Electric Power Consumption in South Texas – Growing Due to Eagle Ford Development

Power consumed by month- MW hours

In response to client inquiries, I've estimated the rate of growth for electric power consumption in the Eagle Ford area. The client is interested in pipelines running in close proximity to high-voltage AC power lines. By looking at the “Electric Reliability Council of Texas” (ERCOT) website and mining their data for counties in South Texas, here are some interesting facts:

1. For the South Texas region including Maverick, Zavala, Atascosa, Live Oak, Bee, Goliad and Refugio Counties, and all counties south of that line, electricity demand has grown at least five percent a year from 2008 through the end of 2011. The growth from 2010 to mid-2012 has been eight to ten percent a year;

2. The Rio Grande Valley’s general growth in population appears to be about two percent per year. Corpus Christi is growing at about one percent a year; Laredo is probably growing at three percent per year. These estimates come from what appear to be credible internet sources. So more generalized population growth in South Texas may be two percent a year, in the population centers mentioned above;

3. What this leaves, for explanation of recent growth rate, is the Eagle Ford Shale development – which affects all of the counties along the northerly line of this “South Texas” geography, and many more counties southward. And it’s just the southwest half of the Eagle Ford that gets described – I did not gather data on Wilson, Karnes, DeWitt, Gonzales and other prolific Eagle Ford counties to the northeast.

Power Lines Carry More Power to Supply the Growing Population

Just as important is how much of this new electric consumption is focused on a dozen or so counties and maybe 20 cities. For instance, the city of Carrizo Springs, in Dimmit County, has probably grown, in terms of “overnighting” residents, from about 6,000 to more than 30,000 people between 2009 and the present. This means that high-voltage AC power lines into the Carrizo Springs area are carrying more than five times the average power than in earlier times. And that accounts only for the typical residential and light commercial usage. What additional electric loads have been added for major new businesses, industrial processes, large motors and pumps on new water wells, new salt water disposal well operations, and so on?

The infrastructure build-out to support this Eagle Ford Shale boom is much broader, and more complex, than any one business person or engineer can grasp. We hope that the water and sewer utilities, the electric power generation and distribution companies, the state and county road authorities, and the telephone and data carriers are all focused closely on this growth. The growth has been clearly described, too, as having at least two phases. There is the heavy surface access, drilling, midstream and other infrastructure development time, which probably will extend another five to seven years out in front of us. Then there is the long-term production – “lift and move oil, condensate and gas” operations, maintenance and repairs – time-frame, which used to look like 10 to 20 years from the present, and now looks like 25 to 35 years. We can call this development and production work sustainable for at least 25 years, and possibly much farther out into the future.

Planning is Essential in Avoiding Shortfalls

Unless all these entities are planning and investing in ongoing and smart fashion, there are going to be periodic and painful shortfalls, bottle-necks, and logistical snarls . . . Cooperative planning, good communications, and visionary people are needed across the landscape – in private business, in the affected city, county and state offices, in the politicians’ meeting spaces, and in civic organizations. A lot of common good stands to be achieved, for many, many South Texas communities. I believe in market forces to allocate resources and labor and work effort. But such”infrastructure” things as roads, and electricity, and water and sewer utilities don’t grow well unless there is good planning and communication, and cooperation between public and private entities.

And back to the high-voltage power lines: as they also grow in capacity and reach, they may represent substantial corrosion risks to adjacent pipelines – a problem Chapman Engineering has described in an earlier blog piece - “AC-Induced Corrosion on Pipelines in the Eagle Ford Shale.”

AC-Induced Corrosion on Pipelines in the Eagle Ford Shale

New pipeline construction is going “fast and furious” in the Eagle Ford Shale region, in the West Texas “Wolfcamp”, “Bone Spring” and related shales, and all across mid-America with the Bakken, Niobrara and other successful unconventional oil and gas plays.  Companies who build and operate pipelines must attract customers with product to move, secure the land over which pipeline right-of-ways will be cobbled together, and then construct the pipelines.

What happens when a pipeline runs near a high-voltage AC power line?

When soil resistivity is lower, and the voltage driving current along the AC power lines is high enough, the pipeline acts like the “secondary winding” of a transformer.  It receives AC power from the high-voltage lines by what is called “electrical induction.”  Once that power builds on the pipeline, AC electric current flow is going to happen.  When that AC current finds a place to “jump off” the pipeline to go back to the AC power grid, corrosion holes are created in the pipeline metal.  This is AC-induced corrosion, and it is a severe threat to pipeline integrity.

This induced AC power may even pose safety risks to the welders, laborers, operators and other people building the pipeline!  AC power can actually build up on the pipe as it sits above grade on cribbing.  Any time a pipeline is located in “near parallel” to parallel arrangement with high-voltage AC power lines, even for just a mile or two, a qualified corrosion engineering consultant should be brought in to check the situation.

Risks of AC-induced Corrosion and Voltage Buildups

These risks for AC-induced corrosion and unsafe voltage buildups are significant.  A recent story about a Barnett Shale area worker, directed to do some repair to a chemical injection system for a pipeline’s internal corrosion control system, tells the tale.  The gentleman walked up to a chemical injection point and reached up to close a small ball valve, before changing out some injection equipment.  The AC voltage buildup on this pipeline was so great that, when he touched the valve handle, he was hurled backwards by the jolt of “grounding out” the induced AC power!  From what was passed on, he did not suffer lasting injuries.  But this was way more than 15 volts of induced AC (the maximum “safety” voltage threshold), and a significant current passed through part of his body for the instant he was in contact with both the pipe and the earth.

AC Mitigation Systems Might Be Needed

If the opportunity for AC power buildup on the pipeline is pronounced, then "AC mitigation" systems must be designed and installed.  Similar to electrical grounding and lightning protection approaches, these mitigation systems are specialized in design, construction and monitoring.  Recognizing the need for them is paramount, especially when soil resistivities are low and chemical ions such as chlorides are present in higher concentrations in soils.  A lot of the soils in the Eagle Ford Shale play have this “not good” combination of resistivity and soil chemistry factors.  The same can be said, too, for a lot of West Texas and southeastern New Mexico.

Corrosion Control in the Eagle Ford Shale

Corrosion control is always a factor in oilfield work.  Above-ground tanks, pipelines, and all manners of equipment suffer from corrosion, both internal and external in nature.  The farther south and west one moves across the Eagle Ford play, the more two interesting physical facts come to dominate external corrosion control needs. Maverick, Dimmit, Zavala, Webb, La Salle, McMullen, Frio, Atascosa, Live Oak and Bee Counties have shallow soils which often contain large concentrations of chloride ion.  This comes from salt deposited when ancient ocean shorelines ranged across the region.  High chloride ion content causes aggressive corrosion rates on unprotected steel.  Just as importantly, the sodium and chloride ions, often found with other ions as well, cause the soil’s electrical resistivity to be very low.  The low electrical resistance means high corrosion current flows, which again accelerates attack on unprotected steel.  Pipelines are buried in this soil.  Tanks are set on it.

Even in the other counties in the play, external corrosion is a big factor.  Those soils are often clayey loams with varying amounts of gypsum and other water-soluble minerals.  So corrosion potential is high, no matter where you’re working.

Best Practices for Corrosion Control

Corrosion protection for these facilities should always include a combination of good coatings, good installation and inspection practices, and well-designed cathodic protection (CP) systems.  Here are some pointers for the southwesterly “half” of the Eagle Ford:

• If constructing bulk above-ground storage tanks (ASTs), put a coating on the bottom plate before field welding begins.  This coating will give partial protection to the finished external bottom of tank.  This reduces the amount of protective electrical current needed.  It lowers capital costs for the CP system, AND can greatly reduce a monthly electric bill;
• If high-voltage AC power lines are nearby, avoid setting up pipeline rights-of-way in “close parallel” to the AC lines!  With the low soil resistivities, high chloride levels, and good coatings, the AC-induced corrosion rates are EXTREMELY HIGH!  (An article about this risk will come soon.)
• Holiday detection is even more important for coatings inspection on pipelines, tanks, and, really, on any paint job where the metal will be in soil or water contact.  Remember, too, that water gets everywhere, sooner or later;
• Coat the bottom of every steel vessel before it is set – not just a paint, but a better-quality and thicker coating!  Dehydrator units, separators, bulk tanks all may be set on crushed rock or caliche, but the chloride ion will move to the metal – just by diffusion – and attack it over time.

These observations and recommendations are based on experience, not on “ivory tower” theorizing.

Basics of Corrosion Science

For those not so familiar with corrosion science, here are a few points to keep in mind:

1. If we just talk about steel, it is not a “naturally occurring” material.  Iron ore is dug up, then combined in very hot furnaces with coke and other alloying metals.  The resulting steel is then cooled, shaped, and so on;
2. A lot of new energy is added in the metal-making process.  As soon as this metal is put into the environment, Mother Nature’s electrochemical processes go to work.  Their goal is to turn steel back into iron ore – rust!  The reason?  All that energy put into the making of steel is now available to be removed.  One physical law is that everything, sooner or later, will be “taken back” to its lowest stable energy content;
3. To prevent or slow down that rusting process, every piece of steel should be coated, maybe even inside as well as outside.  No water, either liquid or vapor, should be allowed to contact it.  Water is the major "rusting agent" around, even if just a vapor or a dewfall.  And there are plenty of other chemicals which may drive the corrosion process, chloride ion being one;
4. Finally, in addition to the coatings, cathodic protection should be applied.  Coatings by themselves are not good enough, because there are always defects or holes in them.  And the cathodic protection should be sized to give protection for as many years as you want the structure to do its job.

Mr. Chapman is one of many professionals who will be contributing to EagleFordShale.com. If you have professional experience in the Eagle Ford and would like to be considered as a contributor, please Contact Us about guest blogging.