Exactly how many gallons of pure gasoline are in a barrel of crud oil?

Question

So a barel of crude oil = how many gallons of gas

Answer 1

Apparently there are many variables.  I have seen anywhere between 5 and 30% efficiency.

Answer 2

Read this:

http://www.newton.dep.anl.gov/askasci/en...

Answer 3

I am guessing you mean crude oil, not crud oil.

The answer is none, CRUDE has to be refined to get gasoline.

Answer 4

That depends on both the oil and the refining process.  

Crude oil comes from a lot of different places and can be very different in character and quality.  Some oils are very thick and tarry, and have little natural gasoline in them.  (Examples are tar sands in Canada, La Brea Tar Pits in downtown Los Angeles, crude oil from the wells in Salt Lake City, and much of the crude form the North Slope in Alaska.)

Some crude oils are very light and fluid and have a lot of natural gasoline and light oils.  Examples would be Light Arabian from the middle east, and west Texas crude oils.

The way the oil is processed or refined can also make a difference in how much gasoline you get.  The simplest process is to just boil the oil.  The various components in the crude oil boil at different temperatures, and are captured, or drawn off as they vaporize out of the hot crude oil.  Gasoline is pretty light, and comes off very early in the process.  This is the old traditional refining process.

The refiner can also use chemical and physical processes to convert some of the heavier oils to gasoline.  Heating the heavy oils to very high temperatures can cause some of the heavy oils to literally break apart into smaller molecules of gasoline.  This is called cracking or coking. - It is difficult, messy and expensive, but it can convert heavy oils and asphalts into lighter components like gasoline and heating or fuel oils.

Another process uses chemical catalysts at high temperatures and pressures to break apart heavy oil molecules and/or reform them into lighter components like gasoline.  Typically metals like platinum and palladium, which are very expensive - on the order of $1,000 to $2,000 per ounce - are used.  This is called catalytic cracking or reforming.

So, the answer of how much gasoline you get from crude oil depends on how much effort and money you are willing to spend.  Light sweet crude with lots of natural gasoline is much more expensive than heavy sour asphaltic crude oils.  Simple distillation is less expensive than thermal cracking or catalytic conversion.  

Most old refineries used simple boiling, or distallation techniques.  A few years ago there was still an old pot still, left over from the early 1900's,  in one of the refineries just across the bay from San Francisco - nothing more than a giant metal pot with an inverted funnel above it.  They would boil the oil in the pot,  collect the gasoline fumes in the inverted funnel, and let it condense into barrels.  They would throw away the stuff that was left in the pot after the gasoline boiled off - diesel oil, heating oil, fuel oil, asphalt.

In the 1920's through the 1950's, demand for oil increased rapidly, and a lot of refineries were built with better distaillation technologies.  In the 1970's, the OPEC oil embargo stopped the flow of light sweet crude from the middle east, and refineries began to develop catalytic cracking technologies.  Many, but not all, refineries added or retrofitted new technologies to their existing facilities, and can post-process heavier distillates to convert them to gasoline.

As mentioned above, typical ranges are in the 5% to 30% ranges for simple distallation.  Some crude oils have little or no natural gasoline, and it isn't cost effective to try to get any out of it, so 0% is the low end.  30% is probably about the max.  when you add themal or catalytic cracking, you may get another 20% - 25%, for a total  of about 55%.

A barrel of oil in the oil industry contains 42 gallons.  Listed below is the summary of refining a barrel of California crude oil.  Data is from

http://www.energy.ca.gov/gasoline/whats_...

Product                                  Percent of Total

Finished Motor Gasoline     51.4%

Distillate Fuel Oil                  15.3%

Jet Fuel                                  12.6%

Still Gas                                   5.4%

Marketable Coke                    5.0%  

Residual Fuel Oil                    3.3%

Liquefied Refinery Gas          2.8%

Asphalt and Road Oil             1.9%

Other Refined Products         1.5%

Lubricants                                0.9%

One barrel contains 42 gallons of crude oil. The total volume of products made from crude oil based origins is 48.43 gallons on average - 6.43 gallons greater than the original 42 gallons of crude oil. This represents a "processing gain" due to the additional other petroleum products such as alkylates are added to the refining process to create the final products.

Additionally, California gasoline contains approximately 5.7 percent by volume of ethanol, a non-petroleum-based additive that brings the total processing gain to 7.59 gallons (or 49.59 total gallons).

Source: California Energy Commission, Fuels Office, PIIRA database. Based on 2004 data.