• With its true all-azimuth capability, Z3000 already has proven its merits  - in a high-profile field application at Atlantis Field in the Gulf of Mexico - for superior quality data gathering to image beneath salt bodies, which are infamous for distorting the seismic signal. These salt obstructions are widespread, particularly in the deep water Gulf of Mexico.

• 4-D, or time-lapse, seismic, which is becoming increasingly necessary for effective reservoir monitoring and management, is a natural for Z3000 application in deep-water fields. Every node survey is also a by-product 4-D survey because of positional accuracy and repeatability. In fact, positional accuracy better than 3 meters on average, in itself, ensures 4-D capability.

• Enhanced oil recovery (EOR) goes hand-in-hand with 4-D as a niche target for Z3000 application. For example, once a material is injected into the reservoir, it’s essential to see the path it traverses.

• Infill areas are an ideal site for Z3000 technology. Platforms often are placed over the very heart of a field, and acquisition of seismic data around the field with streamers fails to address the void area. Node placement in this area allows the streamer vessels to simultaneously record both streamer and node data, which  can be merged in processing so the field is geophysically transparent. The infill part of the survey automatically becomes a 4-D survey due to positional accuracy.

• Because the Z3000 nodal units each have a hydrophone and three geophones, the nodes are inherently multi-component, or 4-C, capable. Since they can record the converted wave, they have the ability to see through gas clouds in the many deep-water fields where these gas clouds make it near-impossible to illuminate the geology using conventional seismic acquisition methodology. 

Atlantis Field Project in Gulf of Mexico Proves Z3000 Commercial Viability

In March, 2006, FairfieldNodal and BP completed a deep-water ocean bottom node (OBN) technology program begun in October, 2005, using the Z3000 system at the BP-operated Atlantis Field in the deep-water Gulf of Mexico. The primary motivation for the project was to gather wide azimuth seismic data that would lead to improved illumination of subsalt structures, which have long been problematic for geoscientists. The data acquired are excellent quality, and BP currently is preparing to reveal the initial images acquired via in-house processing. The “at-scale” Atlantis field trial was an unprecedented nodal implementation in both scope and depth. In fact, it entailed deployment – and retrieval – of nodes coupled to the seabed at 1,628 locations spread out over 240 kilometers at water depths between 1,400 and 2,200 meters. The scale of the project was determined to ensure acquisition of a data set that would be useful in the commercial development of the field rather than just providing a snapshot look.

It is noteworthy not only that the nodes were recovered from all 1,628 locations but that positional accuracy was determined to be better than 3 meters on average – an impressive accomplishment in these water depths. This becomes still more extraordinary when considering a part of the survey had 2,000 feet of scarp slope, with gradients up to 30 degrees plus, making it difficult to find locations on the slope less than 10 degrees to put receivers down and position them accurately with the ROVs.

In all, myriad expectations for Z3000 system nodal technology in deep water were documented at Atlantis, including:

• High node reliability allows confident “blind” sourcing.
• High relative positioning accuracy enables node deployment and recovery within a few meters.
• Nodes can be readily deployed and recovered around complex subsea installations.
• Challenging ocean floor terrain and slopes can be managed effectively.
• Negligible environmental impact.

Successful Z3000 Program at Deimos Field in Gulf of Mexico Follows Atlantis Accomplishment

Following the successful outcome of the Atlantis program, FairfieldNodal moved quickly to implement the Z3000 technology in a project for Shell at its Deimos Field in approximately 1,000 meters of water in the Gulf of Mexico’s Mississippi Canyon area. 

The Deimos survey required about 80 days from mobilization to demobilization and covered close to 134 square kilometers. Node spacing was approximately 400 meters with a 50 meter source line separation and 50 meter source separation (25m flip flop). The less-than-two-percent dropout rate on the nodes deployed is valid testimony to the success of the survey.

Z700 Acquisition Animation                               Z700 Product Information

Exceptional Reliability, Dramatic Cost Reduction (0 - 700m water depth)

Like its deep-water counterpart, Z700 – rated to 700 meters water depth – is comprised of autonomous nodes, each with a state-of-the-art lithium battery and exceptionally accurate clock. The nodes constantly record sound waves coming from the source vessel at the surface until they are retrieved to download the data, which are subjected to QC while the batteries are being charged for re-deployment. The reliability of contemporary electronics positions this type technology light years ahead of massive and bulky, wire-filled cables commonly used for data collection.

In yet another nod to its deep-water mate, Z700 requires about half the crew members of a conventional OBC shoot and only two vessels: the node management vessel and a dual source shooting vessel. Fewer boats in the water mean significantly fewer potential problems, which provides both an operational and financial edge. But this tells only part of the story of the economic advantage Z700 brings to the table. For instance, a greater than 40 percent vessel cost reduction with a Z700 crew vs. a conventional OBC crew offers a compelling incentive to deploy this unique system. Because the sole node handling vessel has no physical connection to the receiver spread on the sea floor, it does not need to be a dynamically positioned vessel, which is the highly expensive type boat required with conventional OBC. This contributes impressively to conservation of capital.

Z700 provides a ready solution to conventional OBC problems. The autonomous nodes are deployed via simple, high-tensile strength rope, negating the need for any type of stiff, awkward cable which typically creates myriad problems when working in shallow waters commonly congested with varied infrastructure. Complications such as cable leakage and the oft-failing in-water cable connectors are now a thing of the past - you can say goodbye to troubleshooting. Numerous field trials led to the design of this absolutely reliable nodal system, which provides superior data and speedier operations than OBC.