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Oilfield Technology
August
2015
Earlyadoptionof lithium-ionbatterytechnology
for seismicexplorationapplications
Oil and gas exploration is critical for discovering the much needed
petroleum and natural gas used for powering vehicles and
warming homes. Exploration methods vary depending on whether
conducted onshore or offshore, but one thing that remains
constant is that batteries play a role in powering devices used on
land or in the water to record, monitor and communicate data.
Many years ago, geologists interpreted surface features,
surface rock and soil types, or small core samples obtained by
shallow drilling. Modern oil geologists also examine surface
rocks and terrain, with the additional help of satellite images.
However, they also use a variety of other methods to find oil.
Some use sensitive gravity meters to measure tiny changes in
the Earth’s gravitational field that could indicate flowing oil, as
well as sensitive magnetometers to measure tiny changes in the
Earth’s magnetic field caused by flowing oil. They can also detect
the ‘smell’ of hydrocarbons using sensitive electronic sensors
called sniffers. Finally, and most commonly, they use seismology,
creating shock waves that pass through hidden rock layers and
interpreting the waves that are reflected back to the surface
(Crice, 2011).
In seismic surveys, a shockwave is created by the following:
Ì
Ì
Compressed-air gun: shoots pulses of air into the water
(offshore).
Ì
Ì
Thumper truck: slams heavy plates into the ground
(onshore).
Ì
Ì
Explosives: detonated after being drilled into the ground
(onshore) or thrown overboard (offshore).
The shockwaves travel beneath the surface of the Earth and are
reflected back by the various rock layers. The reflections travel at
different speeds depending upon the type or density of rock layers
through which they must pass. Sensitivemicrophones or vibration
detectors detect the reflections of the shock waves - hydrophones
over water, seismometers over land. Seismologists interpret the
readings for signs of oil and gas traps (Figures 1 & 2), (Crice, 2011).
For many years, exploration equipment such as seismic
measurement devices have used batteries to power their
electronics and store data. The initial recording systems utilised
wired recorders requiring miles of cable spread over large regions
of land designated to be mapped. Multiple large sealed lead acid
batteries are used to power arrays of recorders spread over the
land in wired systems (Figure 3). While effective, large lead acid
batteries and cables are heavy and can be difficult to carry and
deploy, and also require large amounts of space to store and
transport. Today many exploration companies have moved to
and/or augmented their cabled systems with Li-ion batteries and
wireless seismic recording systems (Crice, 2011).
Li-ion batteries offer higher energy density as compared to
SLA batteries, which results in smaller size and lower weight.
Imagine the work and logistics required to store and move
thousands of heavy lead acid batteries from site to site; the
human effort needed would be very taxing, not to mention costly.
A Lithium-ion battery of similar capacity could reduce the weight
of each unit to approximately a third of a comparable SLA battery
approach. Additionally, air drops that are weight dependent
benefit greatly by the reduced weight.
Lithium-ionadvantage
First, why is Li-ion so promising when compared to technologies
like nickel metal hydride, nickel cadmium (NiCad) and SLA which,
at one point, were the ‘hot’ technologies? Lithium-ion chemistry
Figure 1.
Seismic dataacquisition ina land setting. (ge0physicsrocks, 2011).
Figure 2.
Seismicdataacquisitioninamarinesetting.(MarineSeismicMethods,2011).
Figure 3.
Thousands of wired systemswill need to be transported to conduct
seismic survey.
Figure 4.
Energy density chart.
