Petroleum engineers typically do the following:

• Design equipment to extract oil and gas in the most profitable way
• Develop ways to inject water, chemicals, gases, or steam into an oil reserve to force out more oil
• Develop plans to drill in oil and gas fields, and then to recover the oil and gas
• Evaluate the production of wells through testing and surveys
• Use computer-controlled drilling or fracturing to connect a larger area of an oil and gas deposit to a single well
• Make sure that oil field equipment is installed, operated, and maintained properly

Oil and gas deposits, or reservoirs, are located deep in rock formations underground. These reservoirs can only be accessed by drilling wells, either on land or at sea from offshore oil rigs.

Once oil and gas are discovered, petroleum engineers work with geoscientists and other specialists to understand the geologic formation of the rock containing the reservoir. They then determine the drilling methods, design the drilling equipment, implement the drilling plan, and monitor operations.

The best techniques currently being used recover only a portion of the oil and gas in a reservoir, so petroleum engineers also research and develop new ways to recover more of the oil and gas. This helps to lower the cost of drilling and production.

The following are examples of types of petroleum engineers:

Completions engineers decide the best way to finish building wells so that oil or gas will flow up from underground. They oversee work to complete the building of wells, which might involve the use of tubing, hydraulic fracturing, or pressure-control techniques.

Drilling engineers determine the best way to drill oil or gas wells, taking into account a number of factors, including cost. They also ensure that the drilling process is safe, efficient, and minimally disruptive to the environment.

Production engineers take over wells after drilling is completed. They typically monitor wells' oil and gas production. If wells are not producing as much as expected, production engineers figure out ways to increase the amount being extracted.

Reservoir engineers estimate how much oil or gas can be recovered from underground deposits, known as reservoirs. They study reservoirs' characteristics and determine which methods will get the most oil or gas out of them. They also monitor operations to ensure that the optimal levels of these resources are being recovered.