Petrophysicists working for oil companies have an integral role within the subsurface characterization discipline. Their main task is to quantify and characterize the rock and fluid properties of a reservoir by analysis of the pore space between a rock grains, how these spaces are connected and what the fluids in the rock are. This is done mainly through the interpretation of logging data and core data. Logs can be run on wireline, in open or cased hole or run behind the drilling assembly whilst drilling and are designed to measure various physical properties of the rock such as their natural gamma ray signature or electrical properties. The petrophysicst will usually design and oversee the logging and coring program to ensure optimal and efficient data acquisition to address subsurface uncertainty. The petrophysicst assists the geologist and reservoir engineer in populating the static and dynamic field models.
Petrophysicsts may be responsible for:
- Determining formation properties including lithology, porosity, saturation, permeability and net pay through well log and core data interpretation.
- Designing the objectives of a logging program for wells.
- Ensuring an up to date knowledge of logging and coring technology.
- Monitoring data during acquisition to ensuring the quality of data and holding service companies accountable for their performance.
- Providing petrophysical input to geologists for static modelling, engineers for dynamic modelling and also to geomechanical and geophysical models.
- Determining the objectives of a coring program. Selecting samples for further analysis and overseeing the core analysis program.
- Designing pressure testing and fluid sampling programs to determine fluid densities, contacts and productivity from wireline test analysis.
- Designing bottom-hole and surface sampling procedures to obtain representative reservoir fluids.