EGEE 101
Energy and the Environment

Extracting Oil and Gas

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 Equipment preparing to drill for oil. Details in caption.
After all the technology, there is still only one way of ensuring that there is crude oil or natural gas at a particular location, and that is to drill. We don't just drill holes! There has to be drilling mud to cool the bit, and a pipe so there is no contamination of the local water table. This image shows a bulldozer for building the road and bringing in equipment. The drilling rig with spare pipeline, concrete mixing, and well-logging trailer.
Credit: Dr. Bob Watson, PSU

There is only one way to tell if the location you have picked contains any oil or natural gas: drill! This is one of the most expensive parts of the extraction process and there is a lot of technology employed in selecting the location and technologies employed. In the "good old days" a wooden platform (a derrick) would have been built to enable the drilling process. Roads are often built to allow the machinery into the appropriate locations, machinery, equipment, and pipes that will be used at the site. Not to mention the storage of the crude (or natural gas) and the extraction and storage of the saltwater. The drill bit rotates and chew's into the earth. If you have seen Armageddon (Bruce Willis drilling into an asteroid) you know that drilling is both an art and a science. There is lots of friction and heat so it is necessary to cool the bit with drilling mud. In most cases, there will also be a need to enclose the circumference of the hole with pipe to stop it collapsing. As the hole gets deeper more casing is added. Eventually, there is a pipe going deep into the earth. Sensors attached to the drilling system alert the operators to when they reach the desired position and if there is any "black gold" (or natural gas or both). It is undesirable to let the oil burst out of the ground because you lose some of the reservoir pressure (that pushes the oil out of the ground). A production pipe is lowered and concrete poured to fill the gap between the production pipe and the enclosing "pipe".

Picture of a piece of stainless steel pipe with several holes in it.
(left) This stainless steel pipe is large but clearly shown are the many perforations created by a "bullet" shot from the inside out to allow the oil to flow into the pipe. (right) A close-up of the bullet hole.
Credit: JMP

Now we have a deep hole in the ground. To allow the reservoir (the oil-bearing rock) to make contact a perforation gun is used to "shoot" a hole through the production pipe. There are also techniques used to frac (short for fracture) the oil-containing rock so that production can increase the flow of oil out of the ground (recall lesson 4!). If there is associated natural gas with the oil then the oil will flow out of the ground. Unfortunately, in many of the PA wells and at other locations this does not last and the reservoir pressure drops and the remaining crude oil (that is extractable) has to be pumped out of the ground.

A labeled sketch of a horse head crude oil pump used to pump crude oil out of the ground.
Horse head pumps.
 

The horse head pumps pump the crude oil out of the ground. If you need more crude oil then drill another well, situate it close to an existing production well so you expect to find crude oil, and add another pump (horse head). In PA we have lots of these stripper wells (a well that does not produce more than 10 barrels of crude oil in a week). Being English I know these horse head pumps as "nodding donkeys".

Extraction and Production of the Crude Oil

Chemicals are added to the production pipe to try to prevent build up of deposits or wax. Remember the oil is warm and so cools on reaching the pipe. In winter or in waxy oils wax formation can plug a pipe and a pig (type of scraper) is sent down to clean the tubes. Even with good management we cannot produce large quantities of crude oil without drilling lots of wells. In PA there are about 100,000 wells that have been drilled for oil and natural gas (many now abandoned). Having said that there are locations in the world where a single well can produce 10,000s of barrels a day.

However, the quantity of crude oil coming out of the ground is a small percentage of what is in the reservoir. If we can increase our extraction efficiency resources that become reserves, our useful supply of crude oil will last longer. I like (industry) video (5 min long) for natural gas (oil extraction is very similar). Pay attention to the drilling and fracking (this is an example of a horizontal well) process. Look for good terminology to use in your exam answers!

Primary Production

The "natural lift" and "artificial lift" might produce 10 - 25% of the oil in the reservoir. To get any more, other techniques need to be used. Of course, these other methods include additional expenses. Many of the Middle East wells have natural lift that runs for very long periods. In the US most of our oil requires artificial lift techniques.

Secondary Production

The saltwater produced by the well or other water (such as municipal drinking water) can be pumped down into the reservoir. The oil, being less dense than the water, floats on top and is thus forced into the well bore of the production pipe. By utilizing water flooding, perhaps an additional 10% can be obtained.

Tertiary Production

Steam or chemicals are pumped down to lower the viscosity of the crude oil and to enhance the extraction process. Of particular interest for Lesson 12 is the use of CO2 as an enhanced oil production technique.

Oil is found in many locations around the world although the high-quality crudes are not as well dispersed. The Middle East now produces almost 30% of the World's crude oil supply.

Map of world's oil production by region (29% Middle East, 20% North America, 12% Eastern Europe, 11% Far East and Oceania, 10% Africa, 9% Central and South America, and 9% Western Europe).
Leading nations for oil production.
Credit: EIA
 Graph of Middle East production, Saudi Arabia is the largest.
The Middle East supplies over 1/4 of the world supply. The major producer in the region is, of course, Saudi Arabia. The production costs from the Middle East are a few dollars per barrel. Transportation adds to the cost as do taxes but the profit is still higher than the domestic crude. Purchasing that might have lower transportation costs but higher production costs.
Credit: EIA

Unfortunately, the US production of crude oil is starting to be reduced and this has implications. Click on the image to see why! We are becoming (again) increasingly dependent on imported crude oil. We are starting to look and drill for crude oil in deep water and environmentally sensitive areas. Domestic production is preferred over imports only when the costs are comparable. We take cheaper crude when we can get it. Wouldn't you?

But we also need to realize that the extraction part can go wrong and cause lots of environmental damage. Take a look at these BBC pictures of the Nigeria delta. Some of the oil companies have pulled out because of safety issues, and the locals stealing oil also produces some of the problems. However, it is an environmental disaster that needs to be cleaned up. Social issues are also very important here.

Extraction of the Natural Gas From Shale Gas

Chesapeake energy has a very good 6 min video that gives a good overview of natural gas drilling into shale (similar to oil drilling). Also look at the horizontal drilling and hydraulic fracturing below and "fracking" or the use of water under high pressure to fracture and stimulate the well. You don't need to know all the technical terms, just get the basics of how drilling, stimulation, and extraction occurs. These gas shales are an "unconventional resource" but provide over 10% of our natural gas production. The shale contains organic material (kerogen) that undergoes maturation and the formation of methane. Challenges here are access to large amounts of water for hydrofracking (fracking) and water cleanup (due to chemical additives and hydrocarbon contamination) while protecting the environment. Have the goal of being able to describe the process of drilling (including horizontal drilling) and fracking. Please note that this is for shale gas but also applicable for oil extraction.