Removal of Oil from Produced Water by Coalescence/Filtration in a Granular Bed

Abstract

Oil production generates a significant amount of water byproduct known as produced water. Following primary gravity separation, produced water is normally disposed of by injection into the formation from which it came. However, high amounts of suspended solids or oil in the produced water may cause clogging of the injection formation. This study evaluated the effectiveness of coalescence/filtration in treating two produced water samples obtained from Saskatchewan heavy oil production sites. In the coalescence/filtration experiments, percentage removals of oil and suspended solids were observed to be as high as 97 and 91 percent, respectively. Mechanisms of filtration and coalescence were identified and observed through experimental data and mathematical models. The maximum coalescence efficiency observed was three percent at the lowest flow rate. Coalescence efficiencies decreased with increasing flow rate. Experimental data for single and two-phase flow were shown to fit the Carmen-Kozeny filtration equation. Coalescence/filtration satisfied a first order rate equation using the Crickmore model.

Effect of fibrous filter properties on the oil-in-water-emulsion separation and filtration performance

“…These coalesced oil droplets are then big enough to float at the filtrate surface and to be separated easily. Thus similar to the findings of other authors [6][7][8]14], for the coalescence filtration, the coalescer surface should also be preferably wettable by the dispersed phase but not by the continuous phase.…”

“…10). Similar to the findings of other researchers [1][2][3][4][5][6][7][8][9][13][14][15][16][17][18][19] for effective phase separation, a coalescer medium (thick/thin) should be preferably wetted by the dispersed phase and possess high porosity and small pore size. …”

“…However, the opinions differ on the effect of filter media surface wettability on emulsion separation. For the emulsion separation by means of coalescence, some authors concluded that the dispersed phase should readily wet the fiber surface [6][7][8]14], while others concluded that it should not [4,15], yet some have resolved that wetting behavior of the dispersed phase is unimportant and/or intermediate wetting conditions are required [13,[15][16][17][18].…”

Effect of the Mixed Oleophilic Fibrous Coalescer Geometry and the Operating Conditions on Oily Wastewater Separation

“…Most kinds of industrial wastewater contain O/W emulsions among their basic contaminants [4]. Various physical methods are used for oil-water separation, such as gravity separation, parallel-plate separation [5], air flotation [6], hydrocyclone separation [7], centrifugal separation [8], filtration [9], micro-and ultrafiltration [10,11], electric field separation [1,12], ultrasonic separation [13,14], and membrane separation [15,16]. These methods can separate free and dispersed oil droplets in wastewater efficiently and economically.…”

Separation of Oil Phase from Dilute Oil/Water Emulsion in Confined Space Apparatus

“…Conventional separation techniques for oil/water emulsion involve gravity settlers [5,6], chemical methods [7][8][9], physical fields (electric field [10,11], acoustical [12], centrifugal [13], etc), air flotation [14,15], porous medium filtration and coalescence (porous beds [16][17][18][19], membranes [20][21][22][23][24]), etc. Gravity settlers are often ineffective for the emulsion with small droplets.…”