Wellbore fluid comprising a base fluid and a particulate bridging agent
AssigneeBP Exploration Operating Company Limited
InventorsSimon Neil Duncum, Christopher Alan Sawdon
Life of this patent
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Abstract
A wellbore fluid comprising a base fluid and a particulate bridging agent comprised of a sparingly water-soluble material selected from the group consisting of melamine (2,4,5-triamino-1,3,5-triazine), lithium carbonate, lithium phosphate (Li3PO4), and magnesium sulfite.
Claims21
A method of forming a filter cake on the walls of a water injection wellbore or a production wellbore that penetrates a porous and permeable rock formation and of subsequently removing the filter cake from the walls of the wellbore comprising the steps of:
- (a) placing a wellbore fluid in the wellbore wherein the wellbore comprises a base fluid and a particular bridging agent comprised of a sparingly water-soluble material selected from the group consisting of lithium carbonate, lithium phosphate, and magnesium sulfite;
- (b) permitting the particulate bridging agent to deposit from the wellbore fluid onto and/or onto the walls of the wellbore thereby forming the filter cake, whereby fluid loss to the formation through the filter cake is reduced;
- and
- (c) removing the filter cake from the walls of the wellbore by injecting water that is undersaturated with respect of the bridging agent from the injection wellbore into the formation or producing fluid comprising hydrocarbon and co-produced water from the formation into the production wellbore wherein the co-produced water is undersaturated with respect to the bridging agent.
A method of forming a filter cake on the walls of a wellbore that penetrates a porous and permeable rock formation and of subsequently removing the filter cake from the walls of the wellbore comprising the steps of:
- (a) placing a wellbore fluid in the wellbore wherein the wellbore comprises a base fluid and a particular bridging agent comprised of a sparingly water-soluble material selected from the group consisting of lithium carbonate, lithium phosphate, and magnesium sulfite;
- (b) permitting the particulate bridging agent to deposit from the wellbore fluid onto the walls of the wellbore thereby forming the filter cake, whereby fluid loss to the formation through the filter cake is reduced;
- and
- (c) removing the filter cake from the walls of the wellbore by (i) placing a clean-up fluid downhole wherein the clean-up fluid is undersaturated with respect to the bridging agent or is an aqueous solution of an acid or a precursor of a weak acid;
- and (ii)leaving the cleanup fluid to soak across the interval of the wellbore where it is desired to remove the filter cake for a sufficient period of time to either dissolve the bridging agent or solubilise the bridging agent to the extent that the particles are sufficiently reduced in size to permit their removal from the filter cake.
Dependencies are inferred from the claim text.