Invert emulsion drilling mud
AssigneesJ.K.F. Investments Ltd., Hour Holdings Ltd.
InventorsJames K. Fleming, Harold C. Fleming
Life of this patent
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Abstract
A water-in-oil invert emulsion drilling mud is prepared with a nitrogen-containing compound, as a brine solution in the aqueous phase, to prevent the hydration of subterranean formation clays. Suitable nitrogen-containing compounds include alkali metal, alkaline-earth metal and ammonium nitrates and nitrites, and hydrates and complexes thereof. The nitrogen-based invert emulsion mud of the present invention eliminates the use of calcium chloride in the prior art invert emulsion drilling muds, thereby reducing the environmental impact of the drilling operation.
Claims17
A water-in-oil invert emulsion drilling mud comprising an emulsifier, a surfactant, a clay, an alkaline substance and a nitrogen-containing compound selected from the group consisting of hydrated complex alkali metal ammonium nitrates and nitrites and hydrated complex alkaline earth metal ammonium nitrates and nitrites, for reducing or preventing hydration of subterranean formation clays, wherein the concentration of water in the mud is in the range of from about 5 to 50% by volume and the concentration of the nitrogen-containing compound is in the range of from about 5 to 80% by weight of the water.
In a method of drilling a borehole, comprising the steps of providing an initial water-in-oil invert emulsion drilling mud in the borehole, recirculating the drilling mud to the surface, screening rock cuttings from the drilling mud and returning the screened drilling mud to the borehole, and analysing the properties of the drilling mud, the improved step of supplementing the drilling mud with a nitrogen-containing compound for reducing or preventing hydration of subterranean formation clays, where the concentration of water in the mud is in the range of from about 5 to 50% by volume and the concentration of the nitrogen-containing compound is in the range of from about 5 to 80% by weight of the water, wherein the nitrogen-containing compound is selected from the group consisting of hydrated complex alkali metal ammonium nitrates and nitrites and hydrated complex alkaline earth metal ammonium nitrates and nitrites.
A kit for formulating a water-in-oil invert emulsion drilling mud comprising an emulsifier, a surfactant, a clay, an alkaline substance and a nitrogen-containing compound for reducing or preventing hydration of subterranean formation clays, wherein the nitrogen-containing compound is selected from the group consisting of hydrated complex alkali metal ammonium nitrates and nitrites and hydrated complex alkaline earth metal ammonium nitrates and nitrites.
Dependencies are inferred from the claim text.