Produced water steam generation process using produced water boiler with gas turbine

Abstract

A method and system for producing steam for use in heavy hydrocarbon recovery operations. Water, containing impurities, produced from the well is separated from hydrocarbons and other materials, and subsequently directly passed to a produced water boiler with online pigging. The boiler is indirectly heated by means of a hot flue gas, such as a gas turbine exhaust, which produces electricity (for powering a central processing facility, or alternatively a burner to heat the boiler) and exhaust heat for heating the boiler.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of and priority to U.S. Provisional Patent Application Serial No. 62 / 050,894, filed Sep. 16, 2014, entitled “Produced Water Steam Generation Process Using Produced Water Boiler with Gas Turbine,” the contents of which are incorporated herein in its entirety for all purposes.FIELD OF THE INVENTION[0002]The invention relates to thermal recovery methods and systems for heavy hydrocarbon deposits, and specifically to such methods and systems requiring steam injection to mobilize the deposits.BACKGROUND[0003]In the field of subsurface hydrocarbon production, it is known to employ various stimulation procedures and techniques to enhance production. For example, in the case of heavy oil and bitumen housed in subsurface reservoirs, conventional drive mechanisms may be inadequate to enable production to surface, and it is well known to therefore inject steam or steam-solvent mixtures to make the heavy hydrocarbon...

AI Technical Summary

Benefits of technology

The present invention provides a system for generating steam from produced water with a simplified and value-added line-up that avoids heat transfer surface area duplication and minimizes the need for boiler feedwater treating.

Problems solved by technology

For example, in the case of heavy oil and bitumen housed in subsurface reservoirs, conventional drive mechanisms may be inadequate to enable production to surface, and it is well known to therefore inject steam or steam-solvent mixtures to make the heavy hydrocarbon more amenable to movement within the reservoir permeability pathways, by heating the hydrocarbon and / or mixing it with lighter hydrocarbons or hot water.

Conventional drum boilers operating at circa 2% blowdown cannot typically be used to generate steam from the produced water without using evaporators to generate high purity feedwater due to the concentration of dissolved salts and impurities such as calcium, silica, organics and the like that cause precipitation and thereby scaling within boiler tubes during the boiling of the water, which thereby very quickly renders the boiler ineffective in transferring heat to the water to generate steam and can also rupture boiler tubes due to the generation of hot spots.

For example, OTSGs still require boiler feedwater pretreatment, require large volumes of feedwater since much of the feed is rejected downhole as blowdown to manage impurities, and can suffer large amounts of downtime to clean boiler tubes (pigging).

However, alternative drum boilers require the use of evaporation technology, which adds significant capital expense and requires high energy consumption.

However, indirect boiling technologies currently under consideration are often complex and likely relatively expensive to implement as they may contain double the heat transfer surface area than what is required to generate steam alone.

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