Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Investigation on Electromagnetic Separation of Produced Water in Oilfield
LZ Zhao1,2; XL Feng1,2; XQ Chen1; AW Peng1,2
1. Laboratory of Renewable Energy Generation Technology, Institute of Electrical Engineering Chinese Academy of Sciences
2. School of Engineering Science, University of Chinese Academy of Sciences
Beijng, China

used in the deep treatment of oily sewage (Ahmadun et al, 2009; Chenet al., 2019; Yu et al 2013). At present, the treatment of produced water
is more and more difficult. It is almost impossible for a single oil-water
separation method to meet the increasing separation requirements, andmultiple methods are combined to achieve cost-effective separation
results (Su et al., 2019). And many new methods have been proposed
and used to improve the effectiveness, efficiency and environmental
friendliness. An environmentally friendly and recyclable biofilm withimmobilized cells of P.aeruginosa NY3 was developed for the treatmentof produced water with high salinity and low pH (Nie et al, 2020). Oilwell produced water was treated by a biochemical double membraneprocess in Shenli Oilfield and the oil content of produced water after
biochemical treatment was 0.63 mg/L (Pan et al, 2021). Lu and et al(2021) applied the thermochemical cleaning method first to treat thepolymer-containing produced water and got an average oil recovery rateincreased by 20%. A novel liquid-liquid extraction and efficient phaseseparation in a mixer-settler based on phase inversion was put forward,
the oil and grease removal from real offshore produced water samples
was evaluated and a final outlet stream containing oil and grease under
29 mg/L was got (Ana Caroline Klemz et al, 2021).

ABSTRACTElectromagnetic separation provides a new way to treat oilfield produced
water. In this paper, the process of electromagnetic separation of oilfield
produced water is analyzed theoretically and numerically, and theseparation characteristics are investigated when TOC is 103 ppm and theviscosity and size of oil droplets are 100 Pa.s and 101 μm, respectively.
The results show that: 1) the electromagnetic separation of oilfield
produced water has advantages of supergravity separation and air
flotation separation, and the separation efficiency is high; 2) with thesame supergravity coefficient, the treatment capacity of produced water
increases with the size of oil droplets increasing, and decreases with
TOC and the viscosity of oil droplets increasing; 3) the flow rate ofdischarged water increases with the increase of the supergravity
coefficient and oil content of discharged water; 4) the flow rate ofproduced water, that is ,the treatment capacity of the separation channel
increases with the increase of the supergravity coefficient.

KEY WORDS: Oilfield; produced water; mixed flow; magnetic field;
electric field; oil-seawater separation.

Produced water contains mainly dispersed oil which is conveyed as Total
Oil Content (TOC) and inorganic salts which are conveyed as Total
Dissolved Salts (TDS). TDS is closely related to the electric conductivity.
In China, produced water in many oilfields has high TDS up to 104-105
mg/L (Li, 2014; Fan, 2021). For example, TDS of the oil well produced
water in Shenli Oilfield is 18100 mg/L with an electric conductivity of30348 μS/cm (Pan et al, 2021). So electromagnetic separation which uses
electromagnetic force to separate conductive and non-conductive
substances can be applied to treat produced water in oilfields.
Electromagnetic separation has been applied in metal purification andmetal matrix composite preparation (Han et al, 2021; He et al, 2020; Renet al, 2020), removal of heat stable salts from industrial lean amine
solutions (Abdul Hai et al, 2020), pea protein concentrate (Zhu et al,2021), marine oil spill and ship oil sewage treatment (Sha et al, 2007;
Zhang et al, 2007; Ye et al, 2013; Peng et al, 2014; Liu et al, 2015; Zhaoet al, 2015; Zhao et al, 2018). Bian (2015) first applied electromagnetic

INTRODUCTION
Nowadays, the exploitation of most oilfields in China has been enteredin the middle and late stage with a comprehensive water content morethan 80% or even more than 90%. Water drive, thermal recovery, steam
flooding, chemical flooding and other methods have been used, resulting
in the complexity and variability of produced water. And in producedwater, the water phase exists in the form of free water, and the oil ismixed into the water phase mainly in the form of dispersing small oil
droplets of 20-150 μm. There is also a small content of emulsified oil of
5-20 μm in produced water (Almeida et al, 2019; Kundu et al, 2018). For
the separation of free water, it can generally be achieved by gravity
sedimentation and centrifugal separation (Yang et al, 2021). For theemulsions, the first thing to do is to demulsify and heating, chemical andelectric de-extraction methods are usually used. The membrane
separation, air flotation, flocculation, adsorption and filtration have been

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