ZLand® Nodal System

The ZLand® system is comprised of three main components:

• Autonomous Recording Unit (ARU) and the Hand Held Terminal deployment aide (HHT)
• Source Coordinator and Store and Forward Environment (SAFE)
• Data Recording Station (DRS) consisting of the Data Harvester Section and Data Sorter System

ZLand® specifications (PDF download)

ARU

The ARU is the field unit used to record, filter and store a single point of seismic reflections for an extended time period – it is considered to be the heart of the ZLand® system.  The unit requires no cable or radio telemetry infrastructure for deployment.  When deployed and operational, there is no communication between the independent ARUs or between an ARU and a Central Unit.

Each ARU is completely self-contained with all necessary circuitry safely encased in a high-impact nylon polymer shell.  The absence of external cables and other external components makes it invulnerable to the environment.  Owing principally to the lack of cables, the ZLand® spread is free from troubleshooting so that what would essentially have been lost time is converted directly into production time.  This enables a faster shooting program for earlier completion of a project.

ZLand® is a continuous recording system designed to acquire and record seismic data onto internal FLASH memory for 288 hours, or 12 days.  The power supply to the ARU can be partially shut down and the unit put into a sleep mode to further extend – possibly doubling or more – the time an ARU can remain at a particular receiver location.  The units can acquire seismic data using any type source via any known technique; they also can acquire passive seismic data.

Each ARU maintains a system-wide synchronized timing to within +/- 100 microseconds relative to Coordinated Universal Time (UTC).

HHT

The HHT –  a GPS positioning device utilizing proprietary FairfieldNodal software – is used to position, initiate, deploy and test the ARU when laying out the receiver spread.  When an HHT is attached to the top of an ARU, a bi-directional serial communication link is established.

The deployment location from the HHT is loaded into the ARU, which will respond to the HHT with its serial number and report the status of internal tests.  All this information is recorded in the internal deployment log FLASH memory of the HHT, and the HHT log is transferred to the Spread Management System to provide inventory management and spread deployment status information.

The Source Coordinator

The Source Coordinator is used to coordinate source activation and location

The compact, portable ZLand® Source Coordinator is comprised of:

• GUI operator interface loaded onto a laptop PC
• Source Encoder(s) used to synchronize the various sources
• Store and Forward Environment (SAFE) device that issues a GPS synchronized START command to the Source Encoder and then detects and timestamps the corresponding TIMEBREAK event
• One or two sets of radios for voice and synchronization information between the Source Coordinator operator and the assorted sources

The Source Coordinator can be packed into a small-footprint vehicle or lightweight helicopter – or even personally carried.  The entire package also can be loaded into a standard SUV or 4-wheel drive vehicle whereby it becomes an inexpensive, mobile replacement for the conventional “doghouse”.

SAFE

The SAFE device provides a GPS timestamp for each source timebreak with accuracy within  +/- 1 microsecond of UTC.  This timestamp along with status information provided via the Source Encoder is used to partition the ARUs’ continuously recorded seismic data into seismic field records.

When used in conjunction with the ZLand® Source Coordinator, the SAFE will synchronize the source activation to coincide with the sampling interval employed by the ARUs.

If ZLand® is being used as an in-fill to a conventional system, the SAFE behaves as a passive device detecting the timebreak as it is issued by the master system and internally logging the UTC time for each timebreak – the SAFE is invisible to the conventional system.

DRS

Data Harvester Section – location where the ARUs and HHTs are checked out and checked in. The deployment logs from the HHTs are sent to the Data Harvester Section for loading into the overall inventory and prospect database, thus informing the Data Harvester operator of locations of the individual ARUs and time of deployment – this is the check out function for the ARUs.  If a unit is not sited exactly as planed, the actual deployment location will be logged, and a variance from the pre-plan is noted.

Once the ARUs are retrieved, they are returned to the Data Collection and Charging Rack (DCCR), which is the main component of the Data Harvester Section.  The batteries are recharged and acquired data downloaded – this is the check in function. 

Data Sorter Section

The final product of the ZLand® operation is generated here.  Once all of the pertinent information has been received from the various components, the Data Sorter segments the data contained in the bulk records received from the ARUs into appropriate seismic records.  Field seismic records now can be written to tape, USB drive or other selected recordable medium.