Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
132 words
A method of cementing in the low temperature zone of an environment having a low temperature zone below about 80° F, which comprises: 1. providing a slurry comprising portland cement and the calcium sulfate hemihydrate form of gypsum in a weight ratio of from 3:1 to 1:3 and, based on the total weight of said portland cement and gypsum, a. from about 5 to about 25 percent urea, b. from about 0.1 to about 2 percent of at least one retarder selected from the group consisting of i. a water soluble salt of lignosulfonic acid, ii. a low molecular weight hydroxypolycarboxylic acid, iii. a sodium, potassium, or lithium salt of a low molecular weight hydroxypolycarboxylic acid, and iv. an alkaline hexametaphosphate, and c. from about 25 to about 50 percent water; 2.
Claim 2
Independent Claim
132 words
A method of cementing in the low temperature zone of an environment having a low temperature zone below about 80° F, which comprises: 1. providing a slurry comprising portland cement and the calcium sulfate hemihydrate form of gypsum in a weight ratio of from 3:1 to 1:3 and, based on the total weight of said portland cement and gypsum, a. from about 5 to about 25 percent urea, b. from about 0.1 to about 2 percent of at least one retarder selected from the group consisting of i. a water soluble salt of lignosulfonic acid, ii. a low molecular weight hydroxypolycarboxylic acid, iii. a sodium, potassium, or lithium salt of a low molecular weight hydroxypolycarboxylic acid, and iv. an alkaline hexametaphosphate, and c. from about 25 to about 50 percent water; 2.
Claim 3
Dependent Claim
9 words
transporting said slurry to said low temperture zone; and
Claim 4
Dependent Claim
9 words
transporting said slurry to said low temperture zone; and
Claim 5
Dependent Claim
45 words
permitting the slurry to set up in said low temperature zone. 2. The method of claim 1, including providing in the slurry, from about 0.5 to about 6 percent calcium chloride, calculated as the dihydrate, based on the weight of the portland cement and gypsum.
Claim 6
Dependent Claim
29 words
The method of claim 1, wherein from about 35 to about 45 percent water is provided in the slurry, based on the weight of the portland cement and gypsum.
Claim 7
Dependent Claim
19 words
The method of claim 1 wherein the environment is a borehole penetrating the low temperature zone to be cemented.
Claim 8
Dependent Claim
42 words
The method of claim 1 wherein the environment also has a high temperature zone of at least about 80° F and the slurry is transported through said high temperature zone before it is permitted to set up in said low temperature zone.
Claim 9
Dependent Claim
63 words
The method of claim 5 wherein the environment is a borehole extending through a permafrost zone sufficiently deeply so that the borehole has a high temperature zone as defined in claim 36, comprising pumping the slurry through the permafrost zone into the high temperature zone, and then back into the permafrost zone before permitting the slurry to set up in said permafrost zone.
Claim 10
Dependent Claim
29 words
The method of claim 1 wherein from about 5 to about 15 percent urea is provided in the slurry, based on the weight of the portland cement and gypsum.
Claim 11
Dependent Claim
29 words
The method of claim 7 wherein from about 35 to about 45 percent water is provided in the slurry, based on the weight of the portland cement and gypsum.
Claim 12
Dependent Claim
19 words
The method of claim 8 wherein the environment is a borehole penetrating the low temperature zone to be cemented.
Claim 13
Dependent Claim
42 words
The method of claim 8 wherein the environment also has a high temperature zone of at least about 80° F and the slurry is transported through said high temperature zone before it is permitted to set up in said low temperature zone.
Claim 14
Dependent Claim
63 words
The method of claim 10 wherein the environment is a borehole extending through a permafrost zone sufficiently deeply so that the borehole has a high temperature zone as defined in claim 41, comprising pumping the slurry through the permafrost zone into the high temperature zone, and then back into the permafrost zone before permitting the slurry to set up in said permafrost zone.
Claim 15
Dependent Claim
63 words
The method of claim 1, including providing in the slurry, from about 0.1 to about 5 percent of a dispersant, based on the weight of the portland cement and gypsum, said dispersant comprising a condensation product of mononaphthalenesulfonic acid and formaldehyde, one or more alkali metal or ammonium salt derivatives thereof, or mixtures of said condensation product and any of its recited derivatives.
Claim 16
Dependent Claim
33 words
The method of claim 12, including providing in the slurry, from about 0.5 to about 6 percent calcium chloride, calculated as the dihydrate, based on the weight of the portland cement and gypsum.
Claim 17
Dependent Claim
96 words
The method of claim 13 wherein the portland cement is a Class G portland cement and the weight ratio of portland cement to gypsum is 1:1 to 1:3, and wherein the following components are provided in the slurry in the amount specified, based on the total weight of the portland cement and gypsum: urea about 5 to about 15 percent; calcium chloride, expressed as the dihydrate, about 1 to about 3 percent; said dispersant, about 0.3 to about 0.7 percent; water, about 35 to about 45 percent; and calcium lignosulfonate, about 0.4 to about 1 percent.
Claim 18
Dependent Claim
19 words
The method of claim 14 wherein the environment is a borehole penetrating the low temperature zone to be cemented.
Claim 19
Dependent Claim
42 words
The method of claim 14 wherein the environment also has a high temperature zone of at least about 80° F and the slurry is transported through said high temperature zone before it is permitted to set up in said low temperature zone.
Claim 20
Dependent Claim
63 words
The method of claim 16 wherein the environment is a borehole extending through a permafrost zone sufficiently deeply so that the borehole has a high temperature zone as defined in claim 47, comprising pumping the slurry through the permafrost zone into the high temperature zone, and then back into the permafrost zone before permitting the slurry to set up in said permafrost zone.