Exploring the Fundamentals of Applied Geophysics

Geophysical Survey Methods

• Reflection Seismic Method is based on the principles of seismology, utilizing seismic waves to image subsurface features.
• Depth of penetration for the Reflection Seismic Method can reach several kilometers, depending on the geological conditions.
• The geomagnetic survey method measures the local geomagnetic field to map subsurface structures and mineral deposits.
• Resistivity methods, once common in oil prospecting, are now increasingly employed in civil engineering for bedrock investigations.
• Electromagnetic survey methods provide information on subsurface rock bodies by analyzing their electrical conductivity.
• Gravimetry measures the gravitational field, relating variations to differences in rock densities, providing insight into subsurface composition.

Branches of Geophysics

• Geophysics examines the Earth’s physical properties through the application of physical sciences and various methods.
• The primary goal of applied or exploration geophysics is to locate and assess natural resources such as oil, gas, and minerals.
• Engineering geophysics specifically focuses on soil mechanics and developing plans for construction projects.

Environmental and Exploration Geophysics

• Environmental geophysics studies subsurface contamination and physical properties related to environmental impacts.
• The main method used in petroleum exploration is the Reflection Seismic Method, providing critical data for resource extraction.
• Exploration geophysics primarily aims at locating and evaluating natural resources, guiding resource management.

Historic Techniques and Developments

• Gravity measurement techniques assess the gravitational field to identify resource-rich geological formations.
• The first technique used in the Gulf Coast, USA to search for oil-bearing structures was the geological mapping of surface features.
• The reflection seismic method identified salt dome structures successfully in 1924, marking a significant breakthrough in geophysical exploration.
• The establishment of the reflection seismic method occurred in the 1930s, evolving through further advancements.
• The refraction seismic method was introduced in Iran in the 1950s, effectively recovering oil-bearing limestone structures.
• Extensive use of reflection seismic techniques began in the 1950s and 60s, transforming exploration practices.
• Malaysia introduced its first offshore seismic survey in the early 1970s, expanding exploration capabilities.
• The first 3D seismic survey over the Friendswood field near Houston, USA, was conducted in the early 1990s, enhancing data resolution for subsurface analysis.