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FTC - SWT04/21/23
Productivity
PRODUCTIVITY
FTC - SWT04/21/23
Productivity
Lecture Objectives,by the end of this lecture, YOU should be able to:
- Explain what is the P.I. (Productivity Index)- Explain what is the A.O.F. (Absolute Open Flow) and how to determine it for OIL & GAS wells.
FTC - SWT04/21/23
ProductivityPRODUCTIVITY INDEX:
P.I. Q units: bbl(STO)/day/psi
(Pi – Pwf) (used also for Gas well:
scf/day/psi)Ex: Q= 3000 BOPD
Pwf= 4500 psi P.I.= 3 bbl/day/psi
Pi= 5500 psiThat means , the well produced 3 bbls STO per day, per each psi of drawdown.
FTC - SWT04/21/23
Productivity
MAXIMUM FLOW POTENTIALor
ABSOLUTE OPEN FLOW :
The rate at which in theory a well would produce at a zero sandface (bottom-hole) back pressure.
(This rate cannot be measured and probably not achieved.)
FTC - SWT04/21/23
Productivity
•OIL WELL (AOF) Plotting BHP v/s Q on a linear
plot gives the Maximum Flow Potential or AOF.
It is called the IPR plot
I.P.R. = INFLOW PERFORMANCE RELATION
FTC - SWT04/21/23
Productivity
•OIL WELL (AOF)
Press. & Temp. dropped, oil & gas will separated
4000
2000
2000 3000
bopd
psipsi bopd
Pwf1 4000 2000
Pwf2 3000 3000
FTC - SWT04/21/23
Productivity
•OIL WELL (AOF)
Note: The slope of the IPR curve is the Productivity Index
FTC - SWT04/21/23
Productivity
•GAS WELL (AOF) Plotting pressure squared
difference v/s flowrate on a log-log plot gives the Maximum Flow Potential or AOF.
[(Pi2-Pwf2), PSIA2] v/s [SCFD]
FTC - SWT04/21/23
Productivity•GAS WELL (AOF)
Deliverability Tests:To determine flow capacity and to predict flowrate decline over the life of the well.•Gas well with AOF > 50 MMSCFD are classified as HIGH Productivity Wells.•Gas well with AOF < 50 MMSCFD are classified as LOW / AVERAGE Productivity Wells.
FTC - SWT04/21/23
Productivity•HIGH Productivity Gas Wells
A.O.F.BACK PRESSURE TEST•Clean-up, from a few hours to 24 hr.
•Initial Shut-in, twice the duration of the Clean-up•Flow at 4 different rates with stabilization on each chokes, from 4 to 8 hr on each choke.•Final Shut-in, from 12 to 24 hr.
Note:There is stabilization when: (delta P) < 0.1% WHP, every 30 min.
FTC - SWT04/21/23
Productivity•LOW Productivity Gas Wells
A.O.F.ISOCHRONAL PRESSURE
TEST•Clean-up, from a few hours to 24 hr.•Initial Shut-in, twice the duration of the Clean-up•Flow at 4 rates of equal duration (4 to 8 hr) with stabilized Shut-in periods between flow (6 to 12 hr).
•Final Shut-in, from 34 to 72 hr.
•The Final flow (4th), extends until stabilization.
FTC - SWT04/21/23
Productivity•LOW Productivity Gas Wells
A.O.F.MODIFIED ISOCHRONAL
PRESSURE TEST•Clean-up, from a few hours to 24 hr.•Initial Shut-in, twice the duration of the Clean-up•Flow at 4 rates of equal duration (4 to 8 hr) with Shut-in equal periods between flow, no matter if stable pressure has been reached or not.
•Final Shut-in, from 34 to 72 hr.
•The Final flow (4th), extends until stabilization.
FTC - SWT04/21/23
Productivity•LOW Productivity Gas Wells
A.O.F.MODIFIED ISOCHRONAL
PRESSURE TEST
- The modified isochronal test if shorter than the isochronal test because there is no need to wait for stabilization (apart for the last flow).
- It save time & money, results are less accurate.
FTC - SWT04/21/23
Productivity
- Recent software products available for WT data interpretation, offer greater flexibility of test programme needs.
- The traditional approach such as Back Pressure & Isochronal Test can be modified to reduce the numbers of flow, and hence the overall timing of the test.
FTC - SWT04/21/23
Productivity
PRODUCTIVITY
The End
