Geological and petroleum technicians typically do the following:

• Install and maintain laboratory and field equipment
• Gather samples such as rock, mud, and soil in the field and prepare samples for laboratory analysis
• Conduct scientific tests on samples to determine their content and characteristics
• Record data from tests and compile information from reports, computer databases, and other sources
• Prepare reports and maps that can be used to define geological characteristics of areas that may have valuable resources
• Monitor well exploration activities and record data such as well temperatures and pressures
• Document their investigations and compare actual productivity with their estimates

Geological and petroleum technicians tend to specialize in either fieldwork and laboratory work, or working in offices where they analyze data. However, many technicians have duties that overlap into multiple areas.

In the field, geological and petroleum technicians use sophisticated equipment such as seismic instruments to gather geological data. They also use tools to collect rock samples and other materials for scientific analysis. In laboratories, these technicians analyze the samples for evidence of hydrocarbons, useful metals, or precious gemstones.

Geological and petroleum technicians use computers to analyze data from samples collected in the field and from previous research. They use Geographic Information Systems (GIS) software to map geological data; the software creates a visual representation and makes the data easier to understand. The results of their analysis may explain a new site's potential for further exploration and development or may focus on monitoring the current and future productivity of an existing site.

Geological and petroleum technicians work on geological prospecting and surveying teams under the supervision of scientists and engineers, who evaluate the work for accuracy and make final decisions about current and potential production sites. Geologic and petroleum technicians might work with scientists and technicians in other fields as well. For example, geological and petroleum technicians might work with environmental scientists and technicians to monitor the environmental impact of drilling and other activities.