3D seismic onshore: should the transition be disruptive?

Denis MOUGENOT Sercel France

Finding Petroleum, London, November 2011

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Presentation outline

• Cable system improvement over the last 10y: more channels

• Integration of cable/cableless systems within hybrid spreads

• The high productivity of the land recording systems

• How land acquisition compare with marine

• Is a disruptive transition still required?

“Conventional” cable systems are blamed (cost, weight, serial reliability…..)

and Sercel is the main manufacturer (>65% market share)

428XL (since 2005) (since 2000)

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• Channel capability of the recording systems has constantly improved to handle denser & larger spreads

More channels: Sercel’s figures

• For Land, the growth has been exponential: in average a doubling every 5 years since 45 y

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More channels: historical driver 1 • Reduction of size, weight & power for field units: - power consumption divided by 2.7 / channel in 12 years

330 mW 330 mW 140 mW 120 mW

20 c

m

SN388 / SU1 (1993) SN388 / SU1UL (1997)

408UL / FDU (1999)

428XL / FDU (2005)

- weight divided by 10 / channel in 12 years 3750 g 1450 g

420 g 350 g

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Moore's law: geophone mass halving every 5 year

0.001

0.01

0.1

1

10

100

1925 1935 1945 1955 1965 1975 1985 1995 2005 year

kg

from Dave Monk, Apache, Canadian SEG, May 2006

1945’s

1985’s

More channels: historical driver 2

- According to Moore’s law, replacement of geophones by MEMS* accelerometers is the continuation of seismic sensor evolution for the past 75 y.

* Micro Electro Mechanical System

1985’s

2000’s

• Reduction of weight for receivers:

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- one battery for every 6-8 channels - analog transmission by the cable:

. cross talk

. leakage

• Multi-Channel digitizer connected by multi-pair cables with take-outs. - excessive weight - expensive to operate and repair

More channels: multi-channel telemetry

6 channel field unit

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- robust, light & simple 4 wire cable, with digital only transmission

- efficient power management: up to 100 channels on one battery

- digitization of data at each single channel station

More channels: single channel telemetry • Today the 408UL-428XL are the only open cable systems offering:

1 channel field unit

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LAUX

1,000 Ch

2,000 Ch

FDU

• Improved performances from 408UL to 428XL:

More channels: recording capability

408UL (04/2001)

- higher rate on line (16Mbps) & transverse (100Mbps, 1Gbps)

428XL (11/2005)

2,000 Ch

10,000 Ch Ethernet

LAUX

FDU

- increased power & scalability of the central unit (n x 10k Ch)

CMXL Central Unit

Standalone SUN

PC Linux Client

HP Server

LCI Central Unit

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More channels: Central Unit scalability • 428XL client-server architecture provides flexible configurations based on PC under Linux • With laptop+GPS+LAUX (total<5kg) it even possible to record in real-time up to 2000 channels / explosive source

2,000 channel configuration

40,000 channel configuration

LAUX GPS laptop

428XL Lite

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• Two identical recorders each with 50,000 channel real-time capability in master-slave

July 09: 100,000 channel configuration

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More channels: 100,000 channel spread • Easiest spread management with the 428XL Giga transverse: 100,000 channels real-time @2ms

LCI-G

TFOI-G

LAUX-G

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More channels: towards 1M channels

NOW FUTURE

1 Gb/s 10 Gb/s

100,000 channels real-time @2ms 1 Million channels real-time @2ms

• Such 1M channel system should probably not be available at the same price, with the same weight as today’s systems

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• Flexibility of cable spread has improved thanks to: multiple telemetry supports, and multi-path telemetry

How to manage large cable spreads?

• Spread > 200km² used in desert areas

• Multiple telemetry on line & transverse to avoid obstacles using lasers, Ethernet bridges or radio relays

• Multi-path telemetry thanks to distributed electronics transmission losses avoided by rerouting data via secondary transverse or line snaking

100 Mbps 16 Mbps

line

Secondary transverse

Main transverse

snaking

Skipped digitizer

snaking 16 Mbps

100 Mbps

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Cableless for specific environments • Cableless is a cost effective solution to replace previous radio telemetry in case of obstacles (river, canyon, highways)

from COMESA

• A cableless system, is a adapted to: - specific constraints (locals, animals) - difficult environments (urban area, TZ, jungle)

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Cableless system: Unite

RAU

• System made of identical and independent stations called Remote Acquisition Units (RAU’s) based on 428XL electronics (FDU) & software (eUnite)

GPS

• All RAU’s are synchronized by GPS used for timing

Antenna (Wi-Fi) Remote Acquisition Units

(RAU’s)

• RAU’s setting, QC’s & data harvesting based on WiFi for remote access from antenna

• Over 45,000 RAU’s sold to 16 clients

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• Spread made of RAU’s only:

”Full” cableless Unite survey

• Two acquisition modes: autonomous

autonomous

and real-time

real-time

Remote harvesting

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“Infill” Unite survey for hybrid spread • Cable & cableless acquisition based on a 428XL Central Unit with two networker servers to end up with a single SegD file

• Some infill patches are harvested in real time, the others are remotely harvested

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3D “Infill” Unite in Colombia-1

2 km

3D over urban area: - no explosive allowed - no chance to lay cable - but prospective area - solution: cableless patch

- 1856 live channel template (16 lines) - 10,550 total explosive SP’s (200 SP/d)

from Sismopetrol

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3D “Infill” Unite in Colombia- 2

from Sismopetrol

Exemple of Unite infill patch in urban area

RAU & bunched phones for urban area

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3D “Infill” Unite in Colombia-3

from Sismopetrol

3D SP from FDU 3D SP from FDU + RAU

Remote harvesting with CAN Range downtown is ~300m

Country FDU + array of 6 geophones

City RAU + 6 bunched geophones

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High Productivity Vibroseis: 428XL-VE464 • Thanks to Vibrator Electronics combined with GPS and digital transmission (TDMA) up to 32 groups of vibrators can be managed in real-time over large distances

GPS + TDMA Hill

TDMA relay

VE464 DPG

VE464 DSD

428XL

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High productivity Vibroseis records

• Records obtained by a combination of 428XL & VE464 in operations from different methodologies during the last ten years

DSSS with slip-sweep

Record daily production in VP’s/d Flip-Flop

HFVS

Slip-sweep

ISS

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Simultaneous surface & borehole seismic

• VE464 DSD slave to start distant recording system

Recorder 1 (master)

Recorder 2 (slave)

TDMA DSD

DPG

VSP

• This is one step towards Total 3D seismic, and it has been already applied in the field

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Land high-end WAZ 3D surveys • Dukhan (Qatar Petroleum) WAZ HD 3D survey completed by CGGV-Ardiseis in 2009-10

• Cost land: - $140M i.e. $162,000/km² & $0.0045/seismic trace

• Main characteristics: - land, sabkha & transition zone - 863km², 35.8M traces/km² total traces >30Billion

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Marine high-end WAZ 3D surveys • Offshore Mexico (Pemex) WAZ HD 3D survey ongoing by CGGVeritas (10 months): - 2 streamer-source vessels - 2 source vessels

• Cost marine: - $200M i.e. $10,900/km² & $0.0068/seismic trace

• Main characteristics: - 18,300km², 1.6M traces/km² total traces >30 Billion

• Cost land: - $140M i.e. $162,000/km² & $0.0045/seismic trace

x15 x1.5

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Comparison of Land & Marine • Land acquisition has surpassed marine in terms of trace productivity,

data density and azimuthal distribution Land Marine - number of channels 4000 up to 100,000 4000 up to 12,000 - components 3C (PP & PS waves) 2C (PZ summation) - spread size up to 220km² up to 9km² (single vessel) - number of sources up to 18 up to 4 - data density up to 35 Million/km² up to 2 Million/km² - azimuthal distribution full offset/azimuth partial offset/azimuth - productivity (traces) up to 500 Million/day up to 80 Million/day - productivity (km²) up to 40km²/day up to 220km²/day (WAZ) • Due to land environment (topography, near surface, noise..) and to the resulting lower data quality, more traces are required onshore to get comparable images as marine: thus, the cost is higher (up to x70!)

3D seismic costs: marine to mountains

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• Signal-to-noise and resolution improve with finer spatial sampling

PSTM time slices at 900ms for symmetric source & receiver line decimations

Why High Density 3D onshore?

from P.I. Pecholcs, EAGE Land workshop, Cairo, May 2010

500m 200m 100m

• Dominant frequency (from 20Hz to 40Hz) increases

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Which recording system for the future? • It should be a scalable and flexible recording system able to manage in the same hybrid spread both cable & cableless units as well as different type of sensors (+ borehole tool …) • 428XL answers these requirements

Dig

ital

Anal

og

Cable based Cable -less

all 428XL

• The challenge will be in the capability of the system to monitor in (near) real-time an increasing number of elements

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Is a disruptive transition still required?

Receiver Cable Cableless

Sour

ce

Cen

tral

ized

Au

tono

mou

s

• Todays land recording systems have considerably improved • Various architectures are made available for productivity

• They deliver in a cost effective way seismic traces, but land will always require more traces, thus higher investment

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