Significance and Application of Core Logging in Geology

For over a century, geologists have been utilizing core logging to unearth the mysteries that lie beneath the Earth's surface. These logs, which can span up to an impressive 30 meters, have revolutionized our understanding of the planet's subsurface. From determining reservoir conditions to identifying complex underground formations and analyzing groundwater levels, core logging remains an indispensable tool in the geologist's arsenal. In this article, we will delve deep into the world of core logging, discussing its methods, applications, and paramount importance.

Figure 1.0 ( Coal Core drilled from Bank watch)

1. What Is Core Logging?

Core logs are drilled throughout the Earth's crust to measure geological formations and identify reservoir conditions. They provide valuable information about rock layers in a reservoir.

The term "core logging" is used for the act of measuring the thickness of exposed rock layers, measuring the porosity of exposed rock layers, and determining what types of minerals are exposed in an exposed section of rock. Core logging also measures water content, density, and permeability.

Core logs are usually drilled from borehole locations because they can be 30 meters in length. This allows geologists to gather a lot more data than they could with a regular drill hole.

Geologists use core logs in order to study how oil and gas reservoirs behave over time due to changes in pressures caused by declining oil production rates or other factors. Geologists also use core logs when drilling exploratory wells to create a detailed profile of underground conditions below the Earth's surface.

Figure 2.0 (Baltimore district drill rig operator)

2. Where Can Core Logs Be Used?

Core logs are used in a variety of circumstances. Geologists may use them to identify underground formations in Earth's crust or their composition in a reservoir. They can also be a very valuable information tool when studying groundwater levels and the conditions of a reservoir.

Geologists often use core samples in conjunction with other methods to study reservoirs and explore potential sites for drilling wells. Core logs help geologists measure the depth of the Earth's surface and determine how far below that surface they can drill without violating any natural hazards, such as oil-filled reservoirs, gas fields, fault lines, or earthquake zones. They're also an essential part of any geologist's toolkit.

In order to better understand what kind of rocks you're looking at, geologists will extract samples from cores and examine them under a microscope. This is a process known as petrographic analysis.

Figure 3.0( Thin section of gabbro from Rum Scotland)

3. How Can Core Logs Be Used?

Geologists use core logs to measure the depth of a borehole and identify different rock layers. They also have a lot of uses in the geology community. In addition to simply providing information on the depth of a borehole, core logs can be used for stratigraphic analysis and reservoir characterization.

This means that they provide an accurate representation of what's below ground level. This is especially helpful for those working in seismology, groundwater exploration, and petroleum exploration. Core logging is a large part of the geologist's arsenal and is essential for any project they're working on.

A good way to understand how important core logs are in the field is to see what happens when they're not around. One study found that without core logs, geologists were able to drill only about 100 meters deep before hitting bedrock instead of up to 30 meters deep without them.

Figure 4.0 (lithology and core logging)

When Should You Use Core Logging?

Core logs are used to determine the composition of rock layers in a reservoir, examine groundwater levels, and measure reservoir conditions.

Ground Water Level Measurements

Geologists use core logs to measure how high or low the water level is in an area. They can examine this information to help predict future flooding events or help identify newly discovered water sources.

What's more, geologists can combine measurements taken from different boreholes to map out groundwater levels across an entire region. This can be very helpful for understanding climate change over time.

Rock Layer Composition

The rock layer composition at the bottom of a borehole provides important information about what type of fossils and minerals might be found higher up in the Earth's crust. For example, if you drill deep enough into the Earth's crust, you may find coal deposits or oil reservoirs like those found in Saudi Arabia and Texas. Geologists use core logging to study these types of things.

Reservoir Conditions

Geologists also use core logging to monitor a reservoir's condition over time by taking samples at different depths each year for comparison. When they take these samples, they'll note any changes that have occurred over time with their observations and write all their findings down on

Where to Find More Information on Core Logging?

If you're interested in learning more about core logging, there are many sources you can turn to for example check out Core logging 101 from

Geologists use core samples to learn about the composition of underground formations and understand how they interact with the surface. They can also study geological events like earthquakes, volcanic eruptions, and landslides.

Core logs are used for a variety of purposes like determining groundwater levels, identifying subsurface structures, and measuring reservoir conditions.


Core logs are vital to geology. They tell geologists what is under the Earth's surface. The information they provide can be used in a number of ways, including measuring ground water levels and identifying underground formations.

A geologist can look at core logs to determine all sorts of things about the Earth's crust, like the composition of rock layers, the type of material in an underground formation, or how much oil is in a particular reservoir.

Core logging is one of the most important aspects to geology, and it has been around for over 100 years!

Post a Comment