Abstract: The invention is a device for sampling fluids under pressure from a well which comprises a chamber for retaining the fluid within a sample chamber (01). The chambers includes a first piston which allows or prevents fluid inflow into the lower part of the chamber. The first piston is displaced by means comprising an elastic element (20) disposed in a chamber filled with oil and connected to the piston by a rod (04). Sampled fluid transfer means allows control of the descent of a second piston (02) from the upper part to the lower part of the chamber so that the fluid remains at constant pressure in chamber during the transfer.

Abstract: The present invention relates to a method of oligomerizing olefins M selectively to oligomers Mn, involving a catalytic system comprising at least one organometallic complex with a metal of groups 4 to 10 of the periodic table of molecular volume Vmo, and a micro- or mesoporous solid whose average micropore diameter ? is greater than or equal to ?min defined as a function of the molecular volume (Vmo+nVmM), where n is the number of monomeric olefins strung together upon obtaining the metallacycle intermediate and VmM the molecular volume of the monomeric olefin.

Abstract: The present invention relates to a method of oligomerizing olefins M selectively to oligomers Mn, involving a catalytic system comprising at least one organometallic complex with a metal of groups 4 to 10 of the periodic table of molecular volume Vmo, and a micro- or mesoporous solid whose average micropore diameter ? is greater than or equal to ?min defined as a function of the molecular volume (Vmo+nVmM), where n is the number of monomeric olefins strung together upon obtaining the metallacycle intermediate and VmM the molecular volume of the monomeric olefin.