Petrophysics MSc Course Notes by Dr. Paul W.J. Glover

Searching for Economic Accumulations of Oil and Gas

• The first step in the search for economic accumulations of oil and gas is not specified, but it likely involves exploration and data collection.

Logging Tools

• The caliper log is used to evaluate the borehole environment.
• The neutron log primarily measures the porosity of a formation.
• The density log is used to measure the formation density.
• The sonic log primarily measures the formation's acoustic velocity.

Petrophysics

• The primary purpose of resistivity theory in petrophysics is to understand the flow of electric current through a formation and its relationship with the formation's fluid saturation and rock properties.
• The primary function of the total gamma ray log is to measure the natural radioactivity of a formation.
• The main purpose of capillary pressure in petrophysics is to understand the relationship between the pore throat size and the corresponding capillary pressure.
• The main purpose of fluid testing and pressure logs is to obtain information about the formation fluids and their pressures.

Roles and Responsibilities

• The primary responsibility of the exploration geologist is to find potential areas with economic accumulations of oil and gas.
• The main responsibility of the petrophysicist is to analyze sub-surface formations and provide information about the formation's properties and fluid saturation.
• The petrophysicist and geologist both play a significant role in carrying out initial reservoir modeling.
• The geologist's main influence in evaluating sub-surface formations is in providing information about the formation's geological structure and properties.

Data and Information

• The main database of information available to both the geologist and petrophysicist is the well log data.
• Clay has a significant influence on resistivity and porosity in petrophysics, as it can affect the formation's electrical properties and fluid flow.