Cellulosic suspensions of alkali formate and method of using the same
A fluidized cellulosic polymer suspension of a cellulosic polymer in an alkali formate containing solution is particularly efficacious in the thickening of brines, particularly high density brines, in the recovery of oil and/or gas from a subterranean formation. The alkali formate containing solution preferably contains potassium formate, cesium formate or a mixture thereof. A fluid loss pill containing the cellulosic polymer suspension may further contain a crosslinking agent and glycol.
1 . A fluid loss pill comprising:
(a.) cellulosic polymer suspended in an alkali formate solution;
(b.) a crosslinking agent;
(c.) a polyol; and
(d.) brine or water.
2 . The fluid loss pill of claim 1 , wherein the true crystallization temperature (TCT), API 13 J, of the alkali formate solution is less than or equal to 18° F.
3 . The fluid loss pill of claim 1 , wherein the alkali formate solution contains between from about 40 to about 75 weight percent of alkali formate.
4 . The fluid loss pill of claim 1 , wherein the cellulosic polymer is anionic or non-ionic.
5 . The fluid loss pill of claim 4 , wherein the cellulosic polymer is carboxymethylhydroxyethyl cellulose or hydroxyethyl cellulose, optionally crosslinked with glycoxal.
6 . The fluid loss pill of claim 1 , wherein the alkali formate is potassium formate, cesium formate, or a mixture thereof.
7 . The fluid loss pill of claim 2 , wherein the TCT is less than or equal to 0° F.
8 . The fluid loss pill of claim 1 , wherein the brine has a density greater than or equal to 10.5 ppg at 70° F.
9 . The fluid loss pill of claim 1 , wherein the crosslinking agent contains a metal ion.
10 . The fluid loss pill of claim 9 , wherein the crosslinking agent contains zirconium or titanium.
11 . The fluid loss pill of claim 9 , wherein the crosslinking agent is a borate ion donator.
12 . The fluid loss pill of claim 1 , wherein the pH of the fluid loss control pill is between from about 3.0 to about 12.0.
13 . A method of thickening a brine during the recovery of oil and/or gas from a subterranean formation which comprises introducing into the formation the fluid loss pill of claim 1 .
14 . A method of reducing fluid loss from a wellbore into a subterranean formation which comprises:
(a.) introducing a crosslinking agent to a polyol, brine or water, and cellulosic polymer suspended in an alkali formate solution; and
(b.) pumping the resulting thickened product of step (a.) into the wellbore.
15 . The method of claim 14 , wherein the cellulosic polymer suspension, polyol, and brine or water are mixed off-site and shipped to the subterranean formation.
16 . The method of claim 14 , wherein the brine has a density greater than or equal to 10.5 ppg at 70° F.
17 . The method of claim 14 , wherein, the pH of the product of step (a.), prior to being pumped into the wellbore, is between from about 3.0 to about 12.0.
18 . The method of claim 14 , wherein the crosslinking agent contains zirconium, titanium or boron.
19 . The method of claim 14 , wherein the cellulosic polymer is carboxymethylhydroxyethyl cellulose or hydroxyethyl cellulose, optionally crosslinked with glycoxal.
20 . The method of claim 14 , wherein the alkali formate is potassium formate, cesium formate, or a mixture thereof.