Mixing oil and water

Oil and water have been companions for as long as oil has been produced in Alberta. Water is an essential element in oil field production. Over half of all oil produced in Alberta is developed using a production technique called ‘water flooding’. This involves injecting water into a depleting oil reservoir which helps to maintain the pressure in the field as well as sweep the remaining oil in the reservoir toward producing wells where it is pumped to the surface. As more oil is extracted through this process, a large percentage of water is also extracted and eventually, when insufficient oil is present, pumping is discontinued.

Although some of the water that is used in water flooding in oil fields in Alberta is fresh water, most of the water used today comes from salt water sources that are already contaminated by minerals. To further reduce new water requirements, the water that is recovered with the oil is separated and pumped back into the oil field. This allows the same water to be recycled many times, resulting in less fresh water use by the industry.

Cause for concern?

When the public hears that large volumes of water are being injected in Alberta’s oilfields, there is a perception that the oil industry may be depleting the province’s fresh water supplies. However government records indicate the larger water users in Alberta are the agriculture and electricity industries followed by municipalities. The oil and gas industry accounts for less than 2.5% of total water licensed each year and it actually uses only about half of this allocation. In fact, Alberta’s oil industry has continuously decreased its use of fresh water over the past 30 years. In the agricultural part of the province, fresh water use has decreased by 80% and in other parts of the province by about 60%.

There are also concerns that the oil industry uses a large percentage (up to 30%) of the licensed groundwater in Alberta. Although this is true, it should be noted that licensed groundwater represents only 1.3% of total licensed water use in Alberta and that the overall supply of groundwater is far larger than the supply of surface water (see chart on page 7). The policy that governs water use in Alberta has been in place since the 1930s and was most recently revised in 1999. Among other things, this policy addresses two important water supply issues. The first is that domestic water wells take precedence over industry use of groundwater and the second is that water allocation to industry must be done on a sustainable basis. It’s in everyone’s interest to use Alberta’s water resources wisely and to ensure their sustainability. The water practices of Alberta’s oil industry seem to reflect that theme.

Few organizations are as passionate about the debate over privatizing water services as the Canadian Union of Public Employees in Alberta. CUPE is concerned that poorly funded and under-resourced municipal water treatment systems are in danger of failing communities and that multinational water corporations are eager to take over ownership and control of community water supplies.

The fight to stop the privatization of water is a national priority within CUPE’s ‘Public Works!’ campaign. According to CUPE, when corporations sell water for profit, the quality, access and safety of municipal water supplies are endangered and the future of our water resources is threatened.

Virtually everything associated with the mining and processing of Alberta’s oil sands is big, and environmental consequences can be equally large. To get a clear picture of what all of this development means, the project proponents have established an industry-government-community organization called Cumulative Environmental Management Association (CEMA). CEMA has a mandate to identify a common development scenario using common data sets on background environmental conditions, as well as agreement on the approach and assessment tools that should be used. By using a common approach, project proponents, regulatory review agencies and public stakeholders will be able to more clearly understand the cumulative environmental impacts of these massive projects.

Another organization responding to the need for sound environmental research is the Canadian Oil Sands Network for Research and Development (CONRAD). CONRAD is a network of companies, universities and government agencies organized to facilitate collaborative research in science and technology for the Alberta Oil Sands industry. CONRAD’s goals include 1) improving the performance of the oil sands industry through superior new technologies, 2) improving the effectiveness and quality of oil sands research and 3) developing technologies that will further improve industry’s environmental performance. From the developers and regulators perspective, investments in oil sands projects are so large, and the financial impacts so critical, that all environmental consequences must be identified, understood and addressed in order to safeguard the viability of these projects.

The combined efforts of industry, government, universities and the public in the environmental aspects of oil sand development represent a unique initiative, by far the largest environmental research and assessment of any activity ever undertaken in Canada and quite possibly the world.

With Canada’s conventional crude oil production declining and much of the oilsands reserves being inaccessible to surface mining techniques, the oil industry has developed in-situ recovery methods. ‘In-situ’ means that the bitumen is extracted from the sands while physically leaving the latter undisturbed and minimizing surface environmental damage. EnCana has focused its energies in developing the estimated 30 billion barrels of heavy oil reserves at its Foster Creek and Christina Lake properties using the SAGD process.

In-situ recovery methods offer several advantages to the environment. Only about a fifth of the surface area needs to be disturbed as compared to surface mining techniques. Further, the steam that is injected into the injection well is recovered as water along with the bitumen from the oil production well. The water is subsequently reused to generate more steam for re-injection. Poor quality water can be used and therefore the demands on fresh surface water are minimal.

In addition to the environmental advantages, this technology will soon produce an estimated 170,000 barrels of oil per day for EnCana.

Production of natural gas from in-situ coalbeds isn’t a well known concept in western Canada but in some parts of the world significant quantities of natural gas are produced in this way. Coalbed gas accounts for about seven percent of the total natural gas produced annually in the United States and some Alberta-based companies including EnCana are closely following these developments.

Methane gas occurs as gas absorbed onto coal surfaces, as free gas in fractures and as gas dissolved in groundwater within the coal beds. To produce coalbed gas, the water in the coal must be removed by pumping, allowing the pressure in the coalbed to drop sufficiently for the gas to flow.

The quality of the water produced during coalbed methane recovery varies. In some cases water quality is such that it can be discharged onto the surface – in other cases the water must be treated or reinjected into the ground.

The processing of water associated with coalbed methane development is considered to be a major factor in developing this resource and is one of the factors oil and gas companies are addressing in their assessment of the potential of this new resource.

As Alberta’s conventional oil reserves decline, interest in developing Alberta’s huge oil sands reserves is increasing. Oil sands development presents unique environmental challenges, since it takes a lot of energy and water to get the thick, heavy oil out of the ground and separate it from the sand. Petro-Canada, a major oil sands player, is committed to ensuring that this development is done in an environmentally responsible manner. The corporation now applies a leading-edge technology that minimizes the use of water by recycling more than 90 percent of its water needs.

Oil sands have been mined from the surface since the 1970s, but only a relatively small part of the total oil sands reserves are shallow enough to be recovered by this method. Deeper oil sands reserves are known as ‘in situ’, and alternatives to surface mining have been developed to access these very substantial resources. Petro-Canada has been a leading proponent of steam-assisted gravity drainage (SAGD), an advanced technology that uses two long parallel wells drilled horizontally into the reservoir. Steam is injected into the upper well, heating the reservoir and mobilizing the bitumen (heavy oil) to flow into the lower well. The steam condenses back into water and flows back to the surface with the oil. SAGD enables recovery of about 60-80 percent of the oil in the reservoir, compared to 30 percent recovered by older in situ methods.

Petro-Canada began production at MacKay River, its first commercial SAGD project, late in 2002. Located 50 km northwest of Fort McMurray, MacKay River is expected to produce 30,000 barrels per day once it has reached full production.

Effective water use is a key environmental benefit of the SAGD technology. Any steam-assisted technology requires a significant amount of water to generate large quantities of steam. However, Petro-Canada’s goal at MacKay River is to recycle over 90 percent of all water used in a closed-loop system. Because SAGD has a better stream-to-oil ratio than other in-situ methods, it uses less energy and produces less greenhouse gases. At MacKay River no produced water is released back into the environment, and all make-up water is drawn from underground salty sources. From the earliest planning stages, Petro-Canada identified and implemented ways to reduce water use, drawing accolades from government and environmental groups.

EnCana operates the Weyburn oilfield which is one of the largest medium-sour crude oil reservoirs in Canada. The field is almost 50 years old. It has utilized waterflood for over 40 years and more recently infill and horizontal drilling to enhance production. A few years ago, a new recovery technology was introduced called CO2 miscible flooding.

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Apart from giving new life to an old field, the use of CO2 as a miscible flood agent makes this field Canada’s largest greenhouse gas sequestration project. The project has gained a lot of attention, in part because it offers such attractive oil recovery prospects but also because it permits the capture and disposal of a greenhouse gas that would otherwise be emitted into the atmosphere.