June 10, 2009

Hiring a Geologist is a Waste of Taxpayer Dollars

By Alden Nellis

Note: Alden Nellis majored in Geology at SMU in the early 1960s and worked in the “oil patch” as an analyst and researcher for ten years in the late 60’s and early 70’s.

How do you get to the bottom of any problem? The Cleburne City Council, like most government entities, reacts to a problem by spending (read that wasting) taxpayer dollars. Hiring a geologist to do a study on why we have had recent earthquakes is a farce. Does someone at City Hall have a relative who is an unemployed geologist and could use some quick cash?

Yes, it would be interesting and educational to know why we now have earthquakes in Cleburne . But that is an academic pursuit and no amount of study is going to change the fact that we are suddenly having earthquakes nor the fact that they could stop as quickly as they started – or not.

If something has been the same for a long time, like no earthquakes in the history of Cleburne , then suddenly changes, the first question to ask is “What is different?” What has changed in this case is gas and oil production from the Barnett Shale. Naturally the oil and gas companies are in denial because of our over-lawyered, sue-happy society.

Let us look at the geology and physics of the Barnett Shale activity. The Barnett Shale is a dense, hard, brittle rock with large quantities of gas and a little oil trapped in it. If a conventional well is drilled down to the shale, only the pockets of gas that are ruptured by the drilling will be produced. Many years ago the “oil patch” developed a process called fracing (pronounced fracking) where they fractured the oil/gas bearing rock around the well to induce greater production.

Recent technology allows them to drill a well down to the formation, then drill horizontally through the formation for as much as a mile, thus allowing one well to replace a mile-long string of wells spaced every few hundred feet. Now, fracing the mile-long horizontal adds a whole new dimension to production.

Fracing is accomplished by drilling a well with the horizontal leg, then pumping that full of millions of gallons of water under very high pressure. While the rock is stressed by this pressure, and charges are detonated along the horizontal, effectively acting as a series of hydraulic hammers. As a result, the rock formation (Barnett Shale) is shattered and the oil/gas is freed to flow out of the well. With the spider web of thousands of wells, virtually the whole field can be brought into production to produce billions of cubic feet of gas.

Two changes have taken place in the Barnett Shale. Essentially this whole formation of dense, strong rock has been shattered by fracing. And billions of cubic feet of gas have been removed, leaving billions of cubic feet of empty space throughout the now weak, shattered formation.

The earth is a dynamic, fluid system of layers and masses of rock. When one layer is damaged, like the Barnett Shale in this case, the rock will flow up or down to fill the void. The gas/oil people would have us believe that Barnett Shale activity could not be contributing to the earthquakes because the earthquakes are much deeper than the shale. They would have us believe the rock above the shale would settle into the void in the shale. That is one possibility.

Another possibility is that the superstructure above the shale is much stronger than the substructure below it. In this case the weak rock will flow up to fill the void in the shale instead of the harder rock sinking down to fill the void. As it does, it will relieve the stress on deeper layers and they will break – and that is an earthquake.

If the break occurs in softer, more pliable rock that does not build up a lot of stress before breaking, the quake will be mild, like those we have had. Cleburne sits on top of alternate layers of dense hard rock and soft pliable rock, primarily limestones.

If the break occurs in harder, more rigid rock, the quake will be more severe, like those they have in California .

SMU in Dallas has sent a crew to Cleburne with ten portable seismographs to measure and study future quakes. It will be very interesting and exciting to see the results of this study.

Meanwhile, we do not need to waste taxpayer money on our own study of something we have no control over and can do nothing about.