Crude oil occurs in many different forms throughout the world. An important characteristic of crude oil that affects the ease at which it can be produced is its density and viscosity. Lighter crude oil typically can be produced more easily and at a lower cost than heavier crude oil. Historically, much of the world's oil supply came from light or medium crude oil sources. Oil and gas companies are actively looking toward heavier crude oil sources to help meet demands and to take advantage of large heavy oil reserves located in many countries. Heavy oil includes very viscous oil resources like those found in some fields in California and Venezuela and oil (or tar) sands. In this paper, oil shale is also considered as heavy oil.
Produced water is the largest by-product associated with conventional oil production. The cost of managing large volumes of produced water is an important component of the overall cost of producing oil. Most mature oil fields rely on injected water to maintain formation pressure during production. The processes involved with heavy oil production often require external water supplies for steam generation, washing, and other steps. While some heavy oil processes generate produced water, others generate different types of industrial wastewater. Management and disposition of the wastewater presents challenges and costs for the operators. This paper describes water requirements relating to heavy oil production and potential sources for that water. It also describes how water is used and the resulting water quality impacts associated with heavy oil production.