Diagenesis & Reservoir Quality of the Middle Bakken Formation

The largest continuous oil accumulation ever assessed by the USGS, the Bakken Formation in the Williston Basin, USA, is a tight oil resource with low recovery factors. Increasing the recovery factors from tight hydrocarbon formation has significant economic implications. In this study we show that the effects of diagenesis have significantly affected the reservoir quality of the middle Bakken Formation. Diagenetic processes in the middle Bakken are complex and vary across several scales. Early carbonate cementation exerts the primary control on porosity loss in the middle Bakken. Detailed petrographic examination by electron microscopy reveals multiple textural phases of calcite and dolomite, each of which contributes to changes in the reservoir quality. Cementation by calcite and dolomite has resulted in the low porosity and low permeability in the middle Bakken. Depositional facies have been defined within the middle Bakken. Cementation by carbonate minerals exert a key control on reservoir quality at scales below that of a facies. Porosity in the middle Bakken varies from ~2-10%. Low pressure nitrogen gas sorption experiments show this is composed of pores which are small; predominantly mesoporous in size. Mercury intrusion experiments show pores in the middle Bakken typically have pore throats with radii <100 nm and low pressure nitrogen gas sorption analysis shows pore bodies are <135 nm in size. A significant component of porosity forms as intragranular pores, predominantly in quartz, calcite and dolomite. Previous studies have struggled to unravel the timing and history of porosity-occluding carbonate cement due to its exceptionally fine-grained nature. We have taken a novel approach, using both sequential acid dissolution and in-situ Secondary Ion Mass Spectrometry (SIMS), to determine the carbon and oxygen isotope composition of individual carbonate phases. Coupled with grain-scale compositional analysis by SEM-WDS we show that diagenetic dolomite formed at 5-64°C by replacement of early calcite cement in low temperature, near surface ocean conditions at temperatures of 8-51°C. The results of this PhD show that multi-stage carbonate diagenesis has destroyed, preserved and created porosity in the middle member of the Bakken Formation

An investigation into the adoption of CDIO in distance learning

The Conceive, Design, Implement and Operate Initiative (CDIO) uses integrated learning to develop deep learning of the disciplinary knowledge base whilst simultaneously developing personal, interpersonal, product, process and system building skills. This is achieved through active and experiential learning methods that expose students to experiences engineers will encounter in their profession. These are incorporated not only in the design-build-test experiences that form a crucial part of a CDIO programme but also in discipline focused studies. Active and experiential learning methods are, of course, more difficult to incorporate into distance education. This paper investigates these difficulties and the implications in providing a programme that best achieves the goals of the CDIO approach through contemporary distance education methods. First, the key issues of adopting the CDIO approach in conventional oncampus courses are considered with reference to the development of the CDIO engineering programmes at the University of Liverpool. The different models of distance based delivery of engineering programmes provided by the Open University in the UK, and Deakin University and the University of Southern Queensland in Australia are then presented and issues that may present obstacles to the future adoption of the CDIO approach in these programmes are discussed. The effectiveness and suitability of various solutions to foreseen difficulties in delivering CDIO programmes through distance education are then considered. These include the further development, increased use and interinstitutional sharing of technology based facilities such as Internet facilitated access to laboratory facilities and computer aided learning (CAL) laboratory simulations, on campus workshops, and the development of a virtual engineering enterprise

THE EFFECT OF PRIOR CYCLING ON LEG STIFFNESS DURING RUNNING IN HIGH PERFORMANCE TRIATHLETES

The purpose of this study was to investigate the influence cycling has on lower limb stiffness during the run leg in triathletes. Seven well trained triathletes completed a triathlon-run (TR; run preceded by a 40 km cycle) and a control-run (CR; run at the same pace as TR, but without a prior cycle). Vertical, hip, knee and ankle stiffness measured during double leg jumping (2.2 Hz) were compared both before and after the cycle leg and between TR and CR conditions. Maximum hip and knee moments and knee joint stiffness were significantly greater immediately following cycling. However, maximum hip moments and hip joint stiffness were lower in CR than TR. This study provided an insight into how joint stiffness is altered following cycling and may help explain the perceived loss of coordination reported frequently by triathletes at the start of the run leg

Relativistic mean-field theories for neutron-star physics based on chiral effective field theory

We describe and implement a procedure for determining the couplings of a Relativistic Mean-Field Theory (RMFT) that is optimized for application to neutron star phenomenology. In the standard RMFT approach, the couplings are constrained by comparing the theory's predictions for symmetric matter at saturation density with measured nuclear properties. The theory is then applied to neutron stars which consist of neutron-rich matter at densities ranging up to several times saturation density, which allows for additional astrophysical constraints. In our approach, rather than using the RMFT to extrapolate from symmetric to neutron-rich matter and from finite-sized nuclei to uniform matter, we fit the RMFT to properties of uniform pure neutron matter obtained from chiral effective field theory. Chiral effective field theory incorporates the experimental data for nuclei in the framework of a controlled expansion for nuclear forces valid at nuclear densities and enables us to account for theoretical uncertainties when fitting the RMFT. We construct four simple RMFTs that span the uncertainties provided by chiral effective field theory for neutron matter, and are consistent with current astrophysical constraints on the equation of state. Our RMFTs can be used to model the properties of neutron-rich matter across the vast range of densities and temperatures encountered in neutron stars and their mergers.Comment: V2: Minor corrections, version published in PRC. 12 pages and 5 figure

An investigation into the adoption of CDIO in distance education

The Conceive, Design, Implement and Operate Initiative (CDIO) uses integrated learning to develop deep learning of the disciplinary knowledge base whilst simultaneously developing personal, interpersonal, product, process and system building skills. This is achieved through active and experiential learning methods that expose students to experiences engineers will encounter in their profession. These are incorporated not only in the design-build-test experiences that form a crucial part of a CDIO programme but also in disciplinefocused studies. Active and experiential learning methods are, of course, more difficult to incorporate into distance education. This paper investigates these difficulties and the implications in providing a programme that best achieves the goals of the CDIO approach through contemporary distance education methods.First, the key issues of adopting the CDIO approach in conventional oncampus courses are considered with reference to the development of the CDIO engineering programmes at the University of Liverpool. The different models of distance based delivery of engineering programmes provided by the Open University in the UK, and Deakin University and the University of Southern Queensland in Australia are then presented and issues that may present obstacles to the future adoption of the CDIO approach in these programmes are discussed.The effectiveness and suitability of various solutions to foreseen difficulties in delivering CDIO programmes through distance education are then considered. These include the further development, increased use and interinstitutional sharing of technology based facilities such as Internet facilitated access to laboratory facilities and computer aided learning (CAL) laboratory simulations, oncampus workshops, and the development of a virtual engineering enterprise.<br /

EVALUATING THE USE OF CAMERA TRAPS TO MONITOR POPULATIONS OF UNGULATE PREY IN THE RUSSIAN FAR EAST

Efforts to recover endangered carnivore populations are often limited by insufficient populations of prey. When recovering prey populations, estimates of population density are invaluable metrics to monitor recovery efforts. In Russia, wildlife managers use the Formozov-Malyushev-Pereleshin (FMP) snow tracking method to estimate densities of ungulate prey of the Amur tiger (Panthera tigris). Yet, increasing variability in snow conditions and other challenges have limited its reliability. Camera traps offer a promising alternative approach since managers already use cameras to monitor tigers. However, the assumptions and study design necessary to implement capture-recapture models for tigers are different from those needed to implement models for unmarked populations of prey. In Chapter 1, I estimated densities of wild boar (Sus scrofa), red deer (Cervus canadensis ssp. xanthopygus), roe deer (Capreolus pygargus), and sika deer (Cervus nippon) using Random Encounter models (REM), Space-To-Event models (STE), and Time-To-Event models (TTE), then compared these with FMP estimates within Sikhote-Alin Biosphere Zapovednik. Estimates from the STE and FMP were the most similar, though there were challenges implementing the STE to data from motion-trigger cameras. All models detected a \u3e90% decline in wild boar density due to African Swine Fever. Simulations indicated that greater survey effort for all camera-based methods would be required to achieve a coefficient of variation of 20% (an objective set for this study area in 2006). This is likely cost-prohibitive for many conservation programs due to the high costs of randomly deploying many cameras. To examine the influence of study design on detections of ungulate prey, in Chapter 2 I compared relative abundance indices (RAIs) of prey using: (1) cameras placed on roads to monitor tigers; (2) cameras placed using systematic random sampling; and (3) “off-road” cameras placed 150 meters away from road cameras. Both road and off-road RAIs were greater than random RAIs, and our attempt to approximate representative sampling with off-road cameras ultimately did not work. These results highlight the importance of random sampling to meet the assumptions of unmarked estimators. Detection data of prey species from cameras placed for tiger monitoring should not be used to estimate true abundance of prey species using these models

Optimizing probe selection for fault localization

We investigate the use of probing technology for the purpose of problem determination and fault localization in networks. We present a framework for addressing this issue and implement algorithms that exploit interactions between probe paths to find a small collection of probes that can be used to locate faults. Small probe sets are desirable in order to minimize the costs imposed by probing, such as additional network load and data management requirements. Our results show that although finding the optimal collection of probes is expensive for large networks, efficient approximation algorithms can be used to find a nearly-optimal set