By Riko Mudayana Domain Champion Schlumberger Wireline- Indonesia

Production Logging

Production Logging

The measurement of fluid

parameters on a zone-by-zone

basis to yield information about

the type and movement of fluids

within and near the wellbore.

Production Logging Applications

Monitor reservoir performance & variations

• New well performance Vs prediction

• Time lapse profile monitoring

• Layered reservoir testing

Evaluate completion performance

• Perforation effectiveness

• Stimulation evaluation

• Formation damage identification

Production Logging Applications Diagnose well problems

• Water entry

• Gas entry

• Leaks and mechanical problems

• Flow behind casing

Other

• Guidance for workover

• Enhanced oil recovery projects

• Identify boundaries for field development

Oil

Water

Basic PL Interpretation

Mono Phase Flow Rate

= Velocity x Area

Multi Phase Flow Rate

= Phase Velocity x Phase Area

Phase Area = Area x Phase Holdup

Vhy Vw

Traditional Interpretation Mixture Velocity

• Spinners

Holdup

• Fluid Density, Capacitance, Local Probes

Phase Velocities

• Correlations

Gradiomanometer Nuclear Capacitance Probe Tools

‘Holdup’ is the area fraction of the pipe occupied by the phase

of interest.

For oil-water flows: yw + yo = 1

For oil-water-gas flows: yw + yo + yg = 1

‘Cut’ is ratio of flowrates. For instance in an oil-water flow,

water cut is given by -

WC (%) = qw/(qo + qw) and more generally by:

WC (%) = qw/qt

‘Superficial velocity’ is the velocity that a phase

would have if it alone flowed in the pipe,

i.e. Q/A.

The sum of the superficial velocities is equal to the mean

velocity: Vsh + Vsl = Vm

Some Definitions

Spinner correction factor

Vaverage = C x Vf

q = C x Vf x A where,

C = velocity profile correction factor,

commonly 0.83. Better, use chart.

A = Area of flow. Use chart to convert

ft/min to flowrate for given casing.

Vf = Fluid velocity from zone calibration line.

Spinner Example 3

6000

6100

6200

6300

6400

Dep

th (

m)

0 5 10 15 20

0 5 10 15 20

Spinner rotation (rps)

Up 110 ft/min

Up 80 ft/min

Up 32 ft/min

Down 115 ft/min

Down 82 ft/min

Down 50 ft/min

A

B

C

D

Crossplot from the Example 3

Down

Sp

inn

er r

ota

tio

n (

rps)

25

20

15

10

5

0

-5

-100 0 100 200

Cable velocity (ft/min)

Up

80 215 320

Holdup Measurement

Holdup Measurement • Main purposes for making a holdup measurements:

– Determine volumetric flow in two and three-phase flow

– Show entry points in two and three-phase flow.

• Holdup measurement tools:

– Gradiomanometer* fluid density tool

– FloView (digital entry fluid imager tool)

– GHOST

– RST TPHL (Three-phase holdup log)

– NFD

– HUM

Two-Phase Flow Computation

Holdup from density

• Mass conservation:

Ao ro + Aw rw = A rlog

yo ro + yw rw = rlog

y is the “holdup”

yw + yo = 1

yw = (rlog - ro) / (rw - ro)

yw = Aw/A

yo = Ao/A

Example

• Oil density: ro = 0.7 g/cc

• Water density: rw = 1.1 g/cc

• Log density: rlog = 0.85 g/cc

• Holdup: yw = (0.85 - 0.7) / (1.1 - 0.7)

yw = 38%

Bubble flow model

Vw Vo Vo= Vw+Vs Vw

Water Oil

A

yw A (1-yw)A

Where Vs is the “slip velocity”

Two-phase Flow Computations

• Qw = Vw Aw Qw = Vw yw A’

• Qo = Vo Ao Qo = Vo yo A’ = (Vw + Vs) (1 - yw) A’

• QT = Qo + Qw

QT = (Vw + Vs) A’ - (Vw + Vs) yw A’ + Vw yw A’

= Vw A’ + (1 - yw) Vs A’

• yw QT = Qw + yw (1 - yw) A’ Vs

Qw = yw QT - yw (1 - yw) A’ Vs

Qo = QT - Qw

Two-phase Flow Computations (ctd)

QT = C Vf A

Qw = yw QT - yw (1 - yw) A’ Vs

Qo = QT - Qw

A’ = 1.39879(D2 - 1.68752)

for ID in inches

Vs in ft/min

Q in bbl/d

Two-Phase Interpretation Exercise

• Well producing both water and oil

• Casing ID: 5”

• Water Density: 1.1 g/cc

• Oil Density: 0.75 g/cc

• 3 up & 3 down passes

Is a friction correction needed?

Well Conditions Two-Phase Interpretation Exercise

6000

6100

6200

6300

6400

Dep

th (

ft)

0 5 10 15 20

0 5 10 15 20

Spinner rotation (rps)

Up 80 ft/min

Up 32 ft/min

Down 115 ft/min

Down 82 ft/min

Down 50 ft/min

A

B

C

D

Density (g/cc))

0.8 0.9 1.0 1.1 1.2

0.8 0.9 1.0 1.1 1.2

Up 110 ft/min

0 2000 4000 6000 8000 10000 6000

6050

6125

6175

6275

6300

6375

6400

Depth (m)

Flow Rate (bpd)

Use of Temperature Measurement

(the original Production Log!)

Temperature log

Spinner Temperature

geothermal gradient

Water Flow behind casing

Uses of pressure

• Well test analysis (kh, skin)

• Reservoir extent, boundaries

• Fluid conversions

• AOF, SIP determination

Advance Production Logging

†Real-time logging only

FloView

GHOST

Water Entry Detected

in High-Rate Gas Well

• Over 14 MMcf/D gas downhole

production

• Less than 120 BWPD water

downhole production

• Character of bubble count curves

indicates water recirculation in

wellbore

• Water entry at X270 seen by

Bubble counts

First oil entry

Water entry

First Oil Entry Detection

PS Platform Application Sensors

QUESTION ?