A complete series of 3D walkaway borehole profiles have been collected for the Ekofisk Field that are expected to image most of the crestal area of the field. This area has gas present in the overburden which obscures the seismic imaging using conventional surface seismic data. Good compressional images are obtained by undershooting the gas zones and taking advantage of the small Fresnel zones using the 3D walkaway technique. Considerable compressional to shear wave conversion was observed at the reservoir level in these profiles. Shear waves may be particularly suitable for imaging because they are less affected by gas than the compressional waves. Several 3D walkaway borehole profile surveys have been used to derive a 3D up-going shear image. This paper describes the results of this shear wave work from one of these surveys.
The structure and properties of sputter NiFe thin film deposited on both thermal oxide and thin tantalum nitride have been studied. The magnetic anisotropy field HK increases to 8.2 Oe when the NiFe film was deposited on a thin tantalum nitride underlayer. Anisotropic stress was found on the sample film with tantalum nitride underlayer. Results of X-ray diffraction show that a thin tantalum nitride underlayer appears to promote a preferred crystalline orientation formation of the NiFe film. The induced magnetic anisotropy is attributed to the formation of the preferred crystalline orientation and the induced anisotropic magnetoelastic energy which is associated with the anisotropic stress of the sample film.
A b s t r u c t -The manner in which magnetization reversal process of coupled NiFeCo films are affected by various surface topography conditions of integrated circuit (IC) underlayers was examined. The experimental results demonstrated that the topography of underlayers play a significant role in affecting the magnetization reversal characteristics of the coupled films. A hysteresis loop with lower coercivity and homogeneous switching field distribution can be obtained for the coupled films deposited on underlayer with a smooth surface topography. When the coupled films were deposited on underlayers having severe surface topography, a hysteresis loop with higher coercivity and inhomogeneous switching field distribution was obtained. Such behavior may be attributed to induced inhomogeneous coupling in the coupled films due to the severe topography.
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