Examination of produced water from the Al-Hamada oilfield, Libya.

Produced water is generated to the surface from oil production. Because of the complex composition of produced water (a mixture of different organic and inorganic compounds and residues of oilfield chemicals - added to aid oil water separation) and due to the outcome of increasing volume and effect of discharging, its analysis has become a significant issue of environmental concern. For this purpose and also because of concerns over health and its safety, the chemical compositions of four produced water samples from Al-Hamada oilfield in the Libyan Arab desert were investigated in details. The physical-chemical properties included pH,TDS, EC, COD, cations and anions, organic compounds TOG, TPH, Base/Neutrals acids, Total phenols, BTEX, PAH carbon distribution of the oil extracted from the samples, inorganic compounds (heavy metals), added chemicals (corrosion inhibitor and biocides). Determinations were carried out using techniques, such as, GC-FID (HS-SPME), GC-MS, (ESI-MS/MS) and (LC-ESI-MS). The results indicate that the metals were within the expected natural ranges compared to those mentioned in the literature. Only manganese values were found to be higher than those in the literature in a range between 0.06-0.23ppm. BTEX and phenol were within range, 0.1- 0.2 and compounds acenaphthene, indeno(1,2,3-cd)pyrene, benzo(b)fluoranthene of PAH were identified in the range between0.4-2ppm. These originate could be from biodegradation by existing bacteria, which generally changes the chemical composition and reduce the toxicity of the water. Typical corrosion inhibitor chemicals quaternary ammonium compounds (quats) were detected with alkyl chain lengths of C12 (m/z 304), C14 (m/z 332), C16 (m/z 360) and C18 (m/z 388). On the whole, knowledge is needed about the level of oilfield chemicals in the produced water and groundwater and also phenol and alkyl phenols compound present that contribute to the environmental impact of produced water need to identify by GC-MS. Produced water should not be consumed by humans and animals.