Land Seismic and Why Inertial?

 
Surveying in canopy/forest and urban canyon areas for land seismic acquisition.

In many active geographical regions of land seismic exploration the canopy (trees/forestation) is such that RTK GPS cannot be used for the precise installation of survey stakes. The high-frequency radio signals from the satellite segment of the GPS system (1.2 to 1.6 Ghz) cannot penetrate through the vegetation to the receivers being carried by the field surveyors.

Various optical survey techniques have been tried in the past, to overcome the lack of GPS signals in these environments. Conventional (optical) techniques are primarily used when the canopy/terrain limits GPS operations.

This optical survey technique requires extensive cutting/clearing to allow access for the survey crews and “line of sight" for the surveyors to operate. This cutting takes significant time and causes some impact in the surveyed areas due to the removal of vegetation. The cost of slow production of conventional survey crews can be overwhelmingly improved upon through the use of Zupt’s inertial survey capabilities. One inertial survey crew can deliver the production of two or three conventional crews.

Zupt’s inertial solutions only require minimal cutting/cleaning to allow access. These systems deliver exceptional productivity and quality. Zupt can deliver if low impact surveying is a requirement on your job.

Highly productive inertial land survey for seismic staking: 

Inertial surveying replaces conventional survey crews with unprecedented daily production. We also increase the production over RTK crews in areas of sparse canopy as we can complete the work in a single pass. Our operations always result in “low impact” cutting.

Inertial surveyors are Your Drillers Best Friend

Inertial operators are experienced in the best use of inertial technology in oil exploration. The production achievable from our inertial systems demands a very close working relationship between field cutting crews, clients drilling crews, your surveyors and the eventually the Zupt support group. Our personnel fully understand the concerns and issues associated with access and drilling/shooting productivity.

Inertial surveyors will survey and provide access with the drillers’ productivity in mind.

Optimal cutting = low impact + high productivity

Receiver lines: The conventional requirements for perfectly straight and clear-cut receiver lines, geophone spacing and cable limitations, still exist for your inertial operations. If the occasional tree or shrub can be worked around without removing it, you can leave it in place and keep producing. A large path will be cut for easy access down the line.  

Because you do not need line of sight you can leave these occasional obstacles causing a very slight offsets (20cm or less) for the phone lines, benefiting everyone while not affecting the juggies and their ability to be productive - less cutting leading to less safety issues, less environmental issues, time saved... You cut very straight receiver lines and you optimize production while delivering high quality survey.

Shot Lines: We understand the primary need for high production drilling crews. A clear, well-flagged line with easy access, appropriately cut is the primary focus when working on offset or in-line shot lines. Your inertial operators will ensure that drillers find the shot point quickly, and their drills can progress quickly (safely) from shot point to shot point: good access, good flagging. The same logic works for the shooters when time is truly of the essence.

And this means? … a Driller and Shooter Friendly Survey 

Inertial lines will give drillers far better access than conventional crews. The slightly winding, well flagged path can move around thick bush and give the drilling hardware easier access on manageable slopes. This is to be compared with conventional (theodolite) surveying techniques that can often lead to impossible slopes, cut trees on the path and dangerous drilling conditions, just because the line had to be cut perfectly straight due to the line of sight limitation (and only for that reason).

With optical surveys, drillers often need to move the shot point a few feet away from the installed stake for access reasons: the stake is placed by a fence, under a tree, on a berm or a ditch making it impossible to drill. This action driller moving the stake is detrimental to the overall accuracy of the seismic project, and is rarely noticed. The drillers re-located drill point is rarely resurveyed.

By using “driller friendly” inertial surveyors on your project, the shot point will be placed and surveyed in the right location - within offset specifications - for the driller to feel comfortable drilling. This type of surveying will also improve your drilling safety. Because our surveyors can avoid the very difficult vegetation exactly like the drillers, they create a path of least resistance - and less damage to the environment - that is many times more productive for the drillers and also for the shooters, therefore the path of best production for the crew.

We understand that an intelligent and knowledgeable inertial survey team can significantly improve safety and seismic production.

Survey control 

The inertial surveyor can undertake the installation of control to ensure optimal production for his inertial units. This control network will usually be established through triangulation, traversing or GPS: post-processed GPS for the first order network and possibly RTK GPS for example for second or third order.

A good average value is 1 Control point every mile (1.6km) of straight line for seismic.

Operational quality indicators 

Inertial zero velocity update drift control and error (rms from Kalman co-variance matrix diagonals) analysis is available for our units during operations to ensure quality control of all installed locations. Immediate QC is available at ties made throughout our daily operations.

Field proven hardware and software 

Zupt’s land seismic inertial systems are constructed with state of the art inertial measurement units (IMUs) with customized navigation software specifically designed for seismic operations. We even have state of the art custom battery packs specifically designed for our field units to ensure maximum power to weight ratios to minimize the load on our field personnel.