Abstract

One of the by-products of oil producing activities is formation water. With the increasing public awareness of environmental protection, many oil companies including LASMO Oil (Malacca Strait) Ltd, have placed a greater emphasis on the close surveillance and monitoring of discharged water. This paper reports the results of monitoring programs on effluent water produced by three of LASMO Oil's major fields (Lalang, Kurau and Melibur) in the Malacca Strait area, which is noted for its dynamic tidal forces. The study focused on the impact of the high temperature discharged water containing phenol and hydrocarbon residue on the aquatic environment.

The study concluded that there were essentially insignificant physical or chemical changes in the aquatic receiving environment occurring 200 meters upstream and downstream of the discharge pipes. Phenol was undetectable in all bottom sediments and receiving waters. Dispersed hydrocarbons (>10 microns) were detected in receiving waters and in bottom sediments in small concentrations. The temperature difference between the discharged water and sea water at a distance of 5 meters from the outfall pipe is insignificant. The location of the discharge pipes relative to receiving water affects the dissipation of temperature and hydrocarbon content. In addition, the high energy of the Lalang Strait resulted in the rapid dilution of discharged water and significantly reduced temperature, phenol and hydrocarbon concentrations in the sea water.