Optimal selection of an integrated produced water treatment system in the upstream of oil industry

Abstract

Abstract Produced water (PW), water extracted along with oil, can cause important environmental challenges due to its high volume and salinity and is considered a key factor in the economic exploitation of oil fields. Therefore, making use of a cost-effective integrated system of wastewater treatment is a fundamental requirement in oil and gas industries. In this paper, the integrated PW treatment system is presented using superstructure-based mathematical optimisation methodology which is aimed at minimising the total annual cost. Two distinct scenarios of injection and reuse in industrial scale are considered to propose an efficient and optimal integrated system. The results show that, despite the emergence of new technologies, the traditional ones such as gravity separation, hydrocyclone, and media filters, with a cost of $0.509 per cubic meter, are selected as the optimum solution for treating PW for injection purpose. Because of the poor quality of PW in Iran, reuse options are limited, and the efficient available technologies are few. Mechanical Vapor Compression (MVC) and Multi Effective Desalination (MED) technologies are investigated as two desalination options. According to the findings, a treatment system composed of MVC with appropriate pretreatment is capable of recovering 50% of the PW, which is the optimal water recycling option with a total treatment cost of 3.808 $/m3. In cases of increasing the volume of PW with time, it is concluded that utilising advanced treatment system to recover a part of PW, decreases the annual cost up to 20% in comparison with the case which increases the PW injection capacity. This can be considered as a more viable management strategy for PW management in future.