based on Field Measurement Data

Tension clamps play an important role in maintaining the track gauge by fixing the rails to the sleepers. Damage to the tension clamps was observed on an urban railway. The cause of the fracturing of the tension clamps was identified and reliability analyses on the fatigue failure of the tension clamps were performed. The stress ranges were estimated by measuring the strain at the locations where most of the fractures occurred during train operation. Afterward, a statistical model of the stress ranges was developed using the measured data. The statistical parameters of the stress ranges for the reliability analysis were estimated based on the field measurement data. The reliability indexes were calculated for the inner and outer rails and for the inside and outside track gauges of each rail. The variations of the reliability index for the years in service and the number of cycles were investigated. The results of the reliability analyses showed a consistency with the field observations.

Factors Affecting Citizen Participation in Local Development Planning in Murewa District, Zimbabwe

Local governments are the bedrock for sound public administration because of their role in promoting bottom-up socio-economic development. Although Zimbabwe has made strides in ensuring citizens’ participation in local government processes, local authorities and other stakeholders still rely on the top-down approaches, marginalising the needs of the local citizens. The purpose of this paper is to determine the factors that affect the active participation of citizens in local governance in the Murewa District in Zimbabwe. Based on a multistage sampling approach, involving purposive sampling and stratified random sampling, interviews were conducted with 30 local government officials, while a questionnaire survey was administered to 396 citizens in four wards within the district. Complementary data were collected through focus group discussions and field observations. Thematic analysis was employed on data generated from interviews, focus group discussions and field observations, while the Statistical Package for the Social Sciences (Version 16) was used to analyse quantitative data from the questionnaire survey. The results show that more than 50% of the residents in the district felt that local government leadership side lined them in development planning. Some citizens reported that officials used development planning meetings to further their political agendas. The study recommends enhancement of citizen participation through citizen empowerment programmes such as educational and political leadership training programmes that transform the marginalised communities into autonomous communities that are capable of determining their own destiny.

Estimasi Model Hidrolika Menggunakan HEC-RAS 1-D dan Tren Prediksi Strategi Mitigasi Banjir

Engineering modeling is becoming a trend and important because it can simulate a variety of decision scenarios to be applied in the field. With limited facilities and technology, 1-D modeling in hydraulics for flood mitigation is still a trend today. What are the weaknesses of this model and how is the prediction of future modeling trends? This study analyzes the flood modeling of the Tuntang River with the 1-D model using HEC-RAS to analyze the condition of the existing water level profile and flood mitigation scenarios with normalization. The results of the analysis show that the 1-D model can describe conditions in the field and scenarios clearly. However, the 1-D model has limitations because it cannot carry out simulations that consider aspects of construction costs, time, and budget allocation of stakeholders to determine the priority scale of disaster-affected areas. It requires a vulnerability analysis with field observations, 2-D or 3-D modeling, and the application of value engineering to optimize flood control strategies. With the advancement of technology, this trend is predicted to be something that will be done in the future.

"Why are you single, baby?" Reasons for being single based on a Brazilian research

Single people are often asked about the reasons for non-marriage, in a context where, despite several changes in the field of intimacy, adults are still expected to marry. Based on a thesis study on the subject of singleness in Brazil, in the city of Salvador, Bahia, this text presents the main reasons for singleness, declared by single middle-class adults who live alone in this city. The study used a feminist perspective, with the category gender as the basis for data analysis, in an intersectional way with social class, race, generation, sexuality and territoriality. It used mixed methods with a combination of instruments: questionnaire, focus groups, biographical interviews, and field observations. The findings collaborate to observe gender differences and closeness in reasons for singleness: relational reasons prevailing for women and being single as a choice for men.