The combustion efficiency of fully atmospheric oxidation is insufficient. Oil- and gas-flaring operations create significant amounts of emissions that contain unburned hydrocarbons, carbon monoxide and nitrogen oxides, which produce acid rain, smog, ozone at ground levels, and greenhouse gases in the upper atmosphere.
Acid rain depletes soil, pollutes water, damages forests, endangers animal habitats and food chains, and corrodes human-made structures, such as buildings, statues, automobiles, and other artifacts made of stone or metal. Smog and ozone cause human respiratory ailments, such as asthma, bronchitis and emphysema. Most scientists believe that greenhouse gases are a major cause of global warming. Increased concentrations of water vapor, carbon dioxide, methane and other greenhouse gases trap heat energy in the earth's atmosphere. A gradual rise in the earth's surface temperature is expected to melt polar ice caps and glaciers, expanding ocean volume and raising sea level, flooding some coastal regions and even entire islands.
Middle Eastern countries, including the U.A.E. with its low-lying coastal areas, are concerned about rising sea levels and potential flooding caused by global warming. They are concerned about increased radiation of heat and light from global warming, leading to regional desertification. As major producers of oil and gas, they are concerned about the deterioration of air quality from inefficient combustion of a sour gas supply.
Abu Dhabi is blessed with a charming environmental heritage. Nevertheless, the environment in this part of the world is no less fragile than anywhere else.
Recognizing mounting concerns over environmental issues, a joint task force was formed in June 1997. The Abu Dhabi Marine Operating Company and the Zakum Development Company, with the assistance of Schlumberger, the contracted service provider, worked together as one team to implement new solutions for optimizing acid neutralization, reducing flaring operations in the short term, and ultimately achieving zero hydrocarbon flaring to eliminate environmental risk during well-testing operations (1–3).
In an effort towards realizing ADNOC's HSE guidelines towards eliminating Oil and Gas flaring during testing and cleanup operations, a Phase Tester, Multiphase flowmeter was utilized offshore Abu Dhabi during clean-up and testing operations, leading to a reliable flow rate data, safer and more environmentally friendly operations. The deployment of the Phase Tester, Multiphase flowmeter lead to eliminating the gas flared by 100% during the post cleanup operations and thus decreasing the total amount of gas flared during cleanup and testing operations by 60–70%.
One of the reasons for flaring and/or partially flaring hydrocarbons during cleanup and testing operations is the relatively big pressure drop across the conventional testing equipment such as the separator. Such big pressure drop is inevitable to be able to separate the three phases. Because of the pressure drop, the usage of a boosting service and/or flaring the gas during the cleanup and testing operations is required.
By introducing a PhaseTester, Multiphase flow meter (Figure 1) to the system, most of these issues are eliminated. The extremely low-pressure drop across the meter helps eliminate any need to separate the phases and thus help to flow the well naturally through the production line without the need to flare the hydrocarbons.
The PhaseTester has been developed by Schlumberger and has been used successfully on more than 1200 jobs performed worldwide. The measuring principle is based on a total mass flow rate measured by a venturi meter, and the individual phase fractions measured by a dual energy gamma fraction meter. The Measuring Section contains the venturi meter and the dual energy gamma fraction meter.