Visualizing Wellbore Instability and Fracture Direction by Application of Principal Stress Trajectory Analysis

This study furthers our understanding of the causes of wellbore failure by thoroughly analyzing key properties (e.g., in-situ stress regime, formation and pore pressures, and rock properties) associated with wellbore instability. Regardless of whether a wellbore is planned to be drilled underbalanced or overbalanced, local formation pressures, and even operational practices (e.g., shutting off the pumps while drilling) can quickly render a wellbore locally unstable. Near-borehole stress mechanics associated with stress cages (overbalanced holes) and with fracture cages (underbalanced holes) are further studied, including an analysis showing the impact tangential and radial stress magnitudes have on principal stress trajectory patterns. With a deeper understanding of stress cages and fracture cages, wellbore failure can, consequently, be quantified and visually evaluated to a greater extent. Stress trajectory analytical solutions can be rapidly applied for a wide range of in-situ stress and pressure conditions, which enable us to better predict, and therefore mitigate, wellbore instabilities associate with tensional and shear failure, and also estimate more assuredly unknown parameters that drive wellbore instability. The wellbore stress model in this study accounts for different in-situ stress regimes, borehole net fluid pressures, and poroelastic effects. Drilling software equipped with these tools may help reduce the occurrence of failure, saving drillers from countless hours of non-productive time and other associated costs

Sustainability action plan booklet

Learn about our commitment to maintaining a high quality of life while pursuing a progressive approach to environmental issues. Also, read about our guiding principles with information provided in the new Sustainability Action Plan booklet

Green Initiatives

City practices incorporating energy conservation methods

An Attestation Architecture for Blockchain Networks

If blockchain networks are to become the building blocks of the infrastructure for the future digital economy, then several challenges related to the resiliency and survivability of blockchain networks need to be addressed. The survivability of a blockchain network is influenced by the diversity of its nodes. Trustworthy device-level attestations permits nodes in a blockchain network to provide truthful evidence regarding their current configuration, operational state, keying material and other system attributes. In the current work we review the recent developments towards a standard attestation architecture and evidence conveyance protocols. We explore the applicability and benefits of a standard attestation architecture to blockchain networks. Finally, we discuss a number of open challenges related to node attestations that has arisen due to changing model of blockchain network deployments, such as the use virtualization and containerization technologies for nodes in cloud infrastructures.Comment: 33 pages, 10 figure

The pro sequence of lactase-phlorizin hydrolase is required for the enzyme to reach the plasma membrane An intramolecular chaperone?

AbstractVarious cDNAs coding for part or all of human pre-pro lactase-phlorizin hydrolase (pre-proLPH) were transfected into COS cells and the subcellular location of the lactase-related proteins assessed. Only the complete proLPH reached the plasma membrane. LPH without the pro sequence, and a construct containing the pro sequence and the lactase domain of mature LPH, accumulated intracellularly; the pro sequence with no mature domain was secreted. We conclude that the pro sequence is important for LPH to be transported to the cell surface

Sustainability booklet

An online booklet highlighting the responsible efforts being made by the City of Henderson to foster a sustainable community

Ecotypic differences in the phenology of the tundra species Eriophorum vaginatum reflect sites of origin

Eriophorum vaginatum is a tussock-forming sedge that contributes significantly to the structure and primary productivity of moist acidic tussock tundra. Locally adapted populations (ecotypes) have been identified across the geographical distribution of E. vaginatum; however, little is known about how their growth and phenology differ over the course of a growing season. The growing season is short in the Arctic and therefore exerts a strong selection pressure on tundra species. This raises the hypothesis that the phenology of arctic species may be poorly adapted if the timing and length of the growing season change. Mature E. vaginatum tussocks from across a latitudinal gradient (65–70°N) were transplanted into a common garden at a central location (Toolik Lake, 68°38′N, 149°36′W) where half were warmed using open-top chambers. Over two growing seasons (2015 and 2016), leaf length was measured weekly to track growth rates, timing of senescence, and biomass accumulation. Growth rates were similar across ecotypes and between years and were not affected by warming. However, southern populations accumulated significantly more biomass, largely because they started to senesce later. In 2016, peak biomass and senescence of most populations occurred later than in 2015, probably induced by colder weather at the beginning of the growing season in 2016, which caused a delayed start to growth. The finish was delayed as well. Differences in phenology between populations were largely retained between years, suggesting that the amount of time that these ecotypes grow has been selected by the length of the growing seasons at their respective home sites. As potential growing seasons lengthen, E. vaginatum may be unable to respond appropriately as a result of genetic control and may have reduced fitness in the rapidly warming Arctic tundra

The potential of the fractions of lifeworld for inclusive qualitative inquiry in the third space

In this paper we introduce the lifeworld fractions (Ashworth 2003) as a methodological framework for inclusive research with autistic people 'with profound learning disabilities'. We first define the fractions and then evaluate their potential for enabling research within the ‘third space’ of inclusive research (Seale, Nind, Tilley, & Chapman 2015). Fundamental to the third space is the inclusion of the social and support circles of people with profound learning disabilities within research. Using the example of a recent study we illustrate how the fractions are a useful enabler of this. We conclude by suggesting that a key value of the fractions is in how they take the research collective beyond the elements of experience that most obviously confront them to consider its full breadth and effects. We argue too that the fractions support the management of the collation and analysis of the copious amounts of data that are generated through qualitative research. We conclude by offering a new and critical dimension to the fractions through presenting them as a means through which those involved in the third space – autistic people, their social and support circles, and researchers - can come to more emic understandings of lived experience

Differential responses of ecotypes to climate in a ubiquitous arctic sedge: implications for future ecosystem C cycling

The response of vegetation to climate change has implications for the carbon cycle and global climate. It is frequently assumed that a species responds uniformly across its range to climate change. However, ecotypes—locally adapted populations within a species—display differences in traits, which may affect their gross primary productivity (GPP) and response to climate change. To determine if ecotypes are important for understanding the response of ecosystem productivity to climate we measured and modeled growing season GPP in reciprocally transplanted and experimentally warmed ecotypes of the abundant arctic sedge Eriophorum vaginatum. Transplanted northern ecotypes displayed home site advantage in GPP that was associated with differences in leaf area index. Southern ecotypes exhibited a greater response in GPP when transplanted. The results demonstrate that ecotypic differentiation can impact the morphology and function of vegetation with implications for carbon cycling. Moreover they suggest that ecotypic control of GPP may limit the response of ecosystem productivity to climate change. This investigation shows that ecotypes play a substantial role in determining GPP and its response to climate. These results have implications for understanding annual to decadal carbon cycling where ecotypes could influence ecosystem function and vegetation feedbacks to climate change