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The Integration of real-time high frequency data in well models allows to infer useful information regarding well and field performance. Virtual Metering (VM) algorithms aim at providing real time well rates solving an inverse problem based on flow equation in the wellbore. Although VM methodologies are based on Pressure/Temperature measurements, they rely on availability of calibration measurements. Pressure Transient Analysis (PTA) can provide useful insight for VM calibration. An innovative closed-loop workflow combining VM and PTA has been developed to face unreliable or absent rate measurements. VM requires periodical separator tests for model calibration. PTA played an important role in estimating well production rates, using it as a virtual well test to compensate the lack of field tests. VM rates are used as first guess for the PTA interpretation of build-up where production rates are unreliable. PTA log-log derivative plot is compared with the reference one which was interpreted to calibrate the formation K•H. The loop is iterated correcting VM calibration parameters until the match is acceptable. An implementation of the closed loop rate estimation workflow on an offshore oil asset is presented as an application of the methodology. The asset comprises 15 production wells, most of them with high Gas-Oil Ratio. Virtual Metering has been applied on wells fully equipped with wellhead and bottom-hole sensors. The joint application of PTA with an iterative closed loop philosophy was fundamental to compensate the lack of separator tests and of the sometimes unreliable choke opening data. The accuracy of the production profiles simulated by the VM is confirmed by the comparison with the reference asset fiscal production and by the final pressure history matching obtained with the PTA. The application of the iterative closed-loop workflow plays a fundamental role in the improvement of backallocation, in real time production monitoring and in the implementation of production optimization. Well models based on VM algorithm have been included in production optimization workflow to improve the well line-up and identify production optimization opportunities. Virtual Metering allowed to monitor results of optimization actions by estimating the actual wells production increment. This paper contains a novel approach, consisting in a reliable and robust closed loop virtual metering workflow, which integrates different tools with the common objective of assessing the actual well production rates for maximising the asset performance. The real-time data and model sharing allowed to set-up a collaborative environment optimizing effective problem solving and field production performance.

The possibility of designing and running an AO system working in the visible for observations with a large diameter telescope is still under debate due to the large number of sub-pupils required to properly sample the incoming WaveFront. On the other hand, the situation is much more relaxed in the IR, where r0 is much larger, and several systems are forthcoming or already in operation. Morossi et al. proposed to support IR AO system with on-line multi-aperture selection devices. They showed that the image quality of a ground-based telescope in the visual could be improved by means of pupil segmentation and on-line multi- sub-aperture selection notwithstanding the large D/r0 ratio.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The possibility of improving the image quality of the Italian “Telescopio Nazionale Galileo (TNG)” by means of on-line image selection via a fast shutter is discussed. The different performances obtainable with different shutter speeds, selection rates and sharpness criteria are derived by the analysis of temporal series of simulated short exposure images of atmospheric speckles. The speckles are obtained by drifting large format phase screens of von Karman statistics over the telescope pupil. The phase screens are generated by FFT transforming a white noise of controlled quality and by adding subharmonics to approximate the low frequency pattern. Particular attention is devoted to the identification of the most suitable merit function(s) for on-line image selection and to the comparison of the achievable image quality improvements with those obtainable through off-line selection and co-addition post-processing techniques.

The possibility of improving the image quality of the Italian Telescopio Nazionale Galileo (TNG) by means of real-time on- line image selection by using a fast shutter is studied. The tip-tilt signal is checked against a user defined threshold to trigger on rejection of those images which would significantly degrade the long-exposure point spread function because of jitter broadening. The dependency of the achievable improvements on the rejection threshold, on the shutter opening and closing times, and on the atmosphere conditions (ro) is analyzed. The pros and cons of a ferroelectric liquid crystal shutter are discussed.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Maksutov scheme for the compensation of an aspheric concave mirror by means of a single spherical mirror is described. The residual longitudinal spherical aberration and the corresponding Zernike polynomial coefficient are computed. The optical error budget for the scheme, as obtained from the analytical computations and by means of the CODE V program for design and engineering of optical systems, is presented. The application of such a scheme to the verification of the figuring of the hyperbolic primary mirror (D equals 1.70 m) of the T-170 Telescope to be launched on board of the Russia/Ukraine/Italy/Germany SPECTRUM UV satellite is discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper describes the design and the realization of a multiple-function photoelectric photometer made by Trieste Observatory for Torino Observatory. The system design shows a two-beam, sequential multiband photon counting and analog photoelectric photometer configuration based on a PDP8/E computer for the control and data acquisition and elaboration. The actual realization of the system and the use of it in the one-beam configuration operating now at torino Observatory shows the advantages of such a solution and the easiness in modifying and determining the system functions by software programs rather than by hardware specials.

The two methodologies applied in this study develop the widely accepted concept that the lithosphere is built-up by different-scale blocks, separated by mobile boundaries. The aim of this work is to provide new insights about active deformations and to improve seismic hazard assessment in the Alps and surrounding areas. The Morphostructural Zonation method, MSZ (Alekseevskaya et al., 1977), allows for the identification of the sites capable of the strong events, while the block model of the lithosphere dynamics (Gabrielov et al., 1990) permits to generate a synthetic catalogue of earthquakes to be used for the analysis of some long-term features of seismic energy release in the modeled region. TRANSALP Conference (2003), Trieste