Spacer fluids for well cementing operations
OwnerMatteo Loizzo, Edgar Volpertinventors
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Abstract
A spacing fluid or “spacer”, of the type comprising a fluid and particles, notably particles of loading agent, as well as possibly normal additives, such as a viscosity-increasing polymer, for separating a cement slurry from borehole fluids during a well cementing operation, characterised in that the spacing fluid has a density close that of the drilling fluid or mud and a viscosity close to that of water, by virtue of the adaptation of the size of the particles to a value less than 5 microns, particularly around 2 to 3 microns or around 0.2 to 0.3 microns, such as by the use of magnesium oxide or rutile.
Claims12
1 A spacer fluid for use in well cementing operations for separating a cement slurry from other fluids present in a well, comprising:
- a mixture of a liquid component and a solid component comprising a particulate loading agent having a particle size of less than 5 microns, the mixture having a density close to that of the drilling fluid or mud and a viscosity close to that of water.
2 A spacer fluid as claimed in claim 1, wherein the particle size of the loading agent is around 2-3 microns.
3 A spacer fluid as claimed in claim 2, wherein the loading agent comprises magnesium oxide particles.
4 A spacer fluid as claimed in claim 1, wherein the particle size of the loading agent is around 0.2-0.3 microns.
5 A spacer fluid as claimed in claim 4 wherein the loading agent comprises titanium oxide.
6 A spacer fluid as claimed in claim 1, further comprising a polymer gel as a viscosity increasing additive.
7 A spacer fluid as claimed in claim 1, further comprising a clay as a viscosity increasing additive.
8 A spacer fluid as claimed in claim 6, wherein the polymer gel is selected from the group consisting of welan gum, gelan gum, modified guar gum, and scleroglucane.
9 A spacer fluid as claimed in claim 6, wherein the polymer gel is present in a quantity sufficient to obtain stable suspensions having an appreciable absence of sedimentation for at least two hours.
10 A spacer fluid as claimed in claim 3, further comprising up to 0.3%, by weight of welan gum polymer as a viscosity increasing additive.
11 A spacer fluid as claimed in claim 10, comprising about 0.075% by weight of welan gum polymer.
12 A spacer fluid as claimed in claim 5, further comprising up to 0.2% by weight of welan gum polymer as a viscosity increasing agent.