Oil wells have traditionally used oil-based and synthetic fluids to help prevent wellbores from collapsing, to cool and lubricate drills and to keep out extraneous material. Such fluids can pollute the ocean and there is increasing pressure to have them banned.
"Collapsed and sidetracked oil wellbores, lost tools and abandoned wells cost the global oil and gas industry $2 billion annually and there is an urgent need for a new generation of water-based drilling fluids," says CSIRO scientist Dr Chee Tan.
"The new 'green muds' are an efficient, low-cost, water-based alternative that are hydrocarbon-free and designed to reduce drilling costs and improve oil well performance."
Shales, mudstones, siltstones and claystones account for 75 per cent of drilled sections in oil, gas and geothermal wells and cause about 90 per cent of wellbore instability-related problems during drilling operations, says Dr Tan.
The new 'green muds' have special polymers which 'coat' the wellbore surface to prevent extraneous fluids destabilising the well, are as efficient as traditional methods, are more cost-effective and can be applied within existing environmental standards.
"The 'green muds' also have the potential to reduce the number of oil wells," says Dr Tan. "They will be particularly useful for operators of long reach oil wells that must maintain a delicate balance between drilling fluid pressure and
rock stresses over lengthy periods.
"By helping oil companies drill successfully and economically, 10 kilometres or beyond, fewer platforms will be needed to exploit an oil field."
A world patent is being processed and field trials are being discussed with oil companies with wells in the South China Sea.
Evaluation of the 'green muds' with cuttings and downhole cores from the region clearly demonstrated the superior shale inhibition performance of the muds over other water-based muds. In addition, laboratory testing is currently being conducted on a troublesome shale from the Middle East. Interest has also been expressed by companies in Australia, Malaysia, Brunei, United Arab Emirates, China and Japan.
The 'green muds' formulations are being commercialised by Baroid as the BarOmegaTM (Osmotic Membrane Efficiency Generating Aqueous) drilling fluid system.
The new substances have been jointly developed by a team of CSIRO Petroleum scientists working at ARRC (the Australian Resources Research Centre in Bentley, Western Australia) in conjunction with US firm Halliburton Energy Services' Baroid Drilling Fluids.
The ARRC is located in Perth's Technology Park and houses CSIRO's Exploration and Mining Division, Curtin University of Technology's Department of Exploration Geophysics, Centre of Excellence in Petroleum Geology and Department of Petroleum Engineering.
