This study investigated the fouling behavior and chemical cleaning of forward osmosis (FO) membranes for treating produced/process water (PPW) from a real gas field using thin-film composite FO hollow fiber membranes. Experiments revealed that membrane fouling occurred during the PPW treatment, which hindered the water and solute transport through the membrane. The water permeability and FO reference water flux of the membrane decreased by 22.9% and 24.8%, respectively, after fouling. Membrane surface characterization was carried out, and the results indicated the deposition and entrapment of organic species on the membrane after the PPW treatment. The efficiencies of various cleaning agents, induding sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic (EDTA) and NaOH, were evaluated. It was found that cleaning with SDS for 15 min is the most effective method for restoring water flux, and very stable FO performance can be obtained during batch treatment of PPW. The FO membrane can reduce the PPW volume by 50% at a relatively high average water flux of 15.6 L.m(-2).h(-1) in the active layer facing feed solution orientation using 1 M NaCl as draw solution (equivalent to the draw solution available in the field). This study demonstrates the great potential of FO technology for produced/process water treatment. (C) 2016 Elsevier B.V. All rights reserved.