Illinois Basin

Illinois Basin Overview

The Illinois Basin mainly covers parts of three states – Illinois, Indiana and Kentucky. Most oil production comes from geological formations less than 4000 feet in depth.

Oil was first discovered in Illinois in the late 1800′s near the town of Litchfield in west central Illinois about 50 miles Northeast of St. Louis. This was not a major discovery and the records are very sketchy to say the least.

It was not until 1906 when the Lawrence Field and the Main Field were discovered in Southeastern Illinois in Lawrence County and Crawford County that Illinois began to become a serious producer of petroleum. Production from these fields were from very shallow geological formations, most of these were sandstones. Conditions for capitalization were prime: The automobile had just been invented and would soon change the style of transportation in America and the rest of the world – therefore the demand factor was in place; factories and other elements of the Industrial Revolution had a need for oil; there was a need for heating oil in homes; oil production in other states such as Texas was just beginning (e.g. the Spindletop discovery well of the East Texas Field had just occurred in 1901).

As far as oil is concerned, things remained pretty much status quo until the late 1930′s when there was a series of new discovery wells that resulted in giant oil fields in Southern and Eastern Illinois. The primary pay zones in these fields were slightly deeper than those in the Lawrence and Main Fields. The new finds also often produced from geological formations of limestone. As mentioned above the earlier fields had almost always produced from various sandstone formations. The production from these new discoveries caused Illinois to reach its historical peak production in the early part of the 1940′s – it turned out to be a critical factor in supplying the Allies with fuel needed to win World War II…, Hitler did not have such a source of energy at his beck and call.

Illinois oil production has certain key advantages. First of all is the geological factor – its oil zones are extremely shallow. The shallow zone factor has a direct affect on the economic factor because drilling and developmental costs normally will be considerably less than the deeper wells of other oil producing states. Simply stated, Illinois wells are low cost. Another advantage is the product itself. The oil produced in Illinois is known in the industry as “sweet,” which denotes low sulfur content and is easy to sell. Plus, most of the oil produced is high gravity. The higher the gravity means a higher price when the crude is sold to the oil purchaser.

The Illinois Basin is now a mature basin with a low probability of discovering large oilfields. That is not to say that there isn’t good potential for new discoveries. Infill drilling to deeper untapped reservoirs is still very attractive and can be very profitable. In addition many of the existing fields have secondary production potential (primarily waterflooding).

Illinois Basin

Illinois Basin

 

Geologic Column

Geologic Column

 

Comments are closed.