Abstract: The present invention relates to a riser pipe element comprising a main tube (5), connection means (2) at both ends, at least one auxiliary pipe length (4) arranged substantially parallel to the tube. The auxiliary pipe length is secured at both ends to the connection means of the main tube so that the longitudinal mechanical stresses to which the connection means are subjected are distributed in the tube and in the pipe.

Abstract: A method is provided for improving the coefficient of transmission to geological formations of the energy generated by the firing of a seismic source lowered inside a well or borehole and a device for implementing same. A zone of the wall containing the seismic source is defined by confinement so as to prevent the propagation along the well, outside the confined zone, of the energy generated therein by the seismic source, when fired. The confinement is achieved by closing off the wall on each side of the seismic source. Two expandable members are used disposed in the wall on each side of the source and each comprising for example an elastomer sheath, an annular piston whose movement causes expansion of the sheath and hydraulic means for moving the piston.