Between the Poles

Advanced geophysical remote sensing rapidly captures high resolution 3D data about subsurface geology

Uncertain knowledge about what lies under the surface is a major cause of delays and budget overruns on construction projects.  It is well known that not knowing the location of utilities and other infrastructure is a major cause of delays, but unforeseen ground conditions; soil conditions, ground water and underlying geology, is also a major cause of large budget overruns on construction projects, especially for projects involving deep excavation and construction below the seabed.  Advanced remote sensing, 3D digital ground modeling and visualization technologies are changing dramatically how we capture, analyze, visualize and share information about the subsurface.

Background 

Every construction project devotes considerable effort to discovering subsurface geotechnical conditions and structural geological setting.  The traditional approach involves boreholes, CPT and test pits. Regardless of the process, all geotechnical acquisition results in point data.  This data is used by the engineering consultant for a single project and rarely shared. 

In the Netherlands an attempt is being made to address the problem by the Key Registry for the Subsurface (BRO) which came into force in January, 2018. The BRO registry ultimately will record 26 geotechnical data types. In the UK the Dig to Share project, supported by Atkins, the British Geological Survey (BGS) and Morgan Sindall, is also attempting to address this problem. Its aim is to develop a fully digital workflow, which is accessible to the whole industry, to upload and access data from a web-based system.

The traditional approach to data collection about the structural geological setting involves shallow seismic reflection, seismic refraction, and legacy resistivity methods.  These methods provide information about the different layers underlying a site though not always as accurate as required. Typically, this type of data is low resolution, and will usually not be useful in defining key sub-bottom variations such as the transition between compacted sands and rock, vertical features or variations in rock strengths across a site. In addition, legacy qualitative methods rarely provide the quality and accuracy to generate reliable and useful high-resolution models of the variations in each stratum across a site.

Three-dimensional geological modeling has developed dramatically over the past 30 years from contouring and gridding techniques using mainframe computers through to PC based geological modeling software. These tools were developed for certain industries such as mining and oil and gas and deal with very specific geological scenarios and data types. Many geological survey organizations worldwide have started to implement varying software systems and methodologies to facilitate a migration, from a 2D paper-based survey to a 3D digital service provider of geoscientific information. Rapid advances in gaming technology has enabled a renaissance in ground modelling and particularly in 3D visualizations.

Advanced remote sensing technologies

Another approach relies on remote sensing technologies that are designed to acquire large volumes of high-resolution data about the structural geology over a large area, quickly.  These advanced geophysical methods are digital and allow for determination of thickness and depth of geological layers as well as layer and intra-layer information from the one sensor. Shot intervals are better than one per second make it possible to collect large volumes of high-resolution data in a short period of time. The objective is to understand subsurface complexities in detail at a site which makes it possible to target boreholes to elucidate geological anomalies.  I had the opportunity to talk to Jason Errey, Director OEMG Global, about one of these advanced technologies.

High resolution resistivity technology

One such method is Aquares, an advanced resistivity technology which enables the capture of high resolution quantitative and qualitative information about the strata under a site. Quantitative data includes depth and thicknesses of sub-bottom structures. Qualitative data includes type of sediment; sand, silt or clay and rock characteristics such as fresh or weathered. High resolution combined quantitative and qualitative data is extremely useful for successful planning construction activities including, dredging, trenching, under bores, tunneling, or piling. With this information project planners and engineers have a complete picture of the existing subsurface environment. This allows designs to take into account subsurface structures such as weathered and unweathered rock outcrops or buried river valleys to considerably reduced dredging and construction costs.

Modern digital ground modelling practice is essential for planning and asset management. The results of high resolution Aquares surveys can be combined with other data in an Integrated Digital Ground Model (IDGM) via the MyGeoTwin product. Data is acquired for the IDGM in a staged manner and stored in a data lake for use in future projects.

Vertical cross section of Sydney Harbour

Sydney Harbour Metro tunnel

An example of where the Aquares high resolution resistivity technology was deployed is the Metro tunnel under the Sydney harbour in Australia.  In late 2016, Sydney Metro commissioned an Aquares advanced geophysical survey. The Aquares survey was undertaken in two stages over two nights. On the first night a high-resolution survey targeted the top 15 metres below seabed.  On the second night the survey extended this to a further 40 metres below seabed. A week after acquisition, a four-dimensional model covering the top 40 metres below seabed comprising one million data points was delivered to the Sydney Metro Authority.  When compared to the legacy below seabed information, the new geophysical information showed substantial differences in the rock levels in addition to previously undetected remnants of a river channel following a geological fault line.

Vertical geological section of Sydney. Aquares resistivity survey data has been inserted into the project IDGM allowing vertical sections to be exported to GIS/CAD, Google Earth, Augmented Reality and holographics.

The new technology is also more efficient.  For the initial design for the tunnel created in 2015 two years was spent conducting and analyzing multiple legacy geotechnical and geophysical surveys, costing millions of dollars. Due to site complexities, these early surveys failed to define the correct rock level and the associated geological risks. The Aquares survey was completed in 2 nights, processed in a week and combined with all other available data in a 4D ground model a week after that, at a fraction of the cost.

Buenaventura dredging

The Port Authority in Buenaventura needed to undertake maintenance and capital dredging along a 10 km section of a 180 m wide channel leading to the port. Based on limited seismic results that were unable to identify intra-layer variability and five boreholes, dredging contractors assumed approximately 30% sediment and 70% hard rock and estimated an average dredge cost of $17.6 per cubic metre.

The results of a more advanced Aquares geophysical survey method provided crucial information about the level of the sediment-rock interface and the differentiation of harder and softer rock types.   The survey found that the channel bottom was composed of 70% soft sediments, 25% rock and only 5% hard rock. As a result, cost estimates were lowered to $7.9 per cubic metre. For the dredge volumes on this particular 10 km section of the access channel, the cost savings were estimated at $34 million.

Conclusion

Modern digital ground modelling practice is essential for planning and asset management. Advanced remote sensing, digital data acquisition and management tools now available reduce the risk of unforeseen geological conditions delaying and significantly increasing the cost of major construction projects. Advanced digital geophysics provides a reliable source of 3D data that can be integrated into an integrated ground model to provide asset owners with a digital tool to manage and control risks relating to subsurface ground conditions.

Growing gap in electric power infrastructure investment in the U.S. will decrease reliability and resilience of the grid

Last week the American Society of Civil Engineers (ASCE) released a new report in the Failure to Act series "Electric Infrastructure Investment Gaps in a Rapidly Changing Environment" that estimates the investment gap through 2039 for electric power infrastructure in the U.S. and assesses the impact of under investment in electric power infrastructure on the U.S. economy.  Modern economies are increasingly dependent on "chip technologies" powered by electricity. Recent projections suggest that ICT consumption of electricity could reach over 20% of total demand by 2030 with data centres consuming over a third of that.  It is estimated that the average cost of an outage at a data centre is about $8,851 for every minute the electricity grid is disrupted,

Background

Just about everything that we use daily from phones and the internet to water and wastewater rely on electric power. In addition as we reduce the carbon footprint of the economy, electric power becomes increasingly important because in most jurisdictions electric power has a low or decreasing carbon footprint compared to other sources of energy.

The U.S. electric power grid is composed of the bulk power system including large-scale generation facilities and the transmission network. 10,000 power plants comprise the generation capacity of the U.S., not including residential solar panels or small-scale wind farms.  More than 600,000 circuit miles of transmission lines, of which 240,000 are high-voltage, carry power from generation plants to the distribution nrtworks. An estimated 5.5 million miles of local distribution lines (including underground cables) carry the power to end users.

Increased ICT consumption of electricity

One of the sectors that is projected to consume an increasing share of the U.S. electricity supply is information and communications technology (ICT).  Currently it is estimated that the share of electric power consumption by ICT is between 5 and 9% of total power demand. Currently  ICT’s electricity consumption has plateaued.  Increasing load from growing Internet traffic and chip technologies has been balanced by increased efficiencies. But this may change in the next few years. Forecasts suggest that the total electricity demand by information and communications technology (ICT) will accelerate and that of the ICT pie data centres will take a larger slice. The chart shows an "expected case" projection which shows that ICT consumption of electricity could reach over 20% of total demand by 2030.  ICT requires a reliable and resilient power grid and will be one of the most important drivers to address the gap in investment in electric power.

A related aspect of the U.S. economy is a structural shift away from energy intensive industries such as heavy manufacturing. A measure of this is energy intensity which is the amount of energy that is required to produce one dollar of GDP.  In 1980 12,100 BTUs were required to create one dollar of GDP.  By 2014 this had declined to 6,100 BTUs per dollar. About 40 percent of the improvement in energy intensity was attributed to structural shifts, and the remainder to improved efficiency.

Gap in investment in electric power

Over the period 2011-2020 demand growth estimated at about 8% has been net with increased generation capacity. But for the period 2021-2040 the report projects increasing divergence between demand and capacity. If current trends are projected into the future the U.S. is facing a $208 billion (in 2019 dollars) shortfall by 2029 and a $338 billion shortfall by 2039 in what is needed to ensure a reliable energy system.  Most of this shortfall is attributed to under investment in generation and transmission. For transmission the largest challenge is not so much attracting investment in transmission, but that regulatory approval from all levels of government averages about 10 years for a new transmission line and can amount to 50% of the cost. Unlike Germany where the Bundesnetzagentur has national authority over long distance transmission lines, for bringing wind power from the North Sea to the south, for example, in the U.S. states are the top level regulatory authorities for transmission lines and a rule of thumb that has emerged is that to build a transmission line as rapidly as possible, don't cross state boundaries.  The demand for new transmission is exacerbated by the growing sources of renewable energy generation in the West that require new transmission lines to bring the power to the East and the Pacific Coast.

Impact on the economy

For consumers electricity system outages, voltage surges, and brownouts represent a direct cost to their households and businesses, and indirectly through impacts on the national economy. It is estimates that the cost to residential customers from each electric interruption event was $6.68 (2018 dollars).   This is about twice as high as it was five years earlier partly because or our increasing reliance on chip technologies in out daily lives.

When the grid fails businesses experience downtime, lost labour and productivity.  The report found that outages have the biggest impact in the manufacturing sector, costing almost $42,000 per event on average in 2008. As a result of the growing importance of ICT, data centres have become essential for many different industries. It is estimated that the average cost of an outage for a data centre increased from $505,000 in 2010 to $740,000 in 2016, or about $8,851 for every minute the electricity grid is disrupted.

Furthermore, disruptions to the grid add to costs and can result in U.S. manufactured products becoming less competitive in international markets. Between 2020 and 2039, it is estimated that the gap in investment in electric power will result in the loss of $271 billion in the value of U.S. exports.  In addition businesses and households will have to pay an additional $142 billion for foreign imports.

Satellite able to measure methane emissions from individual facilities launched

Last night, September 2 at 11:51 p.m. EDT at the Arianespace satellite launch base in Kourou, French Guiana (UTC-3) the VV16 mission launched 53 satellites, ranging in weight from 145 kg to 7 kg.  Among them was GHGSAT-C1 or "Iris", a 16 kg Canadian satellite that detects methane emissions from specific facilities at high resolution.

Background

Source Nature 14 July 2020

Annual emissions of methane (CH4) have risen by almost 10% in the past two decades primarily resulting from emissions from the oil and gas industry and livestock. A recent Environmental Defense Fund (EDF) study concluded that methane emissions from the U.S. oil and natural gas supply chain in 2015 amounted to about 2.3% of gross U.S. gas production and are about 60% higher than EPA estimates.

A 2016 study found that just a few natural gas wells account for more than half of the total volume of leaked methane gas in the United States. An extensive aerial infrared camera survey of 8000 production sites in seven U.S. oil and gas basins found that 4% of surveyed sites had one or more observable methane high-rate emission plumes. Furthermore the large variability in methane emissions for similar equipment and facilities in different geographies supports the hypothesis that equipment malfunction is a major source of emissions. To identify the sources of methane emissions oil and gas companies are increasingly attempting to detect and monitor emissions from their facilities including oil and gas wells, tank farms, and compressor stations.

An additional important business driver is the global carbon market which is currently estimated to be about $50B and growing. This provides a financial motivation for industrial emitters to measure and manage their emissions.

Until recently methane emissions have been measured on the ground in a a slow, laborious process using a hand-held scanner. Government-funded aircraft overflights or satellites have captured emissions over broad areas but with insufficient resolution to identify individual facilities as sources.

Satellite-based methane emissions measurement

In 2016 a privately-funded startup GHGSat launched a proof-of-concept cubesat named "Claire" weighing 15 kg to measure methane emissions from individual oil and gas wells, refineries, compressor stations, landfills, animal feedlots, rice paddies, and natural sources. The objective was to provide a satellite-based methane measuring device that would enable private industry to estimate emissions from its own facilities anywhere in the world. About the size of a microwave oven Claire orbits the Earth every 90 minutes. Its field of view is 12 km x 12 km and it has a spatial resolution of about 50 metres. Claire is able to measure emissions from over 1,000 sites per year.  The GHGSat-C1 or "Iris" satellite that was just launched has higher resolution (25 metres) and will be able to measure emissions much more rapidly with a 10x performance improvement compared to Claire.