7 Icruise Downlink Analysis

DOWNLINK ANALYSIS
DOWNLINK ANALYSIS
HMS and
Post-Drilling iCruise docs
Procedures
Best practice Tool Theory

Troubleshooting
Pre-Job
Vibration Mobilization
Downlink Analysis Pre-Drill

Procedures
GeoSpan Drilling
Operations
iCruise
CruiseControl
© 2018 Halliburton. All rights reserved.

Learning Objectives
 At the end of this session, you should be able to
 Describe how a pulse is detected by PWD

 Describe Z’s functionality
 Analyze downlink troubleshooting

GEO-SPAN® Downlink Schematic

General Information
 The downlink system is designed to communicate from the surface to the

downhole tool string
 Geo-Span® - Bypass of mud from SPP – Creates a low frequency negative
pulse
 PWD tool detects the downlinks and calculates the time between pulses
 The same pulsing scheme is used to MPT – Negative Pulse detection
 Downlink communication allows modify downhole parameters or setting
while drilling

General Information
NOTE:
 The downlink threshold setting is NOT in units of pressure.

 All the Z’s are in correlation units, which represents how well the
downlink pulse shape correlates or matches the hard-coded pulse
reference
 Higher correlations values indicate a stronger relation between them.

Downlink Pulse Amplitude
 Keep in mind that for the downlink pulse, the difference in pulse amplitude
between the surface and PWD is not due to attenuation but primarily due to a
significant difference in flow resistance between the surface to bottom as
compare to PWD to bottom.
 The 200 psi pressure (Busmaster) and 500 psi (Slave mode) drop below the
PWD is a good default recommendation to follow because it provides a good
amplitude pulse without having to bypass excessive fluid through the skid.
 Pressure drop below the PWD and percentage fluid bypass control the pulse
amplitude.

Downlink Pulse Amplitude
 Amplitude = (Qclosed^2 – Qopen^2) x (R below PWD)
 Qclosed = Flow through drill string when NOT pulsing

 Qopen = Flow through drill string when pulsing
 (Qclose – Qopen) = flow through skid
 R below PWD = flow resistance below the PWD tool
 BYPASS (%) = 1- ((P1-P2/P1)^0.5)
 P1- Stand Pipe Pressure while drilling (Choke Closed)

 P2 – Amplitude of pulse on surface during downlink

Geo-Span® / RT PWD Data
 Z1 - Std Dev Valid Pulse Amplitude
 Z2 - Mean Valid Pulse Amplitude
 Z5 - Number of Detected Pulses
 Z6 - Std Dev Correlation Waveform
 Z7 - PWD Threshold Setting

Z7 – PWD Threshold Setting
This parameter is the value of the Downlink Threshold Setting. The Setting should
be monitored when changing the downlink Threshold using the Threshold
Correction command to ensure that the setting is set at the proper value.

VDF Data Items Related to Downlink
 The PWD threshold (Z7) is not a fixed value.
 The deeper becomes, more difficult turns to physically send downlink to the PWD
downhole.
 There isn't a rule of thumb to determine if the threshold will always increase or
decrease. We have to analyze the data that we have and choose the best option.
 It’s import to follow all these values (Z1, Z2, Z5, Z6, Z7) on real-time while drilling to
avoid downlink problems. An analysis of the values will help to take the right
decisions preventing and solving downlink problems
If there is not enough prior field experience setting up PWD threshold, the iCruise® PWD
downlink threshold setting should be set to 350 correlations unit (CU) higher than the external
PWD downlink threshold. For example, if external PWD downlink threshold is expected to be 300
CU, iCruise PWD downlink threshold should be set to 300+350 = 650 CU.
For all iCruise® firmware versions prior to Bundle v.314A, the PWD downlink threshold cannot be
changed through downlink while using the iCruise® PWD sensor.

Z2- PWD Mean Valid Pulse Amplitude
 This parameter is the mean (average) of pulse amplitudes of all detected in a

valid downlink message by PWD.
 This parameter is only update if a downlink message is detected as valid (passes

the parity check). Otherwise, the parameter will repeat the value calculated for
the last valid downlink message.
 Pressure drop below the PWD and percentage fluid bypass control the pulse
amplitude.
 If this parameter is approaching the downlink threshold setting, the choke size
and/or flow rate in the downlink skid should be increased to generate a higher
pulse amplitude, which will generate a higher VPA(valid pulse amplitude).

 Ideally, the mean VPA should be at least 150-200 correlations units above the
downlink threshold setting (Z7).
Calculating Z2:
 The Z7 is set to 250 correlation units. A downlink message was detected and
passed the parity check. The message transmitted 4 pulses. The four pulses
amplitudes of the four peaks detected are 480, 475, 490 and 510.
Z2 = (480+475+490+510/4 = 488.75 (correlation unit)
 Note that, in this case, Z2-Z7 (488.75-250) > 150.

Z2 –INSITE DATABASE- PWD DL Diag VPA
Z2 increased
from 382 to 473

Z1- PWD Standard Deviation (SD) Valid Pulse Amplitude
 This parameter is the standard deviation of the pulse amplitudes of all peaks
detected in a valid (parity passed) downlink message detected by PWD.
 A smaller SD (less than 50) indicates that the amplitudes of the downlink
pulses are steady and consistent.
 A larger SD deviation (greater than 50) indicates that the amplitudes of the
downlink pulses are irregular and inconsistent.
 This parameter is only updated if a downlink message is detected as valid
(passes the parity check). Otherwise, the parameter will repeat the value
calculated for the last valid downlink message.

 Based in the first example, for detected pulse, 480- 475- 490-510 correlation units,
calculate Z1:
• Average = Z2 = 488.75 • ∑ (189.02 + 76.56+1.56+451.56)/(4-1)
• (475 – 488.75)^2 = 189.02 • SD= 15.47 (in correlation unit)
• (480-488.75)^2 = 76.56
• (490 – 488.75)^2 = 1.56
• 510-488.75)^2 = 451.56
Z1 decreased
from 82 to 77

Z5- PWD Number of detected Pulses (NPD)
 This parameter is a count of the number of pulses detected by the PWD tool.
 The counter has a range from 0 to 255. When counter reaches 255, the next
detected pulse will roll the counter back to 0 and then continue incrementing for
subsequent detected pulses.
 A detected pulse is declared when the cross-correlation signal exceeds the

downlink threshold setting (Z7). This parameter is very helpful in determining if
pressure noise is exceeding in downlink threshold setting.

Each time the parameter is pulsed to the surface, the difference between the new
real-time parameter and the last real-time parameter is the number of detected
pulses during the time between the two real-time parameters.

 The value of this parameter should not increment between two real-time updates
unless there was a pump cycle or a Downlink message initiated from the surface.
 If downlink was NOT send or cycle pumps were NOT applied and NPD is
increasing, pressure noise is exceeding the Z7.
 Z7 should be increased using downlink the Downlink Threshold Correction

command until the setting is above the amplitude of pressure noise.

Phantom Pulse
 A pump cycle may generate up to 2 phantom detected pulses
 The pressure spike generated when bringing the pumps up and shutting the pumps
down usually causes a phantom detected pulse.
 This phenomenon may or may not occur on every pump cycle.

Z6- PWD Standard Deviation Correlation Waveform
 This parameter is the standard deviation of the correlation waveform for the
pervious five minutes of pump-on data.
 The value of this parameter is only useful when NO downlink messages were
initiated five minutes prior to the real-time parameter being detected by Insite
 Z6 is used to determine if noise amplitude could cause false pulses or/and

corrupt valid downlink messages.

 If no Downlink messages were initiated during the previous five minutes, the
standard deviation multiplied by three (also written 3 sigma [σ]) will indicate the
approximate of pressure noise.
 The correct course of action would be to increase the downlink Threshold setting
by at least 100 correlation units above the Z6*3. In other words, ideally, Z7 ≥
100+Z6*3.
 Bear in mind that Z6 is only valid with NO downlink is sent during the five minutes
after pipe connection and/or pump cycle.

Z6 Example
Z6 is 17 units. Thus Z7
≥ 100 + 3*17

Message Log Viewer
(Session Log)
Z1
Z2
Z7
Z5
Z6

Geo-Span / PWD
800
Z5 1 2 3 4 5 6
Z1 Std Dev VPA
600
Z2 VPA Mean
400
Z7 PWD Threshold
200
3 x Z6 – Std Dev Corr WF
0
-200
-400
-600
0 50 100 150 200 250 300 350

Geo-Span / PWD
600 Z2
400 Z7
3 x Z6
200
90% of Background Noise is under 3 x Z6 when not downlinking

-200
-400
-600
0 50 100 150 200 250 300 350

Geo-Span / PWD
 General Rules
 Detection Threshold Default of 250
 Threshold should be 100 units above three times Std Dev of Corr
Wave (Z6)
 Aim to have a VPA Mean (Z2) 150 to 200 units above Threshold
 Number of Detected Pulses

 Runs from 0 to 255 and wraps round
 Adds one for every valid and invalid pulse detected
 Adds 2 for each pump cycle (phantom pulses)
 If increasing while not sending then you are picking up noise - Raise threshold.

Geo-Span / PWD
600
VPA Mean
3 x VPA Std Dev
500
16 Jet 18 Jet
400
Correlation Counts
300
DETECTION THRESHOLD 250
200
100
0
2000 2500 3000 3500 4000 4500 5000
Depth

Downlink Analysis (Rea-Time Monitoring)



The Downlink Advisor™
 The Downlink Advisor feature has been introduced within INSITE 9.2 Service Pack 3 in order to fill the
gap and provide knowledge and the tools necessary to maintain downlink health in all runs.
 It is mandatory to use it in all jobs where downlinks are being sent and it is open within RT Manager
application in INSITE.
 Once RT Manager is open, the Downlink Advisor Chart will also be open by default and it will update
with all historical PWD diagnostic data (Realtime) from current run. If user wants to focus on latest
drilling activity he can zoom in to the latest portion of the chart.

The Downlink Advisor™
Z7 & Z2 & Z1
Z7 & Baseline line (Z6x3)

The Downlink Advisor™ - Invalid” Baseline Noise (Z6x3) Chart Representation
 Advisor is considering Z6 valid when received X minutes after “Detection Enabled” is seen:
o X = 5 min for pump cycle events.
o X = 8 min for Downlink events. Eight minutes was chosen for the downlink event logics
implementation to account for time differences when a Downlink finishes being sent.
 Two main actions are being perform in the chart to differentiate valid vs. invalid baseline noise (Z6x3) if
Z6 is received within 5 or 8 minutes of a pressure event:
o It is plotting Baseline Noise (Z6x3) with BLACK dots instead of regular color.
o It is NOT plotting the potential threshold optimization zone (Bottom Yellow) but rather considering
the neutral (Dark) zone.

 It is plotting Baseline Noise (Z6x3) with BLACK dots instead of regular color
 The dark zone surpasses any bottom-yellow zone along with black dots – indication that during this
period, any Baseline noise (Z6) is invalid. – Example of Invalid CW after pumps-on (5min)

 Green Bar – Indicates a Downlink was sent

and a “Success” reply was received.
 Orange Bar – Indicates a Downlink was

sent and a “Timed-Out” reply was received.
A Timed-Out bar is plotted in orange as it
can be indeed a miss (if downlink was not
received) or actually a false Timed-Out (if
downlink was received downhole but reply
was not decoded on surface).

The Downlink Advisor™ - ALARMS
 Baseline Noise Too High – It is plotted when valid Baseline Noise approaches the Threshold within
the No Go zone (Middle Red).
 VPA Too High – It is plotted when Mean VPA enters the VPA No Go zone (Top Red).
The Downlink Advisor™ - ALARMS
 If the user hovers the mouse pointer

towards any of the zones, the messages
described below will show up and can be
used as guidance for actions to perform.
• INSITE 9.2 Service Pack 3 also reinforced the

GeoSpan nozzle size information capture, which is
now called for within the Downlink server window
under Configure/Parameters.
• It is mandatory to enter a nozzle size when

choosing GeoSpan skid as the Downlink system.
Knowledge Check
According with the scenario below, verify and explain if the DL quality control
variables are according with the basic rules for PWD DL detection:

Workbook Exercise / Game Plan project
1. Individually answer the questions in practical 6 of your workbook
2. Update the Game Plan based in the learning content covered in this section.

Questions?

DOWNLINK ANALYSIS
HMS and
Post-Drilling iCruise docs
Procedures
Best practice Tool Theory

Troubleshooting
Pre-Job
Vibration Mobilization
Downlink Analysis Pre-Drill

Procedures
GeoSpan Drilling
Operations
iCruise
CruiseControl

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7 Icruise Downlink Analysis

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DOWNLINK ANALYSIS

Best practice Tool Theory

Downlink Analysis Pre-Drill

© 2018 Halliburton. All rights reserved.

 At the end of this session, you should be able to

 Describe how a pulse is detected by PWD

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

 The downlink system is designed to communicate from the surface to the

© 2018 Halliburton. All rights reserved.

 The downlink threshold setting is NOT in units of pressure.

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

 Amplitude = (Qclosed^2 – Qopen^2) x (R below PWD)

 Qclosed = Flow through drill string when NOT pulsing

 BYPASS (%) = 1- ((P1-P2/P1)^0.5)

 P1- Stand Pipe Pressure while drilling (Choke Closed)

© 2018 Halliburton. All rights reserved.

 Z1 - Std Dev Valid Pulse Amplitude

 Z2 - Mean Valid Pulse Amplitude

 Z5 - Number of Detected Pulses

 Z6 - Std Dev Correlation Waveform

 Z7 - PWD Threshold Setting

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

 The PWD threshold (Z7) is not a fixed value.

© 2018 Halliburton. All rights reserved.

 This parameter is the mean (average) of pulse amplitudes of all detected in a

 This parameter is only update if a downlink message is detected as valid (passes

© 2018 Halliburton. All rights reserved.

Z2 = (480+475+490+510/4 = 488.75 (correlation unit)

 Note that, in this case, Z2-Z7 (488.75-250) > 150.

© 2018 Halliburton. All rights reserved.

Z2 –INSITE DATABASE- PWD DL Diag VPA

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

• (475 – 488.75)^2 = 189.02 • SD= 15.47 (in correlation unit)

• (490 – 488.75)^2 = 1.56

© 2018 Halliburton. All rights reserved.

 A detected pulse is declared when the cross-correlation signal exceeds the

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

 Z7 should be increased using downlink the Downlink Threshold Correction

© 2018 Halliburton. All rights reserved.

 A pump cycle may generate up to 2 phantom detected pulses

 This phenomenon may or may not occur on every pump cycle.

© 2018 Halliburton. All rights reserved.

 Z6 is used to determine if noise amplitude could cause false pulses or/and

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

90% of Background Noise is under 3 x Z6 when not downlinking

© 2018 Halliburton. All rights reserved.

 Number of Detected Pulses

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.

© 2018 Halliburton. All rights reserved.