Method of using contaminated water from an oilwell effluent stream

Abstract

A method of using contaminated water from a well effluent stream produced by oil wells to produce biofuel and / or other biochemical compositions comprises: a) separating the well effluent stream in an oil-water separator assembly into a crude oil stream and a contaminated water stream with capped fractions of contaminants, such as crude oil, salt and metals; b) feeding at least a fraction of the contaminated water stream (1) to an irrigation system (2) of a cascaded series of soil beds (4) in which at least one saline tolerant cellulosic crop (5), such as reed, eucalyptus trees and / or tamaris, is planted, which cascade of soil beds acts as a cascaded biological filter for stepwise further reduction of the crude oil and metals content of the contaminated water stream; c) growing the cellulosic crop or crops (5) on the soil beds, wherein the contaminated water stream (1) is used to irrigate and mature the cellulosic crop or crops (5); d) harvesting a mature cellulosic crop (5) from at least one of the soil beds (4); and e) converting cellulosic material in the harvested mature crop (5) into a compound of a biofuel and / or other biochemical composition by a chemical conversion process.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to a method of using contaminated water from a well effluent stream produced by oil wells traversing a crude oil and contaminated water containing earth layer.[0002]In many oilfields the produced well effluent streams comprise more water than crude oil. The produced water is often brine, which is contaminated, inter alia, with metals, dissolved salts, organic chemical constituents and hydrocarbons, and which cannot be currently purified economically into fresh water.[0003]It is known to separate contaminated water from a well effluent stream produced by a cluster of oil production wells in a bulk oil-water separator and to subsequently re-inject the contaminated water into the earth.[0004]It is also known to use contaminated water derived from crude oil production for irrigation purposes from SPE paper 88667 “Opportunities for re-use of produced water around desert oil fields” presented by A. C. Sluijterman et al at the 11th Abu...

AI Technical Summary

Benefits of technology

[0020]The irrigation system of the first of the cascade of soil beds may comprise an irrigation water discharge system, in which unused irrigation water that has been passed through the soil of the first soil bed and of which the crude oil content has

Problems solved by technology

The produced water is often brine, which is contaminated, inter alia, with metals, dissolved salts, organic chemical constituents and hydrocarbons, and which cannot be currently purified economically into fresh water.

A problem with the method described in the above SPE paper of using contaminated water derived from crude oil production for irrigating a reed bed is that the reed crop grown may have a changing composition and may contain contaminants which have thus far inhibited the use of the produced crop for consumption by humans (food) or animals (fodder).

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