# Post Trip Fuel Calculation

Gas that enters the wellbore when the mud pump is shut down and pipe is being pulled from the wellbore is termed as Trip Fuel/Gas.
The gas may enter because of the reduction in bottom hole pressure when the pump is shut down, because of swabbing, or because of both.
Avgas (100-130 or 100-130LL) weight is calculated at 6 pounds per gallon; Jet A (jet fuel) at 6.84 pounds per gallon. The weights are accepted averages based on specific gravity and other variables, such as temperature and additives due to climate.

Formula

Aviation Gasoline weight per gallon(gw)=6.00
Jet A weight per gallon(dw)=6.84
Total Capacity (AvGas) Fuel Load Weight=(Fuel weight)* (gw)
Calculated Fuel Ramaining=(st)-((tt)*(gph))

TERMS RELATED TO TRIP GAS

• TRIP MARGIN
The small amount of additiona mud weigh carried over that needed to balance formation pressure to overcome the pressure-reduction effects caused by swabbing when a trip out of the hole is made.
• BOTTOMS UP
1. A complete trip from the bottom of the wellbore to the top. Pertaining to the mud and cuttings that are calculated or measured to come from the bottom of the hole since the start of circulation is termed as bottoms ups.
• BOTTOMHOLE PRESSURE TEST
A test that measures the reservoir pressure of the well, obtained at a specific depth or at the midpoint of the producing zone. A flowing bottom hole pressure test measures pressure while the well continues to flow; a shut-in bottom hole pressure test measures pressure after the well has been shut in for a specified period of time.
• TRIP
The operation of hoisting the drill stem from and returning it to the wellbore. V: shortened form of "make a trip."
• GAS ANCHOR
A tubular, perforated device attached to the bottom of sucker-rod pump that helps to prevent gas lock. The device works on the principle that gas, being lighter than oil, rises.
• SHUT-IN BOTTOMHOLE PRESSURE TEST
A bottom hole pressure test that measures pressure after the well has been shut in for a specified period of time. See bottom hole pressure test.
• TRIP TANK
A small mud tank with a capacity of 10 to 15 barrels, usually with 1-barrel or h-barrel divisions, used to ascertain the amount of mud necessary to keep the wellbore full with the exact amount of mud that is displaced by drill pipe.

Example:
Calculate the consumption of fuel post trip.
Enter Fuel Capacity in Gallons for All Tanks = 25
Enter Gallons per Hour (GPH) Consumption Rating = 1
Enter Trip Time Elapsed In Hours = 15
Enter Start of Trip Fuel In Gallons In All Tanks = 25

Solution:
Apply Formula:
Aviation Gasoline weight per gallon(gw)=6.00
Jet A weight per gallon(dw)=6.84
Total Capacity (AvGas) Fuel Load Weight=(Fuel weight)* (gw)
Calculated Fuel Ramaining=(st)-((tt)*(gph))