Method and Device for Cementing a Well or a Pipe

Method for cementing a well or a pipe, for example a casing (C), having a portion to be treated, in particular to be repaired and/or plugged, according to which:

• g) a tubular mandrel (1) is introduced into the well or pipe, around which mandrel there is mounted an inflatable membrane (2) which is also tubular and is made of a flexible and elastic material which can expand radially under the effect of an internal pressure, and this assembly is positioned opposite the portion to be cemented;
• h) a pressurised fluid (L1) is introduced into the membrane (2) and the latter is inflated in such a way that, on the one hand, its end zones dilate radially and considerably, forming annular beads which are applied firmly against the wall of the well or pipe, on either side of the portion to be cemented, and that, on the other hand, its zone—referred to as the median zone—located between its end zones also dilates radially, but with a lesser amplitude, so that an annular space (Σ) is formed between this median zone and the portion of wall to be cemented;
• i) while the membrane (2) is kept inflated, a liquid but curable cement (L2) is injected into this annular space;
• j) the cement is left to set so that it forms a solid sleeve (GC) which internally coats said wall portion of the well or pipe;
• k) the tubular membrane (2) is deflated;
• l) the assembly consisting of the mandrel (1) and the deflated membrane (2) is withdrawn from the well or pipe.