This glossary contains pipeline-related terms and abbreviations that are used in this blog. Terms in bold are those for which you will find definitions. But first, here is a brief description of the processes involved in the Mariner East pipelines.
The beginning of the process is fracking, which releases the raw natural gas found in western Pennsylvania’s Marcellus shale formation. Near the source, the gas goes through a basic separation process called fractionation, which removes impurities and separates the consumer-ready dry gas from the natural gas liquids. The latter are piped at high pressure to the port at Marcus Hook, where they are loaded onto a fleet of Dragon ships and transported to Europe. There, at a cracking plant, they are converted into intermediary products for the plastics industry.
The pipeline is built using a combination of trenching and horizontal directional drilling. Drilling fluid is used to lubricate and power the drill. After a pilot hole has been drilled, it is expanded with an augur and pipe is pulled through in the pullback process.
Augur: a type of drill bit used to enlarge, or “ream”, a previously-drilled pilot hole. Also known as a “reaming tool”.
Bentonite: a type of clay which, in combination with water, is used to make drilling fluid.
Borehole: the hole made by drilling.
Drilling fluid: a mixture of Bentonite clay and mud. It is pumped down the drill string to lubricate the drill bit, and it returns back to the drilling site through the space along the outside of the drill string, carrying bits of rock and soil from the drilling. It is filtered and used again.
Drilling mud: industry term for drilling fluid.
Drill string: the combined length of drill-pipe sections, each of which is added as the preceding one disappears into the ground.
Frac-out: industry term for an “inadvertent release” of drilling fluid. The fluid follows a crack in the rocks to the surface, where it appears in an unintended location. The crack may be caused when the pressure of the drilling fluid causes the rock to “fracture”, hence the name “frac-out”.
Fracking or hydraulic fracturing: the process of injecting high-pressure liquid into a well or borehole to fracture the rocks, releasing trapped oil or gas. Fracking is the source of the natural gas liquids to be carried by Mariner East 2.
Horizontal directional drilling. A method of tunneling in an arc that descends underground from one location, then rises to the surface in another, so that a pipe can be pulled through the hole.
Pullback: the process of pulling a pipe through a previously drilled and reamed hole.
Chemical and gas-industry terms
Alkane: the chemical family that includes methane, ethane, propane, and butane, among others. These are distinguished by the number of carbon atoms in the backbone of the molecule. A mixture of alkanes is always found in the raw natural gas emerging from a well, but the proportions may vary.
Butane: a component of natural gas liquids. At room temperature and normal pressures, it is a gas. Its molecules contain four carbon atoms. It can be liquefied by being cooled or compressed. It is a member of the alkane chemical family.
Cracking: the industrial process of removing hydrogen atoms from alkanes to produce intermediary products used in the production of plastics and other materials. Cracking ethane, for example, results in ethylene, which is used to make polyethylene plastic. (Not to be confused with “fracking”, which is a drilling technique.)
Dragon Ships: a fleet of eight custom-built ships, chartered by the petrochemical firm Ineos, for transporting natural gas liquids from Pennsylvania to Europe.
Dry gas: Natural gas from which the natural gas liquids have been removed.
Ethane: a component of natural gas liquids. At room temperature and normal pressures, it is a gas. Its molecules contain two carbon atoms. It can be liquefied by being cooled or compressed. It is a member of the alkane chemical family.
Fractionation: the process of separating the various components of raw natural gas. It is done at plants in the vicinity of natural-gas wells, before the gas is shipped to market.
Propane: a component of natural gas liquids. At room temperature and normal pressures, it is a gas. Its molecules contain three carbon atoms. It can be liquefied by being cooled or compressed. It is a member of the alkane chemical family.
Natural gas liquids: Not actually “natural gas” nor “liquid” in the usual sense, this term is used for the gases ethane, butane, and propane, which are compressed into a liquid for storage, shipment, or pumping. The pressure in a natural gas liquids pipeline must be maintained at about 1500 psi in order for these products to remain in a liquid state.
Raw natural gas: the gas emerging from a gas well. The largest component is methane, but it will also contain ethane, butane, propane, water vapor, and some sulfur compounds as well as small amounts of other chemicals. Before it can be used, the components have to be separated via fractionation.
Wet natural gas: industry term for natural gas containing a high proportion of natural gas liquids. Once most of these have been removed, the result is dry gas, which is shipped to consumers.
ETP: Energy Transfer Partners. This is the company that recently acquired Sunoco Logistics, the originator of the Mariner East pipeline project.
DEP: the Pennsylvania Department of Environmental Protection. This is the state organization whose mission is to “protect Pennsylvania’s air, land and water from pollution and to provide for the health and safety of its citizens through a cleaner environment.” In the context of pipelines, it primarily issues permits for projects that cross waterways, lakes, and aquifers. The key concerns are pollution and erosion.
HDD: horizontal directional drilling. A method of tunneling in an arc that descends underground from one location, then rises to the surface in another, so that a pipe can be pulled through the hole.
ME1: Mariner East 1. This is the original Mariner East pipeline, which originated in 1930 and 1931 as a pipeline for transporting natural gas from Philadelphia-area ports to western Pennsylvania. It passed through various hands until Sunoco acquired it in 2002. Sunoco temporarily retired the pipeline in 2013, then put it back into service in 2014 as a pipeline carrying high-pressure NGLs from in the opposite direction, from fracking wells in western Pennsylvania to a shipping facility in Marcus Hook, south of Philadelphia.
ME2: Mariner East 2. This is a pair of new pipelines that Sunoco/ETP is currently building to carry additional NGLs from western Pennsylvania to Marcus Hook, for shipment to Europe. In this blog, I refer to it as the “Dragonpipe” because of the likelihood it will someday become a fire-breathing monster.
NGL: natural gas liquid. Not actually “natural gas” nor “liquid” in the usual sense, this term is used for the gases ethane, butane, and propane, which are compressed into a liquid for storage, shipment, or pumping. The pressure in an NGL pipeline must be maintained at about 1500 psi in order for these products to remain in a liquid state.
PHMSA: the Pipeline and Hazardous Materials Safety Administration. This division of the US Department of Transportation develops and enforces “regulations for the safe, reliable, and environmentally sound” operation of the US pipeline system (at least in principle).
PUC: the Pennsylvania Public Utility Commission. This governmental organization is tasked with regulating utilities on behalf of the citizens of Pennsylvania (at least in principle).