Oil majors work at reducing water use in desert state

The Royal Dutch Shell Group and Petroleum Development Oman have started work on reducing their water and wastewater environmental footprint for operations in Oman.

At present, Shell and PDO use more than 800 wells to abstract water from shallow aquifers, using the water for industrial purposes and to provide domestic supplies to employees and local communities.

Oil extraction in the country produces more than 700,000 cubic metres per day of water, which is likely to increase to over one million cubic metres by 2015. A further 55,000 cubic metres is abstracted from aquifers for us in industries related to oil production and for domestic supplies.

However, the World Council for Sustainable Development has reported, as part of its case studies into industrial water use, Collaborative actions for Sustainable Water Management, on efforts by the companies to reduce this usage considerably.

The two groups have put the following hierarchy of management principle in place to minimise cost and maximise value to turn wastewater into a resource:

  • minimise volume produced;

  • maximise reuse of production water;

  • phase-out shallow disposal wells into aquifers;

  • return water to producing oil reservoirs;

  • dispose surplus water to producing oil reservoirs.

    Applying these principles has prompted innovation such as re-injecting the extracted water to increase oil reservoir pressure which improves the efficiency of oil extraction.

    The two companies are also working on ways to separate the water coming out of the oil reservoir while still underground in the well bore or at the wellhead. For example, using cyclone-based technology has reduced the cost and energy intensity of the separation which otherwise has to take place at the surface with conventional technologies.

    Shell and PDO have also developed innovative approaches for re-use of water once it reaches the surface. For example, they constructed a pilot facility channels water through reed beds to improve purity, after which it is acceptable for irrigation of certain salt-tolerant crops.

    Previously, surplus production water was disposed through wells into shallow aquifers. This is now being phased out to avoid polluting the ground water, thus ensuring it is available for future use.

    The sustainability of the water supply schemes was analysed using hydro-geological model and indicate that natural replenishment matches demand so the necessary water supplies can be maintained for the foreseeable future.

    This approach has also been integrated in Oman’s national water management plan and has been selected also as an example for best practice sharing in the oil industry’s “Water Management Good practice Guidelines”.

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