3.1- Pl Overview- Why Run Production Logs

3.1- Why Run Production Logs?

M. Watfa

Why Production Logging ? 3-Phase Flow Profile Some gas and oil entering at each zone Water entering below XX900 Bottom zone producing small amounts of each phase

Middle perforation is major source of water and hydrocarbon Top section influx is hydrocarbon only

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Why Production Logging ?

PL Applications 

%?

Evaluation of Flowing Wells  

Production profile distribution Zonal productivity & Skin Factors

%?

%?

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Why Production Logging ? Estimating Zone Pressure and Productivity Index for each zone

5300 5100 4900

Reservoir Pressure

1/PI

4700

Pressure (psi)

y = -0.3631x + 4959.1

4500 4300 4100

y = -0.129x + 4639.5

y = -0.673x + 5190.2

A

B

C

Flow Rate (bl/d

3900

0

1000

Copyright ©2001-2011 NExT. All rights reserved

2000

Material: Dr. M. Watfa

3000

4000

5000

Why Production Logging ?

Well Injectivity

Zone injectivity problem

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Why Production Logging ?

PL Applications 

Monitoring  

Changes in production profile Changes in flowing fluids: Water or Gas breakthrough

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Why Production Logging ?

Flow Profile 

Well flowing at constant choke:  

 



C

Zone Contribution Downhole reservoir data Absorption profile for injector wells identification of production problems

B

A

Different flowing Choke: 

Selective inflow performance survey

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Gas OIL Water

spinner Temperature

density

Why Production Logging ?

P1

PL Applications 

Diagnosis 

Detection of interzone cross-flow

P1 > P2 High permeability depleted zone P2 P3 > P2 P3

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Why Production Logging ? Spinner: Logging Down

Cross-Flow: detection C 

Well shut in  X-flow between perforations  This is caused by uneven depletion  This created pressure difference between the three reservoirs  and hence a (Reservoir pressure difference)  When well is closed, X-flow takes place

B

A

Which section has the Highest Permeability? OIL

spinner Temperature

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

density

Why Production Logging ?

Major Cross-Flow Field Example

Spinner



Large permeability contrast  Cross flows that reduce reservoir recovery (6,000 bl/d)  Quick remedial work needed on most wells (plugs, packers, liners, patches, re-perforations) Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Crossflow

Zubair (sandstone) 200–450 m

Crossflow

9 Sandstone members

Legend Oil Water

Why Production Logging ?

PL Applications 

Production Enhancement 

Data for workover planning:  Repair the well  Improve productivity



Completion and treatment effectiveness Corroded casing allows fluids to escape back into reservoir

Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

Corroded casing Poor cementing

Why Production Logging ? Temperature

Differential Temperature

Increasing Flow Rate

Infinite flow

Increasing Flow Rate

Temperature Profiles Without Leak For two flow-rates

dT / dD Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

0

Increasing Temp. Slope

Geothermal: zero flow

Profile with Leak

Example: Casing Leak With a leak zone above the perforations, the fluid leak produces an anomalous drop in temperature.

Why Production Logging ? The Temperature Log

dT/dD Profile of no-leak flow

Shale Hole

Oil Zone Shale Copyright ©2001-2011 NExT. All rights reserved

Profile of no-leak flow with lower flow rate Material: Dr. M. Watfa

Geothermal

Low Pressure Sand Shale Zone

Profile of flow with leak

Gas Production and Estimating AOF 4000

Total Perfs Zone B

3500 3000

Pwf: psia

2500 2000 1500 1000 500 0

-

1.00

2.00

3.00

4.00

5.00

Q: MMscf/d Copyright ©2001-2011 NExT. All rights reserved

Material: Dr. M. Watfa

6.00

7.00

8.00

9.00