Direct steam generation of boiler blowdown

Abstract

Systems and methods generate steam from produced water by passing the produced water through first and second steam generators coupled together. The first steam generator produces wet steam in which a liquid effluent with impurities of the produced water passes to the second steam generator. The second steam generator combusts fuel and oxidant in direct contact with the liquid effluent. The first and second steam generators limit fouling and waste while providing a combined steam output that may include combustion products from only the second steam generator.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Application Ser. No. 61 / 717,676 filed Oct. 24, 2012, entitled “DIRECT STEAM GENERATION OF BOILER BLOWDOWN,” which is incorporated herein in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]NoneFIELD OF THE INVENTION[0003]Embodiments of the invention relate to methods and systems of handling blowdown from initial steam generation with additional direct steam generation.BACKGROUND OF THE INVENTION[0004]Enhanced oil recovery processes employ thermal methods to improve recovery of heavy oils from subsurface reservoirs. For example, injection of steam into heavy oil bearing formations heats the oil in the reservoir, which reduces the viscosity of the oil and allows the oil to flow to a collection well. A mixture of the oil and produced water that flows to the collection well is recovered to the surfac...

AI Technical Summary

Benefits of technology

The patent describes a method and system for generating steam. The method involves injecting water into a steam generator to produce steam and a liquid effluent containing impurities. The liquid effluent is then injected into a direct steam generator to vaporize it upon contact with combustion products. The resulting gas phase includes additional steam and carbon dioxide, while the non-gas phase waste stream contains impurities. The system includes an initial steam generator, a direct steam generator, and an oil and water separation system. The method also involves recovering production fluid from a reservoir and separating it into an oil stream and a water stream. The water stream is then partially or fully vaporized while isolated from combustion products and further vaporized while in fluid communication with combustion products. The resulting steam is then injected into the reservoir for a steam assisted gravity drainage operation. The technical effects of the patent include efficient and effective generation of steam using a simple system and process.

Problems solved by technology

Several treatment processes remove constituents which form harmful deposits in the boiler or steam generator but without even further costs do not remove all dissolved solids.

The blowdown presents a problem regardless of application requiring the steam.

The impurities can limit reuse as feedwater without further expensive treatment or inefficient concentrating of the impurities.

If not reused, the blowdown represents a significant and unacceptable water portion for disposal.

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