As pressure grows on oil and gas companies to limit the impact of their exploration and production (E&P) activities, producers are looking at new technology to develop greener practices.
Oil industry practices for safe operation and environmental protection have evolved significantly in recent years. As the US Department of Energy (DOE) points out, “this efficiency translates to smaller ‘footprints’ (the amount of surface area disturbed), less waste generated, cleaner and safer operations, and greater compatibility with the environment.”
A major factor promoting the use of greener practices is the cost oil and gas companies now incur because of various legislation on environmental protection. The US DOE estimates the American petroleum industry spends over US $9 billion each year on environmental protection and expects these costs to grow in the future.
Although the use of new technology cannot change geology, new information available to E&P companies about the features of the particular structure they are working on means the chance of finding oil and gas has risen. As poor prospects can be more easily eliminated before any drilling activity takes place, the environment of these areas is spared any activity – something that would not have happened in the past.
Drilling and production technologies in use today mean the lifetime of existing reservoirs can be extended, in some cases avoiding the need to develop new sites. They also permit E&P from remoter areas, where environmental damage may not have as great an effect as in areas of high population.
In addition, new directional drilling technology means companies can gain access to oil and gas resources in sensitive areas, such as wetlands, from an area nearby where a drilling site can be constructed with minimal effect on the environment.
Today, E&P companies can drill a single well from the surface, then turn the drill bit underground, to reach an oil or gas production zone miles away from the drill site. Multiple completions from the same wellbore can reach different oil and gas production zones and avoid disturbing surface ecosystems while smaller diameter holes and new drilling techniques are cutting wastes, noise, visual impacts, fuel consumption and emissions.
The DOE claims that because of technological advances, today, it takes 22 000 fewer wells annually in the US to develop the same amount of oil and gas reserves as it did in 1985. In the US, the size of drilling pads has been reduced by up to 80%: if Alaska’s Prudhoe Bay oil field was opened with today’s technology, its footprint would be almost one third of its current size.
Drilling fluid is a vital component of the rotary drilling process and plays a major role in completing a well safely and economically. It is a complex mixture of a fluid phase, a solid phase and a chemical phase. Environmental problems at the site are directly or indirectly related to the physio-chemical characteristics of drilling fluids.
Drilling fluid is the first foreign element that comes into contact with the reservoir zone of a wellbore and therefore has the potential to create the first environmental change to the area. As a result, deciding which fluids to use and where to use them is an important decision facing any E&P company. As a result, drilling fluid producers are researching the use of new additives such as polymers, clays and chemicals to create technically superior and more environmentally friendly products.
US company Halliburton via its Baroid Product Service Line, is a case in point. It has conducted research into using locally available natural resources as drilling mud additives and evaluating local agricultural resources to find similar or superior products. It is also studying the use of highly biodegradable oil-based and water-based muds.
In collaboration with the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) it has also developed new environmentally friendly water-based drilling fluids with high membrane efficiency.
“The CSIRO work was our first major foray into making a water mud perform like an oil based or synthetic based drilling fluid,” said Halliburton spokesperson Katy Eichelberger. “While we don’t currently offer a product or system that is the direct result of this effort, the knowledge we gained has been used to help in the development of our range of High Performance Water Based Muds.”
However, while she says Halliburton always “strives to provide drilling fluid solutions that fit the environmental demands of the markets in which they will be sold”, there is no single global definition of what constitutes ‘environmentally friendly’, or any single global set of environmental regulations or guidelines addressing drilling fluids. For example, potassium based additives will not pass toxicity limitations for the Gulf of Mexico – due to the particular species selected for toxicity tests being sensitive to potassium – but they are fine in the North Sea.
Many compounds are non-toxic, but do not degrade. Others have initial toxicity but degrade quickly so the effects are transitory.
“Certain regulatory bodies in different parts of the world may put emphasis on toxicity, while others focus on biodegradability,” said Eichelberger. “We try to balance these two factors in order to develop with what we believe are the best overall solutions, taking account of various regulatory requirements.”
In the absence of any global industry environmental standards, work continues to develop new greener fluids. As well as reducing the toxicity of the chemicals, Halliburton is also working on ways to reduce the quantity of material discharged to the environment.
“We have developed specialised, patented equipment such as our RotaVac™ fluids recovery system that recovers as much re-usable drilling fluid as possible from the drill cuttings prior to discharge,” said Eichelberger.
Another company, Baker Hughes Drilling Fluids, is also developing new products, in particular synthetic-based compliant emulsion systems for drilling in challenging downhole conditions, such as deepwater, high temperature, high-pressure wells. Driven in part by environmental legislation changes in the North Sea, these new products have brought with them superior performance in both diesel based fluids and in synthetic fluids. The company says “the chemistries chosen deliver minimal impact on the environment and to the health and safety of the personnel involved in the drilling operation.”
As well as drilling fluids, changes to other equipment used during the exploration process are being introduced. For example, researchers from the Sandia National Laboratories and General Atomics in the US and Russia’s High Power Battery Systems have developed a new fluoride battery (HTSS10V) for use in deep, high temperature drilling. At depths of 20 000 feet or greater, drilling tools can encounter temperatures of 200 degrees Celsius and the traditional use of lithium batteries is risky because they can explode at high temperatures and are a hazardous waste. This new battery, however, is operationally and environmentally safe.
New technology is revolutionising the way E&P activities are carried out. The ultimate aim is to have zero impact on the environment and there are signs this could become a reality. Norway’s Statoil’s 2005 drilling campaign by the Polar Pioneer rig on the Snøhvit field in the Barents Sea was, the company says, completed without any harmful discharges to the sea.
Factors driving the new environmentally friendly practices include pressure from shareholders and international environmental legislation, which means many energy companies now have to disclose the impact their operations have on the environments they work in.
“Environmental accountability today stands as one of the most important measures by which a company is regarded,” said Abdallah Jum’ah, Saudi Aramco’s president and CEO. “If an organisation is not active in safeguarding the earth’s natural resources, its best efforts in all other business areas are diminished. Indeed, the very perception of corporate attitudes toward environmental protection carries significant weight in the public’s trust of that company.”
And this is not going to change. In fact, E&P companies are likely to face more stringent environmental regulation in the future. This, Halliburton believes, will mean water mud will increasingly be favoured over oil mud in drilling fluids.
“To make this practical, the performance of water muds will have to improve to where they can compete with the performance of oil based from an economic as well as technical standpoint,” said Eichelberger. “There is still more development work to be done and this continues to be an important area of R&D focus.”
“We also expect to see continued development of the technology around waste management, cuttings handling, fluids recovery, reduction of actual quantities of drill cuttings and drilling fluids discharged to the environment, because just as oil muds will eventually be replaced more and more by water based muds, we expect the discharge of water based muds will likely become increasingly monitored and restricted just as oil and synthetic muds are today. Other technologies such as slim hole and mono bore well construction will increasingly have a role to play in reducing the environmental impact of drilling, by reducing the volumes of drilling waste generated.”
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