May 7th, 2012
Marcellus Shale Marcellus shale, also known as Marcellus Formation, is a unit of marine sedimentary rock. Marcellus Shale is a Middle Devonian-age black, low density, and very organically rich shale. This black shale was deposited in relatively deep water with no oxygen. It can sometimes contain limestone beds, concentrations of iron pyrite and siderite. Marcellus shale was named by James Hall, 1839, after the village of Marcellus, New York. The location of Marcellus Shale extends across a lot of the Appalachian Basin of eastern North America. It stretches approximately 600 miles into states such as Ohio, West Virginia, Pennsylvania, and New York. Also in small parts of Maryland, Kentucky, Tennessee, and Virginia have some Marcellus Shale. Marcellus Shale has many untapped natural gas reserves that have very high demand in the markets along the East Coast of the United States. This makes Marcellus Shale a good target for energy development.
Marcellus Shale is an attractive target but also is an expensive target. This is because Marcellus shale is approximately a mile or so below the surface of the Earth. The way to get to the natural gas within the Marcellus shale would be to drill. The cost of drilling is ridiculously high, so wells must yield a great volume of natural gas to pay for the drilling costs. These drilling costs can be millions of dollars for a vertical well and a lot more for horizontal wells.
The drilling process is very complicated and it is a lot of work and money. There are two types of drilling wells; horizontal wells and vertical wells. Vertical well were drilled mostly in past years. They were just straight down and normally had much less natural gas production then horizontal. Horizontal wells unlike vertical uses tons of water (about 10% more), approximately four million gallons per well. These wells start out straight down then gradually curved until is it horizontal and is drilled that way. The reason they use horizontal drilling instead of vertical is because the joints in Marcellus Shale are vertical. So a vertical well would intersect a few joints but a horizontal well should intersect a large amount of joints.
In modern day drilling they use horizontal drilling with hydraulic fracturing. This is where the word “Fracking” comes from. Fracking is when you use water at high pressure to crack the shale’s formation to release methane gas. The pressure can range from 10,000 to 15,000 pounds per square inch. Also chemicals are added to the water for the “slick water” hydraulic fracturing. Hydraulic fracturing you seal off a portion of the well and inject the water so the portion of the well fractures the shale and pushes the fractures open. When the pressure is reduced some fractures close, so to prevent this they pump sand down the well and forced into the fractures and props the fractures open, which increase the flow of natural gas to the well.
There are two types of Natural Gas that are drilled out of the wells; Wet gas and Dry gas. Wet gas has a lot of liquid compounds, such as propane, ethane and butane. These gases have to go through a process before it can be sold. Most wet gas can be found in the western part of the Marcellus formation. Dry gas doesn’t contain the liquids found in wet gas and it is ready to be pipelined and sold.
Once gas is comes out of the ground it needs to be processed and sold. There has to be a pipeline from the drilling site to compressor stations and processing facilities then to the market where it will be sold. A compressor station moves the gas from one place to another and with the newest technology there are compressors that produce a total of about 17,000 horsepower. Processing facilities remove the liquid compounds from the wet gas so it can be sold.
There are many regulations to the entire Marcellus shale drilling process. MarcellusShale.us says that pipelines are handled by many different agencies.