Water Used for Oilfield Injection Purposes
(Updated July 2010)
To produce oil, water is sometimes pumped into an oilfield causing more oil to move towards wells producing oil. This process, called oilfield injection, helps to maintain higher pressure, which in turn helps to maintain production. Water may also be heated and injected as steam into bitumen causing the oil to flow to the producing wells. Groundwater (saline and non-saline) or surface water from rivers or lakes can be used for oilfield injection.
Most uses of water, whether it be for municipal, agriculture, industrial or commercial, result in an amount that is not returned to the local ecosystem. With oil recovery, injected water mixes with naturally occurring water in oil reservoirs and the mix is re-injected many times. The water that is injected into an oilfield remains in the formation and is no longer readily available for other uses.
Although oilfield injection is not the largest water user in the province, Albertans have expressed concern over this practice. Projections indicate that water use for oil recovery could increase significantly in the future.
What does the indicator show?
Fresh surface water and non-saline groundwater have typically been used for conventional oil recovery schemes. Use of fresh water sources has been gradually declining as fewer conventional oilfields remain to be developed. The oil industry has also improved water efficiencies and recycling. This means that process improvements are reducing the amount of water required to produce a barrel of oil.
Trend: Total water use is increasing with the majority coming from saline water sources. The trend in total fresh and non-saline water use is relatively flat.
This indicator tracks the use of water for oilfield injection over time. The purpose is to assess whether conservation, improved efficiencies and technological changes are resulting in less reliance on fresh water sources and water in general. Three types of source water are identified as solid colour lines - surface water, non-saline groundwater, and saline groundwater. The totals are shown as dashed black and grey lines.
Usage of non-saline groundwater has remained relatively consistent over time, while usage of saline groundwater is increasing as the demand for thermal oil sands recovery is growing. Older thermal recovery schemes have typically relied on a combination of fresh surface water and non-saline groundwater supplies as their source waters. In recent years, most new projects have attempted to use more saline groundwater.
After remaining fairly steady for the last 25 years, overall source water use is trending upward. Increases in use of water in oil sands are offsetting declines in conventional recovery schemes. Reliance on fresh water sources has been declining but has leveled off in recent years. In 2007, saline groundwater became the largest single source type of water used for oil recovery at 40 per cent, up from 10 per cent just 15 years ago.
Relative Use of Saline and Freshwater Sources
Another way to look at oilfield injection data is to consider the relative proportion of each type of source water used. The total volume of injected water has fluctuated for the past twenty-five years between roughly 47 and 60 million cubic metres per year.
Growth in oil sands has contributed to an increasing trend since 2002. However, as shown in the chart below, the type of source water used is changing from fresh sources towards saline groundwater sources. Until the mid-1980s, saline groundwater was typically less than three per cent of the total volume of water used to recover oil. Recently, that number has reached more than 40 per cent.
What actions are being taken?
Following the consultations for Alberta's Water for Life Strategy, Alberta Environment commissioned a report to determine actual water use for oilfield injection purposes in Alberta. The Minister's Advisory Committee on Water Use Practice and Policy was created to examine how use of water should be addressed into the future. Recommendations from the advisory committee resulted in a Water Conservation and Allocation Policy and Guideline for Oilfield Injection.
Links to additional information:
- Water Conservation and Allocation Guideline for Oilfield Injection 2006
- Final Report of the Advisory Committee on Water Use Practice and Policy
- Water and Oil: An Overview of the Use of Water for Enhanced Oil Recovery in Alberta
- Petroleum industry information on water and environment (Canadian Association of Petroleum Producers)
Alberta's oil industry extracts large volumes of oil using basic, conventional technologies where oil flows either to the surface under its own pressure or is lifted by pumps in the wellbore. Over time, pressure in oil formations will decline as oil is removed. To continue to recover more oil, enhanced recovery methods become necessary.
These methods involve pumping water or another substance, such as carbon dioxide, into the formation to displace oil to producing wells and then to the surface. Water is the most common substance used to displace oil. In the case of thermal oil recovery, which is used in some oil sands projects in northern Alberta, water is heated to create steam. Steam is injected to heat the sticky oil (bitumen) and make it thinner, enabling the oil to flow more easily to producing wells.