Go-CQuest 2 CRUST
Introduction
In order to achieve net zero emissions (NZE) and more importantly for humans the need for negative emissions (NGE), carbon capture reduction use transport and storage (CRUST) or just CCUS/CCS are necessary according to both the IPCC Special Report (SR:1.5%oC[1]) & IEA[2] Sustainable Development Scenario (SDS) for long-term large-scale material carbon abatement by geosequestration (Go-CQW).
CCS into CRUST
The first stage in determining natural CCS geosequestration reservoirs/sinks/geo-tanks is to initially conduct seismic surveying of sedimentary basins of interest. In most cases where extensive surveys have already been conducted over many decades, usually in the pursuit of oil and gas (O&G), it makes sense to focus on those areas where the evidence already exists. Unfortunately for most of the world outside the known major O&G production areas the detailed work needed is insufficient, which is most of the planet outside on/offshore of North America, North Sea, Middle East, West Africa (Nigeria-Congo), Brazil, Australia and bordering the southern South China Sea. However, other than reusing existing offshore infrastructure, the use of new onshore wells, pipelines and central hubs makes economic sense, as the development of new offshore facilities is generally a factor of ten times more expensive and the marine environment is much more unforgiving to operate in.
Other than O&G exploration, substantial work has also been done on onshore hydro-geology in order to define suitable water aquifers, but generally not to the same degree as O&G delineated areas. However, in Australia, for example, and Queensland in particular, thanks to the development of coal seam (bed methane) gas (CSG/CBM) and tight regulatory protection for aquifers, the Great Artesian Basin (a complex of overlapping basins) has, as one of the worlds’ largest basins, been extensively surveyed. As a hydro-carbon geologist, involved in assessing groundwater aquifers and petroleum reservoirs from both a resource delineation and an environmental protection perspective, who has now come full circle from exploration to protection, realises that the inter-connectedness of these sedimentary sequences and their future prosperity is in now moving from extraction to injection via CCS while indirectly recharging the whole basins production.
By injecting CO2[3] into, for example, the base of the Surat Basin into the base of the Precipice sandstone aquifer, at 2.5km below the surface, with its maximum capacity of up to 10km radius from the injection point, it will build pressure up to 100km from the injection point, and potentially the whole basin with overlapping injection points circles-of-influence. Initially this could be seen as a form of enhanced oil-gas-water recovery (EOR-EOG-EOW) a potential indirect-benefit basin wide. Of course, many would say this is a bad thing continuing the extraction of fossil fuels, however the benefit, as in the US with their tax credit (45Q), during the transition from O&G use, incentivises CCS. However, this is not the same as the traditional use of injected CO2 to enhance oil reservoirs as the CO2 becomes not only a solvent but more importantly displaces fluids toward another pumping well. Note: EOR/EOG is not eligible for Australian Carbon Credit Unit (ACCU) per tonne of CO2e stored.
Without a market-based-mechanism such as a carbon price/credit, the only alternative is for government, and therefore taxpayers, to foot the bill, rather than encourage the carbon market to accelerate all avenues for CCS. However, a carbon market needs to be better regulated than the Australian water market and not end up being controlled and gambled away by wealthy big players.
Australia has a requirement for offsetting environments impacted by mining (including O&G) whereby the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) Environmental Offsets Policy (EOP) for significant/residual environmental impacts, are regulated and therefore excluded, but could be considered as carbon offsets and thereby also receive, under the Carbon Credit (Carbon Farming Initiative) Act 2011, however, this is only temporary CCS as it is a depleting sink as droughts and bushfires accelerate with climate change. However, there is currently insufficient funding for Bio-CCS to replant trees or enhance soils, and thereby use natural ecological disaster risk reduction (ecoDRR) practices let alone reduce global warming. As an example, where coastal mangroves were intact, they provided protection against the South East Asian tsunami, and trees provide many other benefits to communities, e.g., shade in cities, slow flows and capture sediments, stabilise slopes, retain soil moisture and lower water tables thereby controlling salinity. Note: All CCS options must be used and accelerated simultaneously as there are no carbon bullets.
Although the use of hot rocks in Australia’s outback has been unsuccessful mainly due to re-injected water leaking from too many unknown and improperly sealed well bores the use of geothermal energy could benefit from using CO2 where water is in short supply or being over pumped by unsustainable drawdown practices. However, if the hot rocks are basaltic, reactions of the carbonated water and its minerals (≤25% Ca, Mg & Fe) produces new rock, sealing fractures and geosequestering carbon thereby potentially negating potential geothermal power output.
When we look at modern environments, such as geothermal areas, we find the existence of extremophile bacteria that thrive in, as the name suggests, extreme environments e.g., acido-thio-bacillus ferro-oxidans an acidic iron-sulfide bacteria with the potential to create sulfuric acid (H2SO4) in acid sulphate soils (ASS) or acid mine/rock drainage (AMD/ARD) once the soil/rock is exposed to air. These bugs, like many others are the precursor that enabled the development and deposition of mineral resources e.g., fossil fuels. However, the biggest impact for the development of CCS infrastructure is the impact on concrete and steel infrastructure by corrosion, e.g., pipelines crossing from land to marine environments such as the pipelines across the Narrows Crossing between the mainland and Curtis Island in Gladstone harbor. Because of this concern a processing area was established to mix any dredged spoil with lime (CaCO3) in order to neutralise the potential for acid development (1m3 of 1% total oxidisable sulphur spoil with specific gravity 2kg/m3 uses 100kg lime). The best way of managing ASS that occurs in pipeline trenches or shipping channels is to dredge from below lowest astronomical tide (<LAT) and keep it wet and dump it below LAT offshore. Pipeline construction must also meet the stringent SAI Global AS/NZS[4] 2885 standards and APPEA[5] Code of Environmental Practice (CoPE). Although after making a submission in 2013 on behalf of WorleyParsons to manage coastal impacts I see that it still has not been included in the CoPE.
The opportunities for Australia’s uptake of CCS are manyfold, including the additional carbon offset of liquified natural gas (LNG) by LNC (CO2) for reinjection, utilisation of economic feedstock conversions for blue hydrogen (H2) that is still more economical in terms of cost, land and better use of renewables, that reduce the diversion of centralised power schemes (solar/wind farms and hydro) output away from public benefit, and keeping grid power prices lower and not subsidising industry.
The benefit to society is the development of new industries, building on existing energy intensive export-oriented sectors such as mineral processing and meeting domestic demand for cement, iron ore and chemicals (NH3[6] for fuel, fertilisers/explosives), thereby enhancing Australian processing of raw materials rather than exporting the benefits to other countries, offsetting Scope 3 GHG emissions (GHGE) and meeting new NDCs at COP[7]26, e.g., 50% ↓CO2e[8] by 2030 and NZE by 2050? Redirecting/ retraining world leading capability in hydro-carbon geology and engineering into new and super critical field of CCS both at home and abroad for increasing CCS demand throughout Asia, where there currently is insufficient knowledge of or potential for suitable geosequestration sites.
Australia could be a repository for CCS that is not available or sufficiently developed in the nearby Asia-Pacific. If ships are designed to take LNG out, they could be modified to bring clean CO2 in. The (UN) International Maritime Organisation’s (IMO) International Convention for the Prevention of Pollution from Ships (MARPOL) applies to all offshore vessels within international waters outside countries exclusive economic zones (200nm[9]), however, all countries use MARPOL as the basis for developing their own legislation within their own maritime territories. The specific International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) forms the basis for constructing gas carriers (tankers) used in any potential construction/conversion of LNG to LNC. Of particular interest is the London (Waste Dumping) Convention (LC) and Protocol (LP) where Annex II was the most advanced international regulatory instrument addressing CCS in sub-sea geological formations (CCS-SSGF)[10]. The Shell JV’s Prelude floating liquefied natural gas (FLNG) facility having produced natural gas off the West Australian coast since mid-2019 demonstrates the ability to build CO2 carriers capable of whole-of-chain processing of CO2 gas and injection into suitable reservoirs offshore in extreme conditions from tropical cyclones/hurricanes/typhoons.
Seismic surveying uses advanced modelling systems, for example Schlumberger’s Petrel 2020, capable of converting seismic waves into extraordinary 3D models of sedimentary sequences many kilometres below the earth’s surface. Seismic surveys use vibration waves generated by ‘hammers’ impacting the land/water surface to create reflections from shallow or refraction from deeper density layers that cause time delays in the return signal to geo/hydrophones at the surface. Surveys can delineate the types of traps and the existence of faults or fractures that may permit loss of CO2.
Whether the proposed sedimentary strata are saline aquifers, as most sequences are due to trapped seawater from marine phases of deposition, or depleted O&G reservoirs, un-mineable coal seams or fractured shale or carbonates, the same stratigraphic traps are critical for all reservoir types. The only trap that in not recommended is where oil has been trapped by a salt diapir, not diaper that only provides small-scale short-term absorption! The salt was compressed upwards into a dome and were once considered for the storage of radioactive waste only to realise that the salt was migrating upwards toward the surface negating long-term storage however, they can still provide short-term storage for CH4[11]/CO2. As long as the faults themselves are not re-activated, as some have been in the USA where insufficient monitoring, maintenance and mandatory oversight seems to be the norm. Unlike the US, the resources ownership in other countries belong not to companies but to the country as a common resource and this may underlie many of the unsustainable practices in the US!
The displacement of non-conductive strata across strata of interest by reverse/normal faulting can still provide permanent seals of reservoirs to restrict fluid flow. It is critical to conduct pressure testing of wells by either open-hole drill stem tests (DST) allowing natural flows to be assessed or by pumping to the likely pressure, which is several orders of magnitude lower than fracking pressure. It is assumed that a fold needs to be synclinal (saucer upside down) rather than anticlinal (saucer right way up), however, if the synclines basin is massive and the strata is virtually horizontal, as in the case of the Surat Basin basal unit, then there is still the potential for large-scale storage providing the CO2 does not migrate beyond the expected reservoir. It is also probable that without pumping pressure and expected reaction of CO2 with minerals within the reservoir the CO2 will be safe for millennia. Of course, monitoring wells and seismic surveys will be used until such time as the ‘tanks’ stabilise.
However, as good as seismic surveys are it still needs interpretation by more definitive information that can only be acquired by drilling down to the zones of interest and in particular collecting core from the potential reservoir trap to the sink. If sufficient O&G exploration work has been conducted in the areas of interest, with a suitable buffer zone away from current oil-gas-water extraction sites, in order to not impact them or allow them to impact the carbon reservoir causing leakage, then this information is critical in testing and developing the reservoirs potential.
Sedimentary basin analysis has been conducted over many decades enabling the understanding of how sediments are deposited to build incredible thicknesses of sediments that under their extreme weight downfold the surface, e.g., syncline, and possibly add to the upfolding margins along with tectonic forces. Underlying all this is the acceptance and use of plate tectonics first introduced by Alfred Wegener a century ago. Using tectonic models, it is now possible to understand the development of massive sedimentary basins that are common to most stable continental floodplains, their coastal deltas and marine shelves. However, overprinting this are changes in sea level due to ice ages that Milutin Milankovitch recognised a century ago from cycles around the sun, and isostasy changes (glacial loading and unloading of land) with related micro-seismicity.
None of this new as all geophysical changes have been modelled in modern climate models, such as tectonic induced earthquakes, faulting and volcanic eruptions, and the known environmental (bio-chemo-spheres) changes resulting. The stable continents have undergone slow geologic change, showing sedimentary sequences dating back to the beginning of life on earth, potentially up to 4-billion-year-old algal traces to almost the formation of the planet itself at 4.5-billion-years old. However, geo-thermo-baro (temperature and pressure: T&P) changes with burial, hydrothermal or tectonic alteration has metamorphically altered sedimentary rocks and eliminated CCS potential.
Knowledge of potential sedimentary sequences of interest for CCS have been gained from the basin margins where outcrops and wells allow direct analysis. By determining the characteristics of the different sedimentary layers, it is possible to build a model of how those layers were developed using the geological uniformitarianism theory that the present is the key to the past and studying analogues or actual examples of the sequences of interest from well logs. For example, different geomorphic environments such as braided river plains create definitive patterns of deposition, described by Facies Models that were originally developed by Roger Walker 40-years ago, to assist in identifying likely environments that exist at time of deposition in comparison to modern equivalents.
In all sediments living things leave traces or fossils (shells) that help us understand the environments in which they were formed, e.g., deeper marine water phytoplankton become micro-fossils, that can survive in drilling fines/cores, and can be dated by comparison with species that have been studied in environments of deposition elsewhere and chronologically placed. Organic lifeforms are also the precursors of all carbon deposits such as peat, coal, oil or gas that form natural shallow biogenic hydrocarbons (swamp/marsh gas) or deeper thermogenic (geo-thermal) developed fossil fuels. The groundwater, as mentioned, can be contaminated by dissolved minerals, mainly in trapped seawater from the time it was part of the marine environment, however most water in the GAB is brackish with relatively low levels of salt thanks to high freshwater influxes; CO2 and H2S gases (hydrogen sulphide) that can form dangerous levels in O&G exploration and CH4 in coal mines. A major concern is the release of fugitive emissions, however recent CSIRO[12] high-tech airborne surveys show the levels of CH4 is higher from cattle, wastewater and natural wetlands than from CSG.
Introducing tracers, such as dye solutions or water injected with safe short-life span (10 days) low output radioactive ceramic sand size beads encapsulating an iron particle exposed to a radioactive source. The use of tracers has been useful for over 50-years to determine the extent of aquifers. The plume of tracers moves with the hydraulic movement of water and can be detected at monitoring wells. This is common practice when determining the movement of contaminants in groundwater systems in order to determine the spread of the plume and how best to intercept, extract and treat. It is useful for monitoring the plumes of CO2 at sites where it is already been reinjected such as in the safe long-term 25-year-old Norwegian Sleipner geosequestration operation in the North Sea.
Facies models are also the key to understanding well drilled rock cores that provide a window into the sub-surface. The different grain sizes, particle size distribution (psd), source rock (provenance) and weathering breakdown and rounding indicate the environment, and entrained lifeforms, in which they were deposited and the potential to either store/sink fluids (sandstone) or stop/trap fluid (mudstone/shale) migration. The cores themselves can be directly tested in NATA[13] accredited labs using mercury injected capillary pressure (MICP) to test the pore space between sand grains and more critically pore connectivity (permeability/transmissivity) and fluid flow (petrophysics). This is as important for managed aquifer recharge using water as it is to the injection of supercritical CO2 (100bar/10MPa & 300K/27oC) fluid. This pressure is far lower than would be required for fracking as this would be detrimental to the purpose of developing the full potential of the storage reservoir. It is also far less than the cooling required for LNG at -162oC and reduction to 1/600th of its volume.
During and after a well is drilled the hole can then be tested by logging while drilling pre/post-hole using drilling, mud (weight, temperature, rock chip cuttings, fluids and gases) and geophysical tools, for example, Schlumberger uses combinations to determine critical petrophysical parameters, e.g., gamma ray (water for density), electrical resistivity (high for salinity/low for HC*[14]), nuclear magnetic resonance (porosity & permeability), pressure, rock and fluid properties etc. Also, open holes can be tested before/after installation of case tube enabling potential targets to flow under own pressure with the proviso that the usual safety equipment is operational and proper maintenance conducted, e.g., blow-out-preventor (BOP), unlike the BP Deep Water Horizon well in the Gulf of Mexico.
Fortunately, Australia has the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) managing Commonwealth waters under comprehensive legislation, with equivalent State and Territory (S&T) legislation with bilateral agreements for territorial waters. In Queensland the Greenhouse Gas Storage Act 2009 regulates onshore CCS sites (underground geological formations) under an Injection and Storage Lease (ISL) with Technical Specification requirements of their estimated storage capacity (ESC), composition and injection-rate volume (CIRV), monitor-report-verify (MRV) (also feeds into the National Greenhouse and Energy Reporting Act 2007) requirements, loss and migration pathways (LMP), and risks etc. This provides international partners with the confidence in Australia’s ability for CCS to meet accredited standards, e.g., ISO 27914: 2017, and gain carbon credits, e.g., Australian Carbon (CO2) Credit Units (ACCU).
Steam methane reforming (SMR) has been around for a century, whereby as the name suggests, methane is reacted with steam in the presence of a catalyst (Ni) to form hydrogen (H2). The H2 has been used to produce ammonia (NH3) for over a century as a feedstock for chemical manufacturing, e.g., fertilisers that made the green revolution in the 1950s possible.
Post carbon capture (PCC) of CO2 emissions has been around since the use of the first submarine Ictineo I (fish-ship) built by Narcis Monturiol 160 years ago that scrubbed (removed) CO2 from exhaled air. In modern times the main process of PCC uses mono-ethanolamine (MEA) solvent to capture CO2 and on heating releases it for storage, the solvent is then recycled. Even fuel oil generated emissions (NOx by 2010 & SOx by 2020) from large ships were required to be scrubbed under MARPOL Annex VI. The IMO regulated shipping industry was required to remove emissions and they complied, the same is likely for CO2 regulated emissions when sufficient signatories to international agreements is enacted regardless of whether some countries decide to not sign up.
None of the technologies are new, they are proven, they have and continue to be refined, and where there is a will (commitment) there is a way (Go-CQW 2CRUST) but this is only one way!
[1] 1.5oC requires 50% reduction by 2050
[2] IEA: International Energy Agency
[3] CO2: carbon dioxide
[4] Australian & New Zealand Standards
[5] Australian Petroleum Production & Exploration Association
[6] NH3: ammonia
[7] COP: Conference of the Parties, NDC: Nationally Determined Commitments
[8] CO2e: carbon dioxide equivalent global warming potential (GWP)
[9] Nm: 1 nautical mile = 1.85km.
[10] IMO: https://www.imo.org/en/OurWork/Environment/Pages/CCS-Default.aspx
[11] CH4: methane
[12] CSIRO: Commonwealth Scientific and Industrial Research Organisation
[13] NATA: Nationally Association of Testing Authorities or US DoE National Energy Tech (NET) Lab for CCS.
[14] HC: hydrocarbons