Seismic Surveying


Seismic Surveys


Seismic exploration is the crucial tool in discovering new sources of oil and gas. It is used to create graphic representations of the earth’s subsurface geologic structure, which allow exploration companies to accurately and cost-effectively evaluate an area for its oil and gas yielding potential.

On-shore survey areas often cover thousands of square kilometers. At the heart of their systems are huge networks of thousands of highly sensitive seismic sensor nodes. These networks of sensors sit on the surface of the area to be surveyed and capture data from the ground below that is subsequently processed into imagery. These images are then interrogated to see where pockets of oil or gas could be located, before any test drilling commences.

Illustration of the seismic imaging process. A vibrator truck excites the ground generating acoustic waves. These waves reflect off the various ground layers and are recorded by the network of sensors on the surface.

Illustration of the seismic imaging process. A vibrator truck excites the ground generating acoustic waves. These waves reflect off the various ground layers and are recorded by the network of sensors on the surface.

Today’s standard approach to deploying these networks is to connect each sensor via cables. The sheer amount of cables required is enormous, making deployment and logistics complex, and transport and maintenance expensive.

The increasing demand for more detailed imaging of subterranean structures means that the size of the seismic networks will need to grow enormously – from tens of thousands of sensor nodes to millions. As this happens the logistics around cabled systems will become even more complex, expensive and cumbersome.

The market is developing cable-free solutions to overcome these issues, but is moving slowly. Current products often come with compromises and practical limitations. Nodes can be bulky or accompanied by heavy external batteries making deployment complicated. In lighter-weight units, battery life and recording time can be short, limiting how long units can be in the field and increasing costs associated with deployment. Importantly, scalability of networks, especially those promising real-time data, also appears to be a major challenge.

Innoseis has developed TremorNet, a system that resolves issues with current seismic sensing networks and anticipates what the market will need over the coming years. TremorNet is smaller and easier to handle than other systems. Its ultra-low power electronics and patented low-power communications protocol mean that each sensor has much lower power requirements – around a tenth of the power consumption of current best competitors. This in turn means there is no need for heavy batteries or additional equipment in the field. The result is a network that is much easier to deploy, which reduces health and safety exposure as well as personnel and transport costs associated with deployment.

TremorNet

TremorNet is also designed to easily scale up to million node networks. The trend in seismic surveying is to deploy more nodes per km2 which increases the density and quality of geologic imaging. This technique ensures that pockets of oil and gas are more often detected, increasing the overall efficiency of exploration and production spend. Some industry participants predict that million node networks will be required in the next decade as both the density of nodes and size of survey areas increases. If this is the case, cabled solutions will scale with great difficulty and cost, while current wireless solutions will fail because of short recording times and ineffective network architecture.