Abstract: Methods of compressing sonic data acquired as the result of well logging procedures are disclosed. Samples of each digitized formation wave component are characterized as a vector. Eigenvectors based on the formation wave component vectors are obtained, and selected wave components are correlated to the eigenvectors to obtain scaler correlation factors. The eigenvectors and correlation factors together provide a compressed representation of the selected formation wave component, particularly since only a few eigenvectors and correlation factors are required to provide an excellent reconstruction of the formation wave component.

Abstract: A pressure sensor of the present invention can perform pressure measurements under very severe mechanical and thermal conditions. It comprises a cell carrying a strain-measuring circuit. The cell is placed inside a body and is put into contact with the pressure to be measured. The cell has a hermetically sealed internal chamber inside which pressure is set to a predetermined reference value. The outside surface of the cell is subjected to the pressure to be measured. The cell is constituted by two half-shells joined together according to a join plane. The cell is preferably made of sapphire, with the crystal axis of the sapphire being perpendicular to the join plane so as to obtain isotropic stresses. A strain-gauge circuit is deposited on a plane surface of one of the half-shells, parallel to the join plane. The sensor is particularly suitable for testing oil deposits.