Two-level uncertainty assessment in stochastic seismic inversion based on the gradual deformation method

Geostatistical seismic inversion can combine seismic data, well data, and spatial continuity of the property of interest to obtain high-resolution reservoir models and evaluate uncertainties. Some workflows estimate global geostatistical parameters, such as correlation length, and keep them fixed in all simulations and inversions. This can introduce biases due to the sparsity of available well data and underestimate the uncertainty of inversion. A better approach is to incorporate the uncertainty in these global parameters. Lateral correlation length is one of the most difficult parameters to estimate. We have developed a seismic inversion method based on local gradual deformation method, which incorporates the uncertainty of lateral correlation length and provides a two-level uncertainty evaluation. We first estimate a uniform prior distribution of lateral correlation length from well data and additional geologic expert knowledge. After using fast Fourier transform (FFT) moving average simulations and local gradual deformation optimization, we obtain multiple realizations from which we could extract the lateral correlation lengths and calculate their posterior distribution. The FFT moving average method generates reservoir models by a convolution between a filter operator and a random noise field. The filter operator does not change during inversion, and the correlation structure of the random noise field could be changed by the local gradual deformation method to match the seismic data. A synthetic model test shows that the correlation lengths and the global probability distribution of the inverted results tend to the true geostatistical characteristics. The posterior distribution of the lateral correlation length narrows after inversion. Compared with conventional geostatistical seismic inversion techniques, uncertainties in the results increase because we incorporate the uncertainty in the global parameters. A real case also demonstrated that by modifying the random noise field locally, thin layers in a thick formation are well restored, even if they are not interpreted in advance.

THE INFLUENCE OF SUPERPARAMAGNETIC Fe3O4 NANOPARTICLES ON SPECTRAL AND LUMINESCENT PROPERTIES OF MESOSTRUCTURED SiO2/P123/Rh6G/Fe3O4 FILMS FORMED IN STATIONARY MAGNETIC FIELDS

The effect of superparamagnetic Fe3O4 nanoparticles (NPs) on the spectral luminescence properties of homogeneous optically transparent mesostructured silica films of SiO2/P123/Rh6G/Fe3O4, containing {P123 (Rh6G)} micelles consisting of Pluronic 123 with encapsulated Rh6G, and formed in stationary magnetic fields (MF) with an induction of less than 500 mT, was investigated. It was shown that, unlike SiO2/P123/Rh6G, the spectral and luminescent properties of SiO2/P123/Rh6G/Fe3O4 films depend on the MF used during their formation, and a gradual decrease in the band intensities in Rh6G spectra and quenching of luminescence with increasing of MF induction was observed. It is associated with a decrease in the monomer fraction and an increase in the fraction of non-luminescent Rh6G H-aggregates in micelles due to the interaction intensifying in the MF (formation of Fe3+ -O bonds) of superparamagnetic NPs with micelles {P123 (Rh6G)}, oriented in the MF, which leads to a gradual deformation of micelles and accumulation in them of H-aggregate. The dependences of the changes in the absorption bands intensity and fluorescence of the monomeric form of Rh6G in the spectra of the films on the changes in the magnetic induction of the MF are described by an exponential function, and the ratio of the fluorescence intensities of the SiO2/P123/Rh6G films to the fluorescence intensities of the SiO2/P123/Rh6G/Fe3O4 films linearly depends on the induction of MF, which they are able to "remember", which is manifested in the values of fluorescence intensities.

Stability of beta-titanium T-loop springs preactivated by gradual curvature

ABSTRACT Objective: Evaluate changes in the force system of T-Loop Springs (TLS) preactivated by curvature, due to stress relaxation. Methods: Ninety TLSs measuring 6 x 10 mm, produced out with 0.017 x 0.025-in TMA® wire and preactived by gradual curvature, were randomly distributed into nine groups according to time point of evaluation. Group 1 was tested immediately after spring preactivation and stress relief, by trial activation. The other eight groups were tested after 24, 48 and 72 hours, 1, 2, 4, 8 and 12 weeks, respectively. Using a moment transducer coupled to a digital extensometer indicator adapted to a universal testing machine, the amount of horizontal force, moment and moment-to-force ratios were recorded at every 0.5 mm of deactivation from 5 mm of the initial activation, in an interbracket distance of 23 mm. Results: The horizontal forces decreased gradually among the groups (p< 0.001) and the moments showed a significant and slow decrease over time among the groups (p< 0.001). All groups produced similar M/F ratios (p= 0.532), with no influence of time. Conclusions: The TLSs preactivated by curvature suffered a gradual deformation over time, which affected the force system, specifically the moments, which affected the horizontal forces produced.