Crude Oil, Separators, Pipelines, Cathode Protection System, Pump Stations, Tank Farms, Refineries, Distribution Centers and Gas Stations

Posted by PITHOCRATES - September 26th, 2012

Technology 101

Pipelines Crisscross the Country carrying Raw Crude Oil to Refineries and Refined Petroleum Products Out

Do you know what the most fascinating thing about the gasoline you burn in your car?  Only a few weeks earlier it was raw crude oil in the pores of rock deep underground.  The oil business is a remarkably efficient business.  Remarkable machines, pipelines and refineries have made getting gasoline into our cars a fast and speedy process.  But it hasn’t come cheap.  Those machines, pipelines and refineries are incredibly expensive.  Which is a power incentive to move and process that crude oil quickly.  From oil underground to gasoline in you gas tank.

And that process begins at the wellhead.  Because what comes out of that well is not pure crude oil.  What comes up the well is a frothy mixture of oil, gas and salt water.  They have separators located at or near the wellheads to separate this mixture into its components.  Getting the gas out of the oil is easier than getting the water out.  This often requires additional processing.  They can ‘dry’ the oil by cooking the water out.  Heating the oil (by burning some of the previously separated gas) in a container sends the oil to the top where it floats on the water.  The water pulled out of the well and separated from the oil is not clean enough to pour into a river or stream.  So they pump it back from whence it came.  Into another well.  Where it can help force more oil up to the surface.

They pipe the oil mixture from the wells in an oil field to these separators.  Pipelines from the separators carry the processed oil (and natural gas) to pipeline terminals.  Where they feed into a main pipeline that carries the oil to a refinery.  (Natural gas does not need refining and simply enters the pipeline system that distributes natural gas to end users).  Pipelines crisscross the country carrying raw crude oil to refineries.  And refined petroleum products out.  Sending jet fuel to airports.  Diesel fuel to railroad fueling yards.  And gasoline and diesel to the distribution centers that feed our local gas stations.

The Trans-Alaska Pipeline holds about 9 Million Barrels of Oil inside the Pipeline at any Given Time

There is a lot of political opposition to pipelines.  They say they are an environmental disaster waiting to happen.  In truth there have been few pipeline disasters.  For two reasons.  It takes an enormous investment to get oil out of the ground.  So any leaks in a pipeline would greatly reduce the return on their investment.  Secondly, oil is flammable.  Any pipeline leak could light the fuse to a powerful explosion.  Which would reduce their return on investment far more than just a leak.  So they make these pipelines out of high-strength steel with welded joints.  They even x-ray the welds to detect any defects.  Because any lost oil is lost profit.  Which means any accident that hurts the environment will hurt them in the pocketbook.  So they will protect the environment because that is the best way to protect their investment.

Steel corrodes.  Especially when in contact with the earth.  In fact, the chemical interaction of the elements in the soil with the steel in the pipeline acts like a battery.  Creating small electric currents that can accelerate the corrosion process.  So they cover these steel pipelines in layers of tar-like material and an insulation wrapping.  In addition to this they install a cathode protection system.  Where another more corrosive material is placed in contact with the pipeline so it corrodes instead of the pipeline.  Or they install an active system where they bury anodes underground along the pipeline and attach a DC power source.  They connect the positive terminal of the power source to the anode system.  And the negative terminal to the pipeline (the cathode).  This current can prevent the galvanic action that can accelerate the corrosive process.

Oil is thick and viscous.  It doesn’t flow easily.  So they need big (diameter) pipelines.  And lots of pumps to push this oil to a refinery.  Even under high pressures this oil moves leisurely along at about 3-5 miles per hour.  But it doesn’t have to move fast.  Not once we fill these pipelines with oil.  Because new oil pumped into the pipeline at one end pushes out oil at the other end.  And when it does it pushes out a lot of oil.  In fact, our pipelines hold far more oil than all our storage tanks at all our refineries.  The pipeline that crosses Alaska (the Trans-Alaska Pipeline) is about 4 feet in diameter and 800 miles long.  If you do the math that comes to about 9 million barrels of oil inside the pipeline at any given time.  By comparison a modern large oil tanker can carry up to 2 million barrels of oil.

We burn Gasoline in our Cars that mere Weeks Earlier was still Underground in the Porous Matrix of Rock Formations

There are pump stations about every 60-100 miles along a pipeline.  These pumps suck a lot of energy to pump that viscous fluid.  But it is still more cost efficient than shipping that oil by truck or rail.  These pumps usually have a roof over them.  But no walls.  To prevent any buildup of explosive vapors from accumulating.  Which is one of the drawbacks of dealing with petroleum oil and its products.  Especially the stuff we eventually pump into our gas tanks.

At pipeline terminals, refineries and tanker ports there is a backup of oil waiting to enter a pipeline.  Or to be refined.  So we have to store it.  In tank farms.  Where tidy rows of squat round tanks with floating roofs (to prevent any buildup of explosive vapors) hold enormous amounts of oil until the next stage in the oil processing system is ready for it.  But not for long.  These tank farms at our refineries hold maybe 2 weeks worth of oil.  Not much.  But enough.  You see, oil doesn’t sit still for long.  For it takes about two weeks for oil on average to travel from the wells through the pipelines to the tank farms at our refineries.  So as the refineries draw down this oil in the storage tanks new oil arrives to replace it.  In a continuous, wondrous process.  That ends at the gas station.

Refined petroleum products leave the refineries pretty much the way they arrived.  In a pipeline.  The refined products are thinner and less viscous.  So the outbound pipelines are smaller in diameter.  After refining they pump gasoline into another tank farm.  These tanks feed another pipeline network.  These pipelines eventually terminate at distribution centers.  It is here where tanker trucks fill up to replenish the underground tanks at our local gas stations.  The gas entering these distribution centers is the same.  The different gas stations will add their own additives at this point to differentiate their gas from their competitors.  Then we pump it into our car.  And then enjoy the American experience of travelling the open road.  Burning gasoline that mere weeks earlier was still underground in the porous matrix of rock formations.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , ,