Method of controlling scale in oil recovery operations

Claim 1

A method of producing heavy viscous petroleum crude oil from a subterranean formation which comprises the steps of: a burning a sulfur containing fuel with a substantially stoichiometric amount of air in a pressurized combustion chamber to achieve substantially complete combustion of the fuel, in the presence of sufficient injected water to maintain temperatures of from about 590° C. to about 2200° C., to form a combustion gas; injecting water and ammonia into the combustion gas to produce a thermal vapor stream; warming downstream piping and a well bore combmunicating with a subterranean deposit of heavy viscous petroleum crude oil, venting a portion of the vapor stream from the well to maintain gas velocity in the well to lift condensed liquids from the well, for a time sufficient to warm the piping, well bore and the subterranean formation adjacent the well bore; ceasing the venting from the well and reducing the injection of ammonia into the combustion gases and water into the combustion chamber to allow acidic compounds, formed in the pressurized combustion chamber, to be injected into the subterranean formation through the well bore with the vapor stream whereby the acidic compounds in the vapor stream increase the acidity of the connate water in the formation; discontinuing the injection of the thermal vapor stream when the formation and oil is heated; and recovering the petroleum crude oil from the well bore.

Claim 2

A method of producing heavy viscous petroleum crude oil from a subterranean formation which comprises the steps of: a burning a sulfur containing fuel with a substantially stoichiometric amount of air in a pressurized combustion chamber to achieve substantially complete combustion of the fuel, in the presence of sufficient injected water to maintain temperatures of from about 590° C. to about 2200° C., to form a combustion gas; injecting water and ammonia into the combustion gas to produce a thermal vapor stream; warming downstream piping and a well bore combmunicating with a subterranean deposit of heavy viscous petroleum crude oil, venting a portion of the vapor stream from the well to maintain gas velocity in the well to lift condensed liquids from the well, for a time sufficient to warm the piping, well bore and the subterranean formation adjacent the well bore; ceasing the venting from the well and reducing the injection of ammonia into the combustion gases and water into the combustion chamber to allow acidic compounds, formed in the pressurized combustion chamber, to be injected into the subterranean formation through the well bore with the vapor stream whereby the acidic compounds in the vapor stream increase the acidity of the connate water in the formation; discontinuing the injection of the thermal vapor stream when the formation and oil is heated; and recovering the petroleum crude oil from the well bore.