Compositions and methods for plaster-based thermal grout
AssigneeSchlumberger Technology Corporation
InventorsHortencia Torres, Nicolas Droger, Mark Meade, Christopher Parton, Dmitry Kuravskiy
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Abstract
A grout composition includes a grout binder comprising calcium sulfate, the grout binder constituting from about 25.0 weight percent to about 99.0 weight percent of the grout composition, and at least one thermal conductivity additive comprising graphite. A grout formed from the grout composition has a thermal conductivity greater than about 1.0 W/m·K. Related grout slurries formed from the grout composition, grouts, and methods of grouting a wellbore are also disclosed.
Claims15
A grout composition, comprising:
- a grout binder comprising calcium sulfate, the grout binder constituting from about 25.0 weight percent to about 99.0 weight percent of the grout composition;
- at least one thermal conductivity additive comprising graphite;
- and
- at least one retarder comprising borax and ethylenediamine tetra(methylene phosphonic acid), wherein a ratio of borax to ethylenediamine tetra(methylene phosphonic acid) in the at least one retarder is within a range of from about 5.0:1.0 to about 10.0:1.0.
A grout slurry composition, comprising:
- water;
- at least one grout binder comprising at least about 50 weight percent calcium sulfate;
- at least one thermal conductivity additive comprising graphite, wherein the grout slurry composition has a density within a range of from about 1,050 kg/m3 to about 1,450 kg/m3 and a viscosity within a range of from about 10 cP to about 1,000 cP at about 25° C.;
- and
- at least one retarder comprising borax and ethylenediamine tetra(methylene phosphonic acid), wherein the at least one retarder is within a range of from about 0.01 weight percent to about 4.0 weight percent based on the grout slurry composition not including the water.
A method of grouting a shallow geothermal wellbore, the method comprising:
- pumping a grout slurry in a wellbore extending through an earth formation between surfaces of the earth formation defining the wellbore and a thermal transfer pipe, the grout slurry having a density within a range of from about 1,050 kg/m3 to about 1,450 kg/m3 and comprising:
- water;
- at least about 25.0 weight percent calcium sulfate hemihydrate based on the grout slurry composition not including the water;
- and
- at least about 10.0 weight percent graphite based on the grout slurry composition not including the water;
- at least one retarder comprising borax and ethylenediamine tetra(methylene phosphonic acid), wherein a ratio of borax to ethylenediamine tetra(methylene phosphonic acid) in the at least one retarder is within a range of from about 5.0:1.0 to about 10.0:1.0;
- and
- setting the grout slurry to form a grout having a thermal conductivity within a range of from about 1.0 W/m·K to about 10.0 W/m·K.
Dependencies are inferred from the claim text.