The development of the shale oil industry in the USA has come about because of the use of new technologies such as hydraulic fracturing, otherwise known as fracking.
Fracking is a subject that has stirred a lot of debate, with environmental groups expressing concerns about the impact on the soil and ground water sources.
I am not going to get into that debate. But it seems to me that this video at least helps to explain what the process is actually about. The video has been produced by Marathon Oil, so of course it presents a rosy, environment-neutral outcome. Whether you agree that fracking is harmless or not is up to you, but the video is well made and gives a simple understanding of the process. It’s at a Geology 101 level, in other words it does not get too technical and does fail to answer a couple of questions, but it is worth a look.
Hat tip to Hardrock 48 for passing on the link.