Spatial Orientation And Distribution Of Reservoir Fractures From Scattered Seismic Energy

Shortened title: Fracture characterization from coda wavesWe present the details of a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations we have made from 3D finite difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fractures impart a ringing coda type signature to any seismic energy which is transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: 1) the difference in angle between the orientation of the fractures and the acquisition direction, 2) the fracture spacing, 3) the wavelength of the illuminating seismic energy, and 4) the compliance, or stiffness, of the fractures. This coda energy is the most coherent when the acquisition direction is parallel to the strike of the fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. Our method uses surface seismic reflection traces to derive a transfer function which quantifies the change in an apparent source wavelet before and after propagating through a fractured interval. The transfer function for an interval with no or low amounts of scattering will be more spike-like and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. When a 3D survey is acquired with a full range of azimuths, the variation in the derived transfer functions allows us to identify subsurface areas with high fracturing and determine the strike of those fractures. We calibrated the method with model data and then applied it to the Emilio field with a fractured reservoir giving results which agree with known field measurements and previously published fracture orientations derived from PS anisotropy.Eni S.p.A. (Firm)United States. Dept. of Energy (Grant number DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources Laborator

Fracture Properties From Seismic Scattering

Fractures scatter seismic energy and this energy can be analyzed to provide information about fracture direction and density. Laboratory and numerical (finite difference) models of fractures show that scattered energy varies with the seismic acquisition direction relative to the orientation of parallel fracture sets. Data acquired normal to fracture strike displays forward and backscattered energy that is canceled in the stacking process, while data acquired parallel to the fracture strike contains forward scattered and guided waves that are enhanced by stacking. The Scattering Index method estimates the fracture orientation by comparing wavelet changes in the data from azimuthal stacks. Fracture density or spacing can be estimated by spectral methods that include f-k analysis of backscattered energy or analysis of spectral notches as functions of azimuth. Application of these methods to data from a fractured carbonate field results in fracture orientation and density estimates that are consistent with borehole measurements.United States. Dept. of Energy (Award Number DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources LaboratoryEni S.p.A. (Firm

Fracture properties from seismic scattering

The seismic trace is a complex aggregate of reflected and scattered signals from subsurface formation interfaces and heterogeneities. Although many varieties of random noise may also be present in the trace, we know from reacquiring the same seismic survey that seismic data are highly repeatable, indicating that significant information about the subsurface is contained in the trace but not yet used by our standard analysis methods. Seismic scattering is a type of signal contained in the data that is generally not utilized

Prevalence of osteoporosis and vertebral fractures in acromegalic patients

Growth Hormone (GH) and Insulin-like Growth Factor (IGF-1) stimulate proliferation, differentiation and extracellular matrix production in osteoblastic cells. GH and IGF-1 also stimulate recruitment and bone resorption activity in osteoclastic cells. A chronic systemic GH and IGF-1 excess produces an increased bone turn over in acromegalic patients (pts). Osteoporosis, joint alterations and bone deformities have a great clinical relevance in acromegalic pts and favour mortality and morbility. In the present study we evaluate the still unclear GH/IGF-1 activity on bone, Bone Mineral Density (BMD) and risk of osteoporotic Vertebral Fractures (VF), in relation to gender and gonadal status in acromegalic pts

A Preliminary Study on Photic Driving in the Electroencephalogram of Children with Autism across a Wide Cognitive and Behavioral Range

Abstract: Intermittent photic stimulation (IPS) is a useful technique in electroencephalography (EEG) to investigate the neurophysiological anomalies of brain activity. Although not an active task, IPS has also been explored in ASD; it is thought to capture local potential oscillators at specific frequencies and perhaps tap into rhythmic activity in a way that general resting-state recordings cannot. Previous studies suggest that individuals with ASD showed photic driving reactivity predominantly at lower frequencies of stimulation. In our study we used IPS to measure rhythmic oscillatory activity in a sample of 81 ASD children. We found a significant correlation linking ASD children with photic driving activation only at low frequencies ( band) and increased severity of “restricted behavior”. This suggests that ASD children with higher severity of restricted behaviors could have a hypersynchronous power and an impaired resonance synchronization at middle-ranged frequencies (). Furthermore, we found some evidence of hemispherical oscillatory asymmetry linked particularly to behavioral impairments. This result is in line with the EEG pattern model indicating a “U-shaped profile” of electrophysiological power alterations with excess power in lowand high-frequency bands and a reduction of power in the middle-ranged frequencies. IPS technique in electroencephalography is confirmed to reveal EEG biomarkers in autistic children, with a focus on spectral power, coherence, and hemisphere asymmetries

STABILIZABILITY AND EXISTENCE OF SYSTEM REPRESENTATIONS FOR DISCRETE-TIME TIME-VARYING SYSTEMS

Discrete, vertically aligned fracture systems impart one or more notches in the spectral ratios of stacked reflected seismic traces. This apparent attenuation is due to the azimuth dependant scattering introduced by the fractures. The most prominent notch is located at the frequency where the P wavelength is about twice the fracture spacing. The frequency location of the notches can be used to determine the fracture spacings. Azimuth stacks with an orientation parallel to the fractures tend not show these spectral notches – allowing for another way to detect the fracture orientation. An analysis of the vertical component of the 3D, ocean bottom cable seismic survey data from the Emilio field, offshore Italy, shows a prominent set of fractures with a spacing of about 30 to 40 meters with orientations that agree with previous studies.Eni S.p.A. (Firm)United States. Dept. of Energy (Grant number DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources Laborator

Evolution of Pediatric Migraine Patients Admitted at an Emergency Department after a 10-Year Follow-Up

Background: Despite its high prevalence, the clinical course of pediatric migraine has not been fully understood, and previous studies present conflicting results. We present here the findings of a 10-year follow-up study involving children with severe migraine pain admitted to our emergency department. Furthermore, all studies were carried out on selected outpatient clinical case studies. Our aim was to evaluate a population of migraine children admitted to an emergency department because of increased severity or frequency of pain or even because of very anxious parents concerning their child’s headache in order to describe their long-term outcomes, whether it differed from that of outpatient populations and to identify possible predictors of prognosis. Methods: We recruited 80 subjects with migraine headaches (mean age 8 years with a range of 4–14 years, 50% females), attending the baseline examination of a population admitted for a headache to the Emergency Department in the first half year of 2012. Of the 80 subjects, 48 (60%) were eligible for follow-up in 2022. We included in our study only patients diagnosed with migraine, according to the diagnostic criteria of the International Classification of Headache Disorders. All were contacted by telephone, and a semi-structured questionnaire was provided to them by email. The association between several possible prognostic factors (gender, familiar neurologic disorders, prenatal and perinatal disorders, social activities, sleep disorders, etc.) and the long-term persistence of migraine headaches were explored using logistic regression analysis. Results: Of 48 subjects with migraine headaches at baseline, 31 (65%) had persistent migraine, and 17 (35%) experienced remission. The preliminary results showed that the presence of neurologic disorders in parents (p p < 0.01—odds ratio 13.18 (2.25–252.74) significantly predicted the 10-year persistence of migraine headaches, while the other considered predictors were found not to influence prognosis. Conclusions: To our knowledge, this was the first study conducted on a selected pediatric population upon admission to the emergency room. Our study suggests that a population of pediatric migraine selected for admission to the emergency department also shows a favorable long-term prognosis, like the studies conducted in the outpatient sample. Familial neurological comorbidity and sleep disorders were unfavorable factors for predicting good outcomes