Every organisation has the opportunity to make the right choices in order to contribute to a more sustainable future for us all. The compelling evidence provided by the Intergovernmental Panel on Climate Change (IPCC), in addition to the critical, time-bound United Nations Millennium Development Goals, should be incentive enough for the exploration industry, and society at large, to responsibly take action. Unfortunately, this is not yet the case.
The 3D seismic exploration sector is highly cyclical and correlates closely with the price of oil. The number of 3D vessels in the sector has more than halved during the current downturn. A corresponding environmental benefit of this natural selection is that a large number of old, inefficient tonnage has been scrapped. Unfortunately, in the resulting competitive environment, many companies and industry commentators consider ‘being green’ a costly and unnecessary investment, often quoting their challenges to comply with ‘obligations to all stakeholders’. As a result, few companies implement thorough environmental measures in advance of international policy directives. A proactive approach, however, is critical when considering the inevitable time delay in aligning nearly 200 nations across the globe, all with vastly diverging priorities. Perhaps now, when compelling evidence proves that ‘being green’ can actually be great for business, more companies will adopt a proactive approach.
Part of the challenge for the 3D seismic industry is that a seismic arms race took place over the past three decades, which led to the development of increasingly larger seismic vessels towing more and more streamers in the water. At face value, this evolution reduced the cost of 3D seismic for the oil companies through more efficient acquisition of seismic data (i.e. more square kilometres acquired per unit of time). However, this seismic arms race has inadvertently led to significant environmental, safety and geophysical inefficiencies. Larger vessels meant increased displacement (resistance through the water) and thus more energy consumption required to propel these ships through the water. Towing more streamers meant that the offshore seismic crews had to maintain more equipment, leading to significantly increased exposure to hazards for people working on the back deck of vessels, and in the small boats deployed to carry out equipment maintenance in the water. In addition, the increased number of streamers (corresponding to the width of the seismic array) reduced the geophysical integrity of data on the outer streamers when used in combination with traditional seismic sources in certain geological settings. A tipping point had been reached where bigger was no longer better.
Focusing on optimising the geophysical integrity of seismic data has led to the introduction of multiple array seismic sources to improve seismic data cross-line spatial sampling. A conventional towed streamer seismic source comprises only two arrays, whereas multi-source configuration provides three or more arrays. Developments in continuous recording systems and seismic data processing have allowed more arrays to be added and overlapping source records to be acquired, improving not only cross-line data sampling but also in-line data sampling. The energy from these overlapping source records can be de-blended during data processing, producing a discrete recording for each source. The result of this multi-source acquisition technique is that the increased number of arrays, in combination with fewer seismic streamers towed further apart, delivers a 3D seismic acquisition footprint that enables substantially higher productivity whilst maintaining data quality.
By simply adding one more array to a conventional seismic source, the same data quality and project efficiency can be achieved with 12 streamers towed 150m apart as that obtained with a conventional source configuration with 18 streamers towed 100m apart.
The benefits of a reduced number of streamers in the water are obvious: less drag on the seismic vessel, resulting in less fuel consumption and associated emissions to air; less capital investment associated with streamer equipment; lower costs resulting from the more efficient vessel; and reduced safety exposure for 3D seismic field crews. The multi-source revolution has therefore enabled seismic operators to realise significant operational efficiency gains and reduce the overall safety risks for onboard personnel, while delivering high quality 3D seismic data to clients.
This innovative seismic acquisition technique has now also proved its positive effect on the environment. During the second quarter of 2017, approximately 60% of Polarcus projects were acquired using a multi-source configuration called XArray™ and the quarterly reporting of the company’s emissions showcased the positive environmental effects. As a direct result of acquiring more seismic data per sail line, a decrease of CO2 emissions of about 10% per common mid-point was recorded.
Not All Emissions Are the Same
Discussions about gaseous emissions often revolve around carbon dioxide (CO2) and the amount of carbon that is being emitted into our atmosphere. Carbon dioxide is an easy gas to quantify and compare against, and therefore acts as a useful reference point. However, according to the IPCC there are far bigger threats to our global environment than CO2. The IPCC has established the Global Warming Potential (GWP) to allow comparisons of the global warming impact of different gases. The GWP is a measure of how much energy the emissions of 1 ton of gas will absorb over a given period, relative to the emissions of 1 ton of carbon dioxide. The larger the GWP, the more that gas warms the Earth when compared to CO2.
Based on this research we now know that nitrous oxides (NOx) have a GWP of almost 300 times that of CO2, making them much more damaging gases than carbon dioxide in relation to global warming.
But the most toxic gas of them all is less well-known. Sulphur oxides (SOx) contribute to the formation of acid rain and have approximately 400 times the environmental impact of CO2. In recent years, the International Maritime Organisation (IMO) has implemented stringent regulations to limit sulphur emissions from vessel-operating companies in Emission Controlled Areas (ECA) to 0.1%. However, global limits are still at 3.5%, which encourages vessel-operating companies to continue to operate using the dirtier energy sources such as Heavy Fuel Oil (HFO) instead of the more efficient and environmentally-friendly alternative, Marine Gas Oil (MGO).
As the oil price has deteriorated along with E&P companies’ exploration budgets, reducing operational cost has become a key focal point. At face value, HFO is significantly cheaper than low-sulphur MGO so it is challenging for vessel operators to accept responsibility and choose an alternative, responsible fuel option that causes significantly less damage to the environment than HFO. However, the actual financial benefit of cheaper HFO needs to be offset against realities such as the large and inefficient platforms that HFO is typically used to fuel, or the real cost of transporting and transferring HFO offshore and of heating and treating HFO onboard vessels.
While maintaining the lowest operating cost in the 3D seismic industry, Polarcus’s gaseous emissions continue to fall significantly below regulatory requirements and international Industry Issues averages of other companies. Enabling this superior combination of financial and environmental performance is a result of key initiatives that focus on geophysical and operational efficiency and the implementation of drag reduction across the entire fleet, in combination with Polarcus’s commitment to low-sulphur MGO. By using MGO fuel, an average sulphur content of 0.1% was achieved across all operations in 2016, including fleet support vessels. This weighs in at 25 times lower than other companies in the industry and significantly below IMO regulations, even within ECAs.
significantly below IMO regulations, even within ECAs. The new regulations that the IMO is implementing, such as limiting the global fuel sulphur content levels to 0.5%, designating new ECAs with fuel sulphur content limits of 0.1% and banning the use of HFO in the Arctic, are a clear indication that environmental sustainability is gradually taking a front seat. We invite the rest of the industry to work towards a more sustainable future.