27 replies to this topic

[ankur2061]

Dandy,

Your experimental results are quite different from calculated values. Whether your field data is correct and whether your field measurement of the water dew point is correct I do not know. Only you are the best judge to tell this. However, please note that the spreadsheet that I have provided is for sour natural gas and that the water retention capacity of H2S and CO2 is higher than that of sweet gas. If your gas is sweet than the water content of your gas is going to be lower and higher if it contains H2S and CO2.

The spreadsheet takes input of the gas composition in terms of Methane, H2S and CO2. I hope your measured composition takes into account the presence of H2S and CO2 in the natural gas.

I have never been involved in field measurement of water dew point and hence cannot comment on whether your apparatus is working OK or not. Why don't you discuss the matter with the supplier of your hygrometer / cooled mirror system for dew point measurement. This should provide you an answer whether your dew-point measurement system is working OK or not.

Regards,
Ankur.

[Dandy Komboris]

Dear Mr. ANkur

One of your worksheet in your spreadsheet that you had provided is also Sweet Natural Gas Calculation.
When I Compare to Water Content Calculation from the book "Fundamental of Natural Gas Processing CHapter 6, Section 6.2" the result is not so different at all (almost same)

This from the water content formula from your worksheet (water content for Sweet Natural Gas Calculation) :

W_HC = 10 ^{a + b x log (P) + c x (log(P))2 + d x (log(P))}
Water content formula for sweet natural gas from "Fundamental of Natural Gas Processing CHapter 6, secton 6.2) :


Y _H2O = P _H2O ^Sat / P



P _H2O ^Sat = 10 ^{(73.649 – (7258.2/T) – 7.3037 lnT + 0.0000041653T2)}
P_H20^Sat =
saturation or vapor pressure, kPa

T = Gas Temperature, K (Temperature Range: 273.2-647.1 K)


y_H2O =
mole fraction of water in sweet natural gas
P =
Gas Pressure, kPa

Pressure is 585.1125 kPa
Temperature is 22.22 Celcius

The Result are :

a. 215.7 Lb/MMSCF (your formula)
b. 218.5 Lb/MMSCF (Fundamental of Nat. Gas Processing CHapter 6, section 2)

Does it mean your formula is correct for calculating water content of sweet natural gas ?
And the i input my gas composition
C1 = 98.51%
CO2 = 0.15%
H2S = no data so i input 0.00% (no H2S in our gas)

The result is quite same from the reading of water content of hydrocarbon from Fig 20.4 GPSA Eng Data Book 12th Edition

Here i upload the worksheet.

Please your comment Mr. Ankur

Attached Files

•  New_Correlation_for_Water_Content_of_Sour_NG (1).xls   92KB   178 downloads
•  Water_Content_Sweet_Natural_Gas.xls   24.5KB   197 downloads

[ankur2061]

Dandy,

I have checked and there is no error in the inputs. I don't know why your field measurement is so different. As I mentioned in my earlier post, maybe the measurment of dew-point is a problem. I will repeat that you need to talk to the supplier of your dew-point measurement equipment to check and re-calibrate the equipment to ensure that it is giving the correct measurement.

Regards,
Ankur.