That we are using new and expensive technology to remove oil and gas from the source rocks is proof that the low hanging fruit of easy oil is gone. We have to climb higher and higher into the tree to get what we need, on longer and more expensive ladders.

Many of the areas that are reporting methane in their water wells have historically had problems with just this problem. Their bedrock is source rock, after all, and some of those hydrocarbons, especially the gasses, have been migrating up fractures and faults for a long time. Fracking has the potential of exaserbating the situation, but the actually study of this has been wanting. Better surveys of hydrocarbons in water wells before fracking commences would be quite helpful.

Regions that are experiencing a boom in employment due to new drilling must remember what every resource geologist knows: booms are followed by busts. Over-building infrastructure and expecting the boom to go on for a long time is a recipe for disaster down the road. Towns should not go into long term debt during the frenzy.

Companies should release fracking formulas so that wells can be monitored for these chemicals but I’m not holding my breath. Colorado is preposing such a law, but by the time it passed and clears the courts, it will be too late for the already affected groundwater.

We need the hydrocarbons but I fear that we may do more long term damage for short term gain. I’ve said it before on this forum and I’ll say it again: our thirst and hunger for earth resources knows no limits. We’ll drill and mine it all, no corner of the earth is safe for long if what we want lies under its surface.

All of this is easy oil. We’ve lived on this for a century now, and petroleum geologist and engineers are damn good at getting every drop they can.

they are so good at finding and exploitng these types of deposits that there are not many left. those that remain are in ecologically protected areas, and they are still limited compared to the amount we’ve tapped.

Which brings us to fracking. Fracking is a way of drilling very long wells that run horizontally through the rock strata, then the well is prussurized with fluids to fracture the surrounding rock to create pathways for the oil and cas to migrate towads the drill hole so that it can be recovered.

But here is the difference from the classic, simple oil reservoir. We are no getting the oil and gas from the Source Rock, the shales that, given time would have yield their hydrocarbon to the process I discussed above. The shales are “tight”. If we just sank a drill hole into them they would produce very little. there are no conduits for the oil to flow through to the well. So fracking creates the fractues to allow the hydrocarbons to be pumped out.

The advantage is that we are not waiting for Ma Nature to go through the long process of moving that oil to nice porus rock units, we are getting it directly from the source rocks.

However, the process is expensive, require an enormous amount of water (millions of gallons), and the wells really don’t last all that long. In addition, in order to create the high pressures to fracture the shale, all kinds of things are added to the water to increase to effective pressure. What chemicals you ask? Well, that’s the thing. Each company has its own propritary mixture, and they are pretty tight lipped about what they are shoving down the wells.

The process also requires a whole lot of sand. The sand is injected into the cracks to keep them from closing up and provide a nice permiable path for the oil and gas. In fact, there is such a huge demand for just the right kind of sand that quarrys are opening all over the place to supply the drillers with what they need.

And yes, injecting fluids under pressure can create earthquakes. This has been known wince the 1960′s when the military was disposing oil nerve gas bay pushing it down deep wells north of Denver, which experienced temblors of around 6.0 in magnitude. Now the fluids don’t lubricate exisitng faults, but they reduce the pressure needed to allow the fault to fail.

…conclusion to follow…probably tommorrow…

I thought I’d provide you with some basic understanding of petroleum geology prior to getting into fracking.

There are four major components to the classic oil reservoir:

Source Rock
Fluid pathway
Resevoir rock
Trap

First of all, we need a source rock. Despite common knowledge, it is not dinosaurs remains, but all the microscopic goo that is created in a marine setting – plankton, algae, and fish shit. Back in the day, many millions of years ago, there were fairly shallow seas that were spread out over the continents. they were teaming with life, whose remains and what not settled to the seafloor creating an organic rich shale, a few centimeters a year, for millions of years, creating deposits thousands of feet thick. How is it possible that a shallow sea creates deposits thousands of feet thick? Well, the sediments, as the they thicken, push the crust downward, allowing the deposits to grow thicker and thicker. Eventually, as the the seas receeded and the land lifted due to plate tectonics (called a regression), the mud was buried under new sediments shed by the erosion of the new mountains. Mud was followed by silt, silt by sand, limestone coral reefs, then sand, and coarser gravels as the seas gave way to more terrestiral sediments. As the mud was buried deeper and deeper, the pressures and temperatures increased, and all that organic material began to change to new things, like kerogen, a waxy material that is the precursor to petroleum. Eventually, the kerogen was distilled into all kinds of hydrocarbons – tar, oil, and natural gas.

But shales (what becomes of mud after this process) in not very porous (the spaces between the tiny little mud grains is very small) nor permiable (few pathways between those grains for fluids to move). However, given the high pressure, and that these hydrocarbons get squeezed out of the source rock, and a whole lotta time, they start to move.

These fluids will find pathways within the strata to escape – faults and joints and cracks that are created when the rock is buried and when the rock is pushed by plate tectonics into folds – like pushing a carpet from one end.

As the fluid move upward, they’ll find another rock unit, like a sandstone, that has lots of space between the grains for fluids to inhabit. Picture a sponge full of small holes that can fill with all of this hydrocarbon fluid. This is the reservoir rock. A rock with lots of interconnected holes that contain the oil, water, and natural gas.

Now unless there is another impermemiable layer above that reservoir rock, or that layer is cracked, the fluids will just keep on travelling upward until it reaches the surface; where it will pool on the ground as an oil seep.

However, it there is a shale unit above the reservoir, that upward migration is kept in check, creating a trap. These are often in folds of rock known as anticlines. Picture that folded carpet again and see how half of the folds create a ridge. If the hydrocarbons can collect in one of those ridges, and there is a good seal above them, then that pool of hydrocarbons just sits there, seperating out into layers of water, natural gas, and oil, getting more and mor mature and pressurized as time goes by. The great Texas oil fields are a good example. they were under so much pressure they’d blow out the rig when drilled into – a gusher!

So when you picture an oil field, don’t think of a big open cavern full of oil in the ground, picture a rock that’t like a sponge under pressure.

…more later…

Here.

Complete links at end of article.