84 research outputs found
Seismic forward modelling of rock and uid properties in carbonates: Reducing uncertainty in data-poor environments
No full textThe main challenge in frontier and near-field exploration is the limited availability of data to interpret the subsurface. In the absence (or prior to drilling) of an appraisal well, possibly only seismic data and prior geology knowledge are at hand. In such data-poor environments, techniques are required that are able to quickly test large amounts of geology scenarios in a high dimensional (many unknown parameters) model space. Markov Chain Monte Carlo optimization techniques have previously shown to be capable of realizing reasonable solutions for large modelling problems, but are less effcient when the problem has very limited prior knowledge available. Optimization techniques as Particle Swarm Optimization and Cuckoo Search may however be able to de-risk the seismic amplitudes with the use of limited prior knowledge, since they may evaluate large sets of potential rock and uid property scenarios in parallel. To validate the applicability of these techniques, they are tested on their capability of solving mineralogy and porosity in a case-study on the Shuaiba Formation, with only limited prior data available. Cuckoo Search in particular has proven to be suitable to achieve reasonable mineralogy and porosity scenarios fitting a seismic section of the Shuaiba Formation. Particle Swarm Optimization has proven to be a robust technique as well, but due to its slightly less exploratory behavior, it has a greater risk of not finding the optimal solution. On the contrary however, if time is limited and effciency is more important than detail, Particle Swarm Optimization may be the preferred tool to use. Both techniques have provided an indication towards a carbonate mineralogy and porosity values only vary in the order of a few percent with respect to prior research. In overall, the model created has shown to be easily applicable by geologists and geophysicists as it requires only limited prior knowledge of the subsurface. The tool may therefore be of great value to the oil and gas business, since it may help decide whether it is worth drilling an appraisal well based on the probabilities of different scenarios, potentially yielding a great economic advantageCivil Engineering and GeosciencesGeoscience and EngineeringApplied Geophysic
Psychische Widerstandsfähigkeit korreliert mit dem Outcome nach anatomischer Schulterprothese
No full textERRATUM: Repetitive recombinant human bone morphogenetic protein 2 injections improve the callus microarchitecture and mechanical stiffness in a sheep model of distraction osteogenesis
No full textDue to a technical error, Dr. Marc-Frederic Pastor was omitted from the author list of this article. The correct author details appear above.<br /
Using reflected seismic waves to estimate rheological properties of the fluid-mud layer for port applications
No full textCurrent Port of Rotterdam procedure is to define the nautical depth based on the density of a fluid-mud layer, that settles at the bottom of the port. Rheological parameters could be an improved indicator for nautical depth and decrease the frequency and cost of dredging. I investigate the use of reflected seismic waves to derive in situ rheological parameters. I model a simplified port profile to investigate the effects of o_set on the types of seismic reflections acquired. Four models of how the density of the fluid-mud layer varies with depth are proposed. I undertake simple laboratory experiments to measure the effects of consolidation time, density and frequency has on the seismic velocities of the fluid-mud layer. From these laboratory experiments I calculate the shear modulus, bulk modulus, Young's modulus and Poisson's ratio for the fluid-mud layer of varying densities. Reflected seismic-wave velocities prove to be promising in deriving in situ rheological parameters, elastic constants and, potentially, viscosity.Applied Geophysic
Method of Molerus and Wellman to Compute the Pressure Drop of Slurry Transport in Horizontal Pipes
No full textIn the literaturey many methods for the calculation of pipeline hydraulic transport of solids have been published. Their degree of exactness and applicability is variabie and therefore it is hard to the designer to make a convincible decision regarding their practical use. A new concept for the computation of slurry hydraulic transport in horizontal pipes proposed by O. Molerus and P. Wellmann based on numerous measurement data seems to provide a practicle method to predict the head loss in slurry pipeline transport. In this report the new method is introduced and a number of new experimental results to verify the new concept. Furthermore some suggestions are presented te impreve the new methed.Hydraulic EngineeringCivil Engineering and Geoscience
Combining Geophysics and Basin Modeling to Develop a Thermal Model in an Offshore Block, Mexican Gulf of Mexico: Constraining Source Rock Maturity Through OAT Sensitivity Analyses of Key Inputs
No full textThe recent discovery of the Zama field in offshore Sureste Basin in the southern Gulf of Mexico has piqued interest in the Mexican petroleum industry regarding the hydrocarbon potential within the region. In this study, a deposition-only thermal model was developed in an area of interest (AOI) in this region. Using structural input obtained from seismic interpretation conducted in Petrel©, the model was constructed and simulated in PetroMod© to acquire initial estimates of the maturity of the Tithonian J100 source rock in the AOI in terms of the maturity parameters Vitrinite Reflectance (%Ro) and Transformation Ratio (TR). A one-at-a-time (OAT) sensitivity analysis approach was also undertaken to assess the impact of uncertainties in some inputs in isolation on the output maturity in order to identify key uncertain input parameters. Based on the modeling results, at the C-1 well location of interest within the AOI, the source rock was simulated to be within the wet gas generation window based on simulated %Ro values in the present, having emerged into oil window between 41 - 27 Ma (late Eocene-Oligocene) and into the wet gas window between 6 - 0.5Ma (late Miocene-Pleistocene). Across the wider AOI, present-day %Ro values indicate the predominant presence of late oil to wet gas generation windows, with most of the source rock across the AOI having emerged into the oil generation window between 23 Ma and 11.6 Ma (early to middle Miocene). The highest uncertainties in simulated %Ro values were associated with uncertainties in the Bajocian (J60) autochtonous salt sequence thickness distribution and with the maturity models used for model simulation. At the C-1 well location, TR values of 95% to near 100% in the present indicate that most of the kerogen (source rock organic matter) has already been converted into hydrocarbons, with kerogen conversion initiated between 55 - 48 Ma at the location. Across the wider AOI, average present-day TR values in the range of 81 - 97% were simulated. The highest uncertainties in simulated TR values were also associated with uncertainties in the Bajocian (J60) autochtonous salt sequence thickness distribution, and with the source rock maturation kinetics input used for model simulation. The timing of maturation of the J100 source rock at the C-1 well location - assumed to have been constrained by the OAT sensitivity analyses results for simplicity - in relation to the timing of other petroleum system elements and processes indicated by literature, suggests that hydrocarbon accumulations charged from the Tithonian source rock in the reservoir intervals in the well vicinity are possible i.e. presence of hydrocarbon accumulations cannot be ruled out based only on maturation timing considerations.Applied Geophysics | IDEA Leagu
Erythropoietin for the Repair of Cerebral Injury in Very Preterm Infants (EpoRepair).
No full textBACKGROUND
Preterm infants suffering from intraventricular hemorrhage (IVH) are at increased risk for neurodevelopmental impairment. Observational data suggest that recombinant human erythropoietin (rEPO) improves long-term cognitive outcome in infants with IVH. Recent studies revealed a beneficial effect of early high-dose rEPO on white matter development in preterm infants determined by magnetic resonance imaging (MRI).
OBJECTIVES
To summarize the current evidence and to delineate the study protocol of the EpoRepair trial (Erythropoietin for the Repair of Cerebral Injury in Very Preterm Infants).
METHODS
The study involves a review of the literature and the design of a double-blind, placebo-controlled, multicenter trial of repetitive high-dose rEPO administration, enrolling 120 very preterm infants with moderate-to-severe IVH diagnosed by cranial ultrasound in the first days of life, qualitative and quantitative MRI at term-equivalent age and long-term neurodevelopmental follow-up until 5 years of age.
RESULTS AND CONCLUSIONS
The hypothesis generated by observational data that rEPO may improve long-term cognitive outcomes of preterm infants suffering from IVH are to be confirmed or refuted by the randomized controlled trial, EpoRepair
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