Behind casing wash and cement

A method of performing a downhole wash procedure in an offshore well including an annulus located between a rock formation and a casing having a region with perforations or other openings, the method comprising:

• passing a washing tool down the casing to the region with perforations or openings, the washing tool having a plurality of nozzles and being connected to a supply of wash fluid;
• displacing debris and fluids in the annulus with wash fluid by delivering the wash fluid through the nozzles whilst rotating the washing tool and translating the washing tool in an axial direction with respect to the casing, such that the wash fluid is forced through the perforations and pulses of pressure are created in the annulus that are sufficient to displace the debris and fluids;
• wherein, whilst delivering the wash fluid, the translational movement of the washing tool is in a downward (distal) direction only;
• and
• wherein the volume flow rate of wash fluid through each nozzle is selected from approximately 28 g.p.m., 29 g.p.m., 30 g.p.m., 31 g.p.m., 32 g.p.m., 33 g.p.m., 34 g.p.m., 35 g.p.m., 36 g.p.m., 37 g.p.m., 38 g.p.m., 39 g.p.m., 40 g.p.m., 41 g.p.m., 42 g.p.m., 43 g.p.m., 44 g.p.m., 45 g.p.m., 46 g.p.m., 47 g.p.m., 48 g.p.m., 49 g.p.m., 50 g.p.m., including from 28 to 50 g.p.m., and from 33 to 45 g.p.m.

A method of performing a downhole wash procedure in an offshore well including an annulus located between a rock formation and a casing having a region with perforations or other openings, the method comprising:

• passing a washing tool down the casing to the region with perforations or openings, the washing tool having a plurality of nozzles and being connected to a supply of wash fluid;
• displacing debris and fluids in the annulus with wash fluid by delivering the wash fluid through the nozzles whilst rotating the washing tool and translating the washing tool in an axial direction with respect to the casing, such that the wash fluid is forced through the perforations and pulses of pressure are created in the annulus that are sufficient to displace the debris and fluids;
• wherein, whilst delivering the wash fluid, the translational movement of the washing tool is in a downward (distal) direction only;
• and
• wherein the pressure drop across each nozzle is selected from approximately 2,000 p.s.i., 2,250 p.s.i., 2,500 p.s.i., 2,750 p.s.i., 3,000 p.s.i., 3,250 p.s.i., 3,500 p.s.i., 3,750 p.s.i., 4,000 p.s.i., from 2,000 to 4,000 p.s.i., and from 2,000 to 3,000 p.s.i.