Water production from oil and gas fields has been more and more increasing globally, and thus the treatment and the reuse of produced water has become one of the top issues in oil and gas industry. Produced water re-injection (PWRI) to reservoirs for pressure maintenance or water flooding is an environmentally-friendly scheme over disposal options. Because solid particles, bacteria, as well as residual oil can cause plugging of the pores in the formation rock resulting in deterioration of oil recovery, PWRI to "tight" or low permeable reservoirs requires high levels of removal of these constituents. In addition, there is also a growing interest of removal of dissolved salts from the produced water for the beneficial reuse. This also requires an advanced filtration as pretreatment to desalination by reverse osmosis (RO) or evaporation. For both of these applications, microfiltration (MF)/ultrafiltration (UF) technologies using ceramic membranes are considered as a very effective solution because ceramic membranes offer high hydrophilicity, relatively low fouling by oil-in-water, and broad chemical and thermal compatibilities. An industrial scale produced water treatment demonstration plant has been installed in an oilfield to test the performance of ceramic MF membranes. The plant includes a crossflow filtration system which accommodates commercial ceramic membranes (180mm Dia., 1,500 or 1,000mmL) followed by RO equipment. The demonstration test was performed for seven months in 2017. Through the seven months of the field demonstration, protocols for sustainable operation were developed under field conditions in which feed water qualities varied very widely in terms of concentration of oil & grease and other foulants. The filtrate contained suspended solids (SS) and oil & grease not higher than 1 mg/l and 10 mg/l, respectively, at all times during the test period. Therefore, it has been proven that the ceramic membrane filtration can be very effective for alleviating plugging risk when applied to PWRI in tight reservoirs. Silt-density-index (SDI) of permeate, an indicator of RO feed water quality was not higher than 3.0 and the average was 1.6; this indicates the membrane-filtered water is appropriate for the RO feed.

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