Week 11 Challenge

Week 11 challenge:

Q-1. For the following condition which type of 3 phase separator is suitable?

1. Oil flow rate – 5000 bbl/day
2. Water flow rate – 2000 bbl/day
3. Gas flow rate – 1.2 MMSCFD (million metric standard cubic feet per day)

For these conditions, horizontal separator with boot is suitable. This kind of separator is typically used to separate light liquid form the heavy liquid.  Because here the heavy liquid (water) quantity is less compared to the light liquid (oil). The heavy liquid is collected in the boot available at the bottom of the separator.

Q-2. For the following determine the water flow rate, gas flow rate based on the water cut and gas to liquid ratio. Also specify which type of three phase separator is suitable.

1. Liquid flow rate – 12000 bbl/day
2. Water cut – 25%
3. Gas to liquid ratio – 0.2 MMSCF/bbl

Given conditions,

Liquid flow rate – 12000 bbl/day

Water cut – 25%

And Gas to liquid ratio – 0.2 MMSCF/bbl

Therefore, water flow rate = 12000*0.25 = 3000 bbl/day

Gas to liquid ratio = 12000*0.2 = 2400 MMSCF/day

Here, horizontal three phase separator with boot is used because of the differences in the quantity.

Q-3. Estimate the gas composition from the two phase separator with 2 lb/MMScf carryover of liquids into the gas stream using HYSYS. Inlet stream conditions

1. Operating pressure – 2barg
2. Vapor fraction – 0.3
3. Composition

1. Hexane – 0.2 mol %
2. Heptane – 0.3 mol %
3. Nonane – 0.3 mol %
4. Decane – 0.2 mol %

1. Inlet mass flow rate – 8000 lb/hr

The conditions and composition of the stream are

Spreadsheet calculations:

In the problem only 2 lb/MMSCF carry over liquid in the gas stream is given. It is identified that the value is negligible when calculating the final gas stream values. So the liquid carry over value increased to 20 lb/MMSCF. The results are given below in the screen shots.

Gas stream composition with carryover liquids.