Updating Our Lexicon

New stratigraphy lexicon puts Kingdom’s geology at our experts’ fingertips

This new lexicon has been designed in a way that makes it easy to update based on new data sets and can even handle future modifications.

New stratigraphy lexicon puts Kingdom’s geology at our experts’ fingertips

Fifty-five years after its inception, the Kingdom’s stratigraphic lexicon is getting a makeover.


Aramco’s Exploration admin area recently presented an updated stratigraphic lexicon to management, and more than 400 professionals and officially launched a new Lexicon Interface. 


The lexicon, which is the result of a multiyear project led by our Surface Geology Division, can be thought of as an in-depth geoscientific dictionary that defines, names, and describes all of the rock layers — what geologists call stratigraphic units — within the Arabian Peninsula.


Stratigraphy is an area of geoscience that explains the origin, composition, distribution, and succession of different rock layers (strata). Giving an official definition to the stratigraphy helps the company’s geoscientists and engineers communicate, making it easier for them to work together to find and get oil and gas out of the ground. 


Because hydrocarbons form in, migrate through, and are eventually trapped within these rock layers, defining stratigraphy is fundamental to successful oil and gas exploration and production. 


The road to mapping the Kingdom’s geology

Geology lies at the core of every oil and gas company, and none more so than at Aramco. In the first two decades of oil exploration (1930s-1950s), our early geologists started to describe, map, and name stratigraphic units at places where rock was exposed or “cropped out” at the surface (outcrops) throughout Saudi Arabia. They documented their findings in a series of technical reports, but there was no unified mapping strategy. 


In July 1953, James T. Duce, then vice president of Aramco, and William Wrather of the U.S. Geological Survey, with the support of the government of Saudi Arabia and the U.S. Embassy, came up with a project to systematically map all outcrops in the Kingdom. 


The mapping project was approved in 1955 by Fred Davies, chairman of the Aramco Board of Directors, and assigned to chief geologist Richard Bramkamp, and later, Leon Ramirez. The project resulted in the 1963 publication of the “Geologic Map of the Arabian Peninsula.” 


The first lexicon, the new lexicon

Building further on this work, Aramco geologist Richard Powers put together the first official stratigraphic lexicon of Saudi Arabia, which was published in 1968. This first lexicon brought together all of the key geological information documented by geologists that had worked in the Kingdom since the early 1930s, including famed Aramco geologist Max Steineke. 


However, since then, significant advances in geoscience and subsurface technology mean that the definitions of many of the 179 units in the original stratigraphic lexicon are now outdated, and also, Powers’ lexicon does not include the many stratigraphic units identified and defined since 1968. Fortunately, thanks to the collaborative efforts of our Surface Geology Division and geoscience experts throughout the company, we now have a new, updated stratigraphic lexicon. 


This new lexicon has been designed in a way that makes it easy to update based on new data sets and can even handle future modifications to the current stratigraphy. The new lexicon also has a web-based, interactive interface, where users can access information, tools, and downloadable images that can be used to help explain complex stratigraphic concepts. 


The new stratigraphic lexicon is now available through a web-based application, named the Lexicon Interface, entirely developed in-house by the Geographic Information System team in the Exploration Applications Services Department of the EXPEC Computer Center, which puts a wealth of critical geoscience information at the fingertips of our geologists, geophysicists, and engineers, and makes it easy for them to find what they need, no matter the stage they are at in their career or their area of expertise. 


In the new lexicon, 120 stratigraphic units are described for eastern and northwestern Saudi Arabia, and another 32 are described for the Red Sea Basin. In addition to summaries of Saudi Arabia’s stratigraphic units, users can dig in deeper for more details about each unit, such as the characteristics of the rocks, their tectonic evolution, their distribution, or the types of environments that they originally formed in, and so much more, all available through the new, web-based, user-friendly stratigraphic lexicon.


Caption for top photo: Words matter, especially when it comes to accurately describing the Kingdom’s geography. To help with this, Aramco has recently introduced a new stratigraphic lexicon that updates its original work published in 1968.


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