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Title

Statfjord C Seismograph Site Evaluation

Project documentation

By
O.M.
Date
16 August 2010
Version
0.1

Statfjord C. Photo: Statoil.

TABLE OF CONTENTS


1 LATEST


1.1 24 May 2011


Seismograph will be returned to factory for control.

Screenshot of last test before shipment:

Test setup 24 May 2011 (click to see large version):

Test setup 24 May 2011 (click to see large version)
Test setup 24 May 2011 (click to see large version)

1.2 26 Nov 2010


26 Nov 2010: Received Seismograph mounted in EEx-d enclosure, ready for pre-deployment test. Click to see pictures

26 Nov 2010: Received Seismograph mounted in EEx-d enclosure, ready for pre-deployment test. Click to see pictures.

We will modify mounting method so seismograph rests on bottom of EEx-d enclosure instead of mounting plate - if we keep first method, the seismograph and mounting plate constitute a mechanical system with resonance frequencies that could influence measurements.

Mounting plate modification
Mounting plate modification completed. Seismometer now rests on bottom of EEx-d enclosure; at the same time, height adjustment screws located near bottom of seismograph are easily accessible.

1.3 02 Dec 2010


Predeployment testing 02 Dec 2010
Predeployment testing 02 Dec 2010

NOTE: Documentation below is not updated - so unit shown does not reflect what's specified ....



2 INTRODUCTION


We consider installing a seismograph on one of the platforms on Statfjord field, in the North Sea.
The seismograph will be positioned at the bottom of one of the concrete platform legs.

A temporary installation will first be done as site evaluation, using a seismograph with internal data storage.
It will be powered by 230 Vac from platform electrical network, and furnished with a 12 V, 7 Ah NiCd
trickle-charged backup battery, sufficient to keep the seismograph operating for at least 24 hours should
power outages occur.

Seismograph, including data storage media, NiCd battery package and charger, is to be placed in explosion proof housing.



3 FUNCTIONAL DIAGRAM


Click to open PDF document:

Click to open PDF document.
Functional diagram (click to open PDF version).



4 SEISMOGRAPH GÜRALP MOD. CMG-6TD


4.1 Specifications


Güralp Mod. CMG-6TD
Seismograph Güralp Mod. CMG-6TD.

Specifications (subset of relevance here; source here):

Parameter Value
Sensitivity 2000 V/m/s
Nominal output sensitivity 2.0 × 10-9 m/s/count
Standard output format 24-bit
Noise-free resolution (NPR) at 20 samples/s > 132 dB r.m.s. (> 22 bits)
Standard frequency band 0.033 Hz (30 s) – 100 Hz
Operating temperature range –10 to +75 °C
Pressure jacket material Hard anodised aluminium
Sensor base plate Hard anodised aluminium
Base diameter 154 mm
Sensor height 242 mm (including handle)
Sensor weight 3.0 kg
Voltage requirements 10..24 V using 12 V DC/DC converter
Current at 12 V DC with GPS 165 mA1)
Nominal current at 12 V DC without GPS 75 mA2)

1) GPS not used. We will use 75 mA in power estimates.
2) Ref. page 16 in GMG-6TD Operator's Guide, Issue D.



4.2 Calibration sheet


Calibration sheet for Mod. CMG-6TD-0001 S/N T6278 is placed in project file. It can also be requested from the manufacturer.



4.3 Data storage considerations


Quote from manual p.5:

"The 6TD can be supplied with up to 16 Gb of internal Flash memory for data storage."

The unit we use, however, only has 4 GB storage.

Estimate of storage duration:

  • No. of channels: 3
  • Sampling rate: 100 Hz
  • Bytes/sample/channel: 4
  • Bytes per hour: 3 * 4 * 100 * 3600 = 4.32 Mbyte
  • Bytes per day: 4 320 000 * 24 = 103.68 Mbyte
  • Duration of 4 GByte: 4000 MByte / 103.68 MByte/day = 38.6 days

Assumed 1 MByte = 1 000 000 bytes - check!

With 4 GB internal memory, the unit can store data for 38.6 days.



4.4 Instrument power input / data output port


Connector pin-out Cable connector details

Instrument connector.
19-pin plug MIL-DTL-26482, typical P/N: 02E-14-19P

Instrument output port, pin designation.
Mating cable connector [typical P/N: ***-14-19S]. Connector pin-out:
Ref. p. 8 in Amphenol "Miniature Cylindrical Connectors" datasheet.
Insert arrangement 14-19. Front face of pin insert.
Insert arrangement 14-19. Front face of pin insert.

Front face of pin insert illustrated.

Supplier: ELFA

Supplier: Farnell



4.5 Breakout box


Manufacturer Güralp
Model CMG-SCU-0062
Designation CMG-6TD Breakout Box
The CMG-6TD breakout box.
The CMG-6TD breakout box (Güralp model CMG-SCU-0062). From left to right: Power, GPS, Data.
Connector pin-out Cable connector details
DATA PORT

6-pin plug MIL-DTL-26482, typical P/N: 02E-10-06P

Breakout box data port, pin designation.
Breakout box data port, pin designation.
Mating cable connector [typical P/N: ***-10-06S]:
Insert arrangement 10-6. Front face of pin insert.
Insert arrangement 10-6. Front face of pin insert.

Supplier: ELFA

Supplier: Farnell

Supplier: RS

  • Connector:
    • P/N: 450-354
    • MFR: Amphenol
    • MFR PN: 62GB-56T10-06SN
  • Strain relief cable clamp
    • P/N: 450-512
    • MFR: Amphenol
    • MFR PN: 62GB-585-10-06S
GPS PORT

NOT USED

6-pin plug MIL-DTL-26482, typical P/N: 02E-10-06S

N/A
POWER PORT

10-pin plug MIL-DTL-26482, typical P/N: 02E-12-10P

Breakout box power port, pin designation.
Breakout box power port, pin designation.
Mating cable connector [typical P/N: ***-12-10S]:
Insert arrangement 12-10. Front face of pin insert.
Insert arrangement 12-10. Front face of pin insert.

Supplier: ELFA

Supplier: Farnell

Supplier: RS

  • Connector:
    • P/N: 450-376
    • MFR: Amphenol
    • MFR PN: 62GB-56T12-10SN
  • Strain relief cable clamp
    • P/N: 450-534
    • MFR: Amphenol
    • MFR PN: 62GB-585-12-10S



4.6 Battery capacity needed for 38 days recording


The seismograph that will be deployed is furnished with 4 GB internal memory, which (ref. estimate above) can store data for 38 days.

Without GPS, current consumption is estimated to 75 mA (12 Vdc voltage input).

Power supply arrangement can possibly be made much simpler if we could use a battery package that could feed the seismograph for the 38 days in question. We must ensure that seismograph handles a completely run-down battery, which will happen if data collection is not terminated in time.

Energy needed for 38 day operation, 75 mA current drain:

  0.075A * 24h = 1.8 Ah per day

Energy needed for 38 days recording: 1.8 Ah * 38 days = 68.4 Ah

In order to consider a 38 day period running on batteries ONLY, we must c



4.7 Configuration


Configuration and testing of Güralp CMG-6TD is performed by the Scream! software (contact Güralp to obtain a copy). Click to see large screenshot.

Screenshot of Güralp Scream! software (click to see large image).
Screenshot of Güralp scream! software (click to see large image).



5 POWER SUPPLY


5.1 Introduction


  1. To ensure operation during failure or absence of external power source, the unit should be furnished with NiCd
    battery connected to battery charger. The charger is powered from external 230 Vac. Both battery and charger
    should be placed within EEx container.
  2. The battery capacity should be sufficient for 24 hour operation in case of power outage.
  3. The unit should provide the possibility of completely isolating the battery from both the load (i.e. the seismograph)
    and the charger.

UPDATE 24 May 2011: We decided to use an ordinary 230 Vac input / 12 Vdc output power supply, without any NiDc battery bank to provide energy should mains supply fail for any reason. It was assumed that the seismograph could endure intermittent mains power outages and just start logging again when power was restored.

Power supply selected:

Even though the CMG-6TD uses < 100 mA (no GPS) we specified a supply capable of 1 Amp output to handle any peak currents at start-up. In addition, it's linear with fairly low ripple and good load/line regulation figures.



5.2 Battery capacity needed for 24 h operation in case of power outage


Battery capacity calculations are based on stated seismograph current consumption:

Current at 12 Vdc, without GPS: 75 mA. Ref. p. 114, Section 9 "Specifications", in CHG-6TD Operator's Guide.

Estimate of 24 hour energy usage: 0.075 A x 24 h = 1.8 Ah

5.2.1 Conclusion:

Seismograph 24 h energy need is 1.8 Ah. In order to avoid deep discharge of the battery unit, we use a factor x4 when specifying minimum battery capacity: 1.8 Ah * 4 = 7 Ah.



5.3 Battery specifications


A suitable battery assembly could consist of 10 ea Sanyo KR-7000F, each 1.2V, 7Ah NiCd battery.

Subset of the Sanyo KR-7000F specifications that have most relevance for our application:

Parameter Value
Capacity (mAh) at 0.2C discharge rate (minimum) 7000mAh
Charging Current 700mA
Discharge condition End Volt 1.0V at 20 deg C
Dimensions, diameter x height [mm] 33.2 x 91.0
Area and volume, stack of 10 batteries, arranged as 5 x 2
  • Area: (2 x 33.2 mm) x (10 x 33.2 mm) =>
    66.3 mm * 332.0mm = mm2
  • Volume: 66.3 mm * 332.0mm * 91 mm = mm3



6 WIRING DIAGRAM SEISMOGRAPH/EEX-D UMIT


From the signal/power connector on the seismograph, the following signals are led to terminals:

  Signal name      J1/SEISMOGRAPH           POWER SUPPLY         X3 TERMINAL BLOCK
  ---------------------------------------------------------------------------------
  Power +12 Vdc ------  A  ----------------  + 12VDC
  Power 0 V ----------  B  ----------------    0 V
  RS232 TXD ----------  C  -----------------------------------------   X3-1 
  RS232 RXD ----------  D  -----------------------------------------   X3-2
  RS232 RTS ----------  E  -----------------------------------------   X3-3
  RS232 CTS ----------  F  -----------------------------------------   X3-4



7 EEx-d CONSIDERATIONS


7.1 EEx-d container


Due to requirements regarding location of electronic equipment in hazardous areas, EEx-d rules will have to apply for the installation.

EEx-d container specifications:



7.2 EEx-d container drawing




7.3 Batteries used in EEx-d containers


Use of batteries in EEx-d enclosures is regulated by IEC publication no. 60079-1 (Ed. 6.0, 2007-04) Annex E.

Primary (non-rechargeable) cells

A 12 V / 68 Ah battery would be needed to keep the seismograph operating for 38 days (when storage memory is filled).

On p.62 (Annex E) the IEC 60079-1 lists a number of acceptable primary type electrochemical systems:

Positive electrode Electrolyte Negative electrode
Manganese dioxide Ammonium- or zinz chloride Zinc
Manganese dioxide Organic Lithium
Thionyl chloride (SOCl2) Non-aqueous inorganic Lithium
Manganese dioxide Alkali metal hydroxide Zinc
Silver oxide Alkali metal hydroxide Zinc

Table of acceptable electrochemical systems - primary cells. (Excerpt from Annex E of the IEC 60079-1).

Secondary (rechargeable) cells

On p.63 (Annex E) the IEC 60079-1 lists a number of acceptable secondary type electrochemical systems:

Type Electrolyte
Nickel-cadmium Potassium hydroxide
Nickel-metal hydride Potassium hydroxide
Lithium Non-aqueous organic salt
NOTE - DATA AWAITED - PROBABLY NOT PERMITTED

Table of acceptable electrochemical systems - secondary cells. (Excerpt from Annex E of the IEC 60079-1).



7.4 Hazardous area information


Excerpt from TNBCD datasheet:



8 CONFIGURATION AND TEST 7 DECEMBER 2010


8.1 External GPS connected to PC


GlobalSat Mod. BU-353

GlobalSat mod. BU-353
GlobalSat mod. BU-353

8.2 Config: Set system ID


8.3 Config: Output control


8.4 Config: Disable triggering (want continuous recording)


8.5 Config: Mux channels setup


8.6 Reset flash memory


8.7 Set FILING MODE


  • All data stored in flash memory
  • Only Heartbeat messages on serial output - and Heartbeat interval set to 10.0 seconds
  • Open Status message stream (labelled 0 Samples per second [SPS]). Select AUTO-REFRESH. Status message window will be updated every 10.0 seconds.'

Reset seismograph, and confirm that settings take effect:

8.8 Time synchronization


8.9 Inject calibration signal


8.9.1 It seems that the same calibration is applied to all three channels at the same time, when you select the Z channel (and the others don't work).

8.10 Check that data is stored in flash


Verify that "Blocks of data in flash file buffer" increases.



9 DOCUMENT VERSION CONTROL


Version number By Date Approved by Date Details
0.1 O.M. 16 August 2010 - - Draft version
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