Subsidence is the downward displacement of the Earth’s surface relative to a fixed datum.
Subsidence has been building up in my backlog of important Barnett Shale blogging topics that I can’t get to because all hell breaks loose daily. You see, when you take something out of something, it leaves an empty space and sometimes–think about a balloon filled with air or water–the something that the something was in collapses. Now think about your home sitting on top of the Barnett Shale. Got the picture?
From Geology.com
Mineral Rights
Basic information about mineral, surface, oil and gas rights.
The consequences of mineral extraction will be passed on to heirs and all subsequent owners of the property. It is not uncommon for undermined properties to show no signs of subsidence for decades after mining is completed. Then, cracks and settlement begin to appear. In this situation the mining company may be long defunct and its owners long dead. There is no one to hold responsible – even if repair of any damage was written into the lease or sales agreement.
Of course, industry will say that drilling for natural gas does not cause subsidence. Watch how they word things. The drilling won’t cause the subsidence but the EXTRACTION can and that includes the extraction of the staggering amounts of water used in natural gas extraction.
Man-Made Causes of SubsidenceMost man-made subsidence results from ground water withdrawal but the earliest observation of subsidence resulting from human activity was from oil and gas field production. The Houston, Texas area has perhaps the best examples in the world of subsidence that results from both ground water and petroleum withdrawal.
The first documented instance of land subsidence due to fluid withdrawal was from the Goose Creek oil field near the city of Houston. In 1917 oil was discovered on the margin of Galveston Bay near the mouth of the present-day Houston Ship Channel. After production of several million barrels of oil, bay waters began to inundate the oil field.
The subsidence also works the other way sometimes in the case of injection wells where they are injecting high volumes of water into formations. In that case, your house might rise up some.
Something weird is happening in the Arkansas gas-patch. UPDATE: they now have a video up.
Newer Dream Lake Home on Greer’s Ferry Lake Collapses! Neighbors believe intense fracking in area has put their neighborhood at RISK!
I’ve heard rumors that some houses in Denton havelready sunk but I haven’t had time to track those down because I only work part-time on drilling issues. Help me help you.
About Sharon Wilson
Sharon Wilson is considered a leading citizen expert on the impacts of shale oil and gas extraction. She is the go-to person whether it’s top EPA officials from D.C., national and international news networks, or residents facing the shock of eminent domain and the devastating environmental effects of natural gas development in their backyards.
- Web |
- More Posts(5121)
I used to catch up and ride mountain bikes with a retired geologist from North Texas University. Several years ago, I asked him what would happen to the topography of the Earth with the extraction of natural gas. His response is exactly as one would suspect and that you are pointing out: The Earth WILL settle. There is no saying when. We joked at that time, had a laugh, and I said something like this, "That will make mountain biking more interesting." HAHAHA. Not funny one bit, when you are talking about the foundation of your house. It doesn't take a rocket scientist, or an economist turned air specialist to figure out, the Earth is going to settle, concrete is going to crack. And it scares the hell out of me, especially over at 635/121/114 interchange. That's where Chesapeake has one of the largest areas of Natural Gas Extraction around. I just pray I'm not on that freeway interchange when it cracks and something like the bridge in MN happens.
Ahhh, the intersection of factoids and scientific illiteracy: “your house might rise up some”…
Subsidence happens because liquids can’t be compressed (it’s true: you can look it up). Therefore, pore spaces filled with liquids maintain their volume even when the rock that contains them is subjected to the pressure caused by the weight above them (about 1 psi for every foot of depth). Withdraw the fluids by pumping them out, and the rock bodies can now compress, thereby reducing their overall thickness slightly – that’s subsidence.
In order for “your house [to] rise some,” then, fluids pumped into a subsurface reservoir must exert an upward pressure in excess of the lithostatic pressure (the pressure due to the mass of the overlying rocks). Given a disposal well at, for example, 8000 feet deep; the fluids pumped into the reservoir must exert an upward pressure of at least 8001 psi. But that’s not enough, either, because rock layers aren’t particularly elastic, so the pressure must exceed lithostatic *plus* the pressure necessary to bend the overlying rock layers.
Of course in order to exert that sort of upward pressure, the fluids must be confined in all other directions by come container capable of withstanding whatever pressure is necessary to push several billion tons of rock (and your house) upward “some.” Oh, and last but not least, you also need a pump capable of shoving fluids into a subsurface reservoir at those pressures.
Ain’t gonna happen…
Ah, the intersection between know-it-all and dumbass. Uplift or heave from injection has happened and will continue to happen. There are a number of peer reviewed papers that address it and news stories about places where it has happened.
Ad hominem attacks are apparently the last refuge of the ill-informed.
The best-described case of oil-field subsidence in the WORLD is not in Houston, it’s Wilmington Oil Field, which underlies Long Beach, CA – first described in 1940 or so. By restricting the outflow and mandating that equivalent amounts of water be pumped back into the subsurface, the City of Long Beach (which is the operator and regulatory body in charge of the field) halted subsidence by 1958, Attempts to repressurize the reservoir to reverse subsidence met with limited success (a couple of millimeters). That’s against a maximum subsidence of 9m (29.5 feet, mas o menos). Observations like those at Wilmington and Goose Creek are one reason that regulatory bodies mandate maximum “allowable” extraction values in many oil fields and require operators to maintain a minimum reservoir pressure through waterflooding.
Here: educate yourself http://www.slb.com/~/media/Files/resources/oilfield_review/ors06/aut06/compaction_and_subsidence.pdf
People who conflate scientific fact with scare tactics do immeasurable damage to their causes. There is nothing those you hold in such low esteem like better than a chance to paint their detractors as unschooled.
What arrogance! No wonder opposition to fracking is increasing daily as more and more cities ban it.
But thanks for admitting that subsidence is a real problem in oil and gas extraction. And thanks for that best example in the WORLD. I’m confident that there will soon be another best example. Our regulatory agencies fail us on a regular basis and have been doing so for years.
By the way: “heave” is not uplift – “heave” is a geologic term that describes the vertical displacement on a fault. Plus, you’re conflating fracking with water injection. You really need to find someone to explain these things to you.
Fracking is injection. There are many kinds of injection.