Water Supply and Effluent Disposal Challenges in the Egypt / Middle East Oil Industry
On a global basis, oil companies produce approximately three times as much water as oil, in upstream operations; some 250 million barrels per day. That is water coming to surface in oil producing wells, and hence it is usually referred to as produced water, or sometimes as effluent water. Oil companies often reuse that water for injection back into oil reservoirs, for reservoir pressure maintenance (and this is usually termed produced water re-injection, or PWRI). Alternatively, it may be disposed of by discharge to sea, rivers or lakes, or by underground injection into zones or aquifers at shallower depths than the source oil reservoirs, i.e. disposal wells not PWRI wells.
In the upstream oil and gas industry, water is also used for:
- Desalting of crude oil, i.e. washing salt or highly-saline water out of oil using ‘fresh’ or low-salinity water, often obtained from a shallow aquifer.
- Process cooling; perhaps using seawater or again a shallow aquifer or river water.
- Water injection for reservoir pressure maintenance, using seawater, aquifer water or river water, prior to implementing PWRI.
- Process water; for wash-down, making up chemical solutions e.g. drilling fluids.
- Potable water; for drilling rigs, construction camps, offices and accommodation; perhaps from shallow aquifers, rivers or desalination of sea¬water or saline aquifers.
Water is used for many similar duties, often in great quantities in downstream oil processing, typically creating large amounts of slightly contaminated wastewaters, and at many intermediate stages in pipeline hydro- testing, tanker ballast waters, and so on. However, in this short article I will focus on challenges in water supply, processing and effluent disposal facing the upstream oil industry in the Middle East, which are:
- Achieving the optimum ‘handling’ of increasing volumes/flow-rates of produced water which inevitably comes with more ‘mature’ oilfields. Handling involves the design, construction, operation and maintenance of production wells, flowlines / pipelines and the oil, gas, and water processing facilities, through to water reuse or disposal.
- Achieving the appropriate care for the environment, in overall terms, perhaps expressed as the Best Practicable Environmental Option (BPEO), and with consideration given to short, medium, and long-term time- scales. The latter may be for 100 years, or more, if comparisons are made with environmental liabilities now being enforced for some other industrial pollutants such as asbestos, radioactive wastes, and cognizant of possible climate-change issues. These outline challenges are expand¬ed upon below, with particular focus on the characteristics, effects, and treatment of oilfield produced waters.