Table of Contents
1.1 The nature of environmental mitigation
When we say environmental aspect, we mean an element of an organisation’s activities, products or services that can interact with the environment. When we say environmental impact, this is a planned or known or expected impact upon the environment. When we say environmental risk, this is an unplanned or unexpected event that gives rise to environmental harm, so something accidental. Environmental regulations frequently require offsetting mitigation for negative impacts of extractive activities.
A couple of practical concepts to carry out mitigation measures are BAP and BAT. Best Available Practice (or BAP) applies the most appropriate combination of environmental control measures and strategies. Best Available Techniques (or BAT) is about the best available techniques which are the latest stage of development — so state-of-the-art process or facilities or methods operation — which indicate the practical suitability of a pretty particular measure for limiting discharges, emissions, and waste.
Mitigation can occur on-site or off-site. On-site mitigation entails enhancing environmental attributes at the development site to compensate for ecological harm caused at that site. In many situations, on-site mitigation is not feasible, and the focus transfers to off-site mitigation, in which environmental attributes are improved elsewhere to compensate for ecological harm at the development site. Anticipation and mitigation by energy firms can also help address the issues that can accompany the urbanisation that often occurs around oil and gas developments.
O&G companies can help operationalise the Sustainable Development Goals (SDGs) in their core business practices by integrating them into their corporate systems, policies and processes. Different projects will have disparate impacts on different SDGs. Therefore, identifying the local area’s social, economic and environmental baselines and the potential implications of operations will inform engagement, contribution, and mitigation measures. Other baseline assessments considered in environmental mitigation include human rights, health, lifecycle assessments and landscape-scale plans .
1.2 The exploration and production lifecycle
When we refer to upstream, we talk about the exploration and production life cycle, consisting of five phases: survey, exploration, development, production, and decommissioning. Let’s illustrate the different environmental impacts at each stage with an offshore oil & gas example.
In the survey, which is the first phase, engineers try to understand the geology, so where in the seabed do we have a reservoir. To do that, they perform a seismic activity, which means we use vessels equipped with emitters that send waves down to the seabed and then collect back these waves. The data collected will be analysed to draw geological maps, which will later define where there might be geological traps for oil and gas — and eventually drill a well. Of course, this activity is associated with environmental impacts: we have atmospheric emissions from the seismic activity, limited discharges to the sea, the vessel could go into an accident, etc. Yet, the major impact of seismic activity is its impact on mammals because it generates noise and generates waves, which deters mammals.
The second phase would be exploration. There is already a geological map at this stage, and we do know where we might expect oil and gas. So, a rig or a module, a mobile offshore drilling unit, is placed above the well location and drilling is started. This activity is also associated with impacts: atmospheric emissions, which are basically from the rig itself because it has combustion, generators on board, and also from helicopters that are used to transport personnel from onshore into the rig as well as from support vessels which are moving continuously back and forth between the offshore and the onshore. If we move deeper or into more complicated geology, oil-based mud is required and consequently, drilling cuttings become hazardous materials.
If we do have a discovery, then we move into development and production. Here, oil and gas are taken up into the rig and then processed for use. This phase is also associated with multiple environmental impacts: from emissions to discharges, going through accidents and routine impacts. In the case of accidents, we are talking about fire or explosion, an oil spill, a blowout (uncontrolled release of crude oil or natural gas from a well), a vessel incident, a helicopter crash on the way on the route between the rig and the onshore, among others. We will go over decommissioning and closure issues later in this document.
Besides offshore O&G, there are also some specific issues relating to hydraulic fracturing. For example, modelling earthquake rate changes and the analysis of earthquake seismicity data by the USGS [2, 3] suggest that the significant increase in earth movements over the past few years is likely triggered by waste liquids, such as flowback from hydraulic fracturing operations and coproduced fluids, being injected under high pressure into deep geologic formations.
2 THE PHASES PRIOR TO ENVIRONMENTAL MITIGATION
2.1 Assessing impact significance
Several methods and processes support the prioritisation of environmental impacts and risks when establishing mitigation activities. The best recognised of these methods is to use matrices for whittling down the long lists of ecological impacts and threats to a shorter list of those requiring control. Figure 2 provides an interpretive matrix that enables consideration of the sensitivity receptors against the magnitude of change; it can be used before prioritising the bulk of attention to receptor interactions that fall within the bottom right to the matrix.
When assessing and prioritising environmental impacts and risks, the criteria used to do this should be clear, unambiguous, robust, and proportionate to the project. This is illustrated by the weighting that should be applied to consider the severity of consequences.
The potential impacts of each proposed activity and the alternatives can also be assessed using the impact significance classification system  as follows:
- Class I: Significant and Unavoidable Impact. Class I impacts are significant adverse environmental effects that cannot be mitigated to a ‘less than significant’ level by applying feasible mitigation measures.
- Class II: Less Than Significant Impact With Mitigation Incorporated. Class II impacts are significant adverse environmental effects that can be reduced to a level of ‘less than significant’ with feasible mitigation measures.
- Class III: Less Than Significant Impact. Class III impacts are adverse environmental effects that have been determined to be comparatively minor because they do not meet or exceed the subject-specific criteria established to gauge significance.
- Class IV: No Impact. Class IV impacts do not have any adverse or beneficial environmental effects.
- Class V: Beneficial Impact. Class V impacts result in favourable environmental effects.
2.2 Environmental appraisal
The environmental mitigation program for an asset must include detail and supporting information on the potential environmental impacts of the proposed remediation and mitigation activities themselves; this is based upon a starting presumption that, wherever possible, all resources will be reused, recycled, or disposed of through BAP.
The environmental appraisal must be documented in a report providing details of any mitigation measures or remedial works required to manage or address the significant environmental impacts or risks. The following steps outline the staging process that can be followed to live an environment appraisal for mitigation in oil and gas.
The environmental appraisal process can be broken down into four key steps. The first step is defining mitigation activities or parameters and understanding the nature and extent of proposed actions. The second is to identify potential mitigation activities and environmental receptor interactions. The third is to characterise the baseline environment. This is based on understanding the receiving environment and considering the relevant environmental aspects, impacts and risks that pose and are opposed by the mitigation program. Step four is to assess the significance of the environmental interactions, factors, effects, and risks; at this stage, you will also seek to define mitigation measures according to BAP and BAT. Once all this has been done, it is documented with an environmental assessment report.
Part of the environmental mitigation activities require operators to develop and manage a public consultation process — this should be proportionate to the level of interest from stakeholders. While stakeholder engagement and consultation is a topic on its own, it is worth highlight the complexity of stakeholder interactions associated with remediation, decommissioning, and closure programs; this is because a large number of stakeholders may have relevant environmental concerns, constraints, or information.
It is also worth noting that consulting and engaging with stakeholders provides an optional process and informed decision-making during environmental mitigation. During the planning process, operators will consult with government departments, agencies and non-government agencies; this may include, but is not restricted to, organisations with some environmental concerns or constraints upon the program — some organisations may even have information that could support the environmental appraisal. The stakeholder engagement process can take up to 12 months, so it is recommended that the stakeholder consultation and communication process is first well understood and considered, and then it commences at a very early stage.
3 SUMMARY OF RESOURCES AND MITIGATION MEASURES
A variety of resources and issues are described below with suggested mitigation measures .
3.1 Air resources
This includes exposure to noise, odours, volatile chemicals, silica dust from proppants, and construction dust. Methane and other GHG released as fugitive emissions from oil and gas wells and fracking operations are seen by some researchers as a concern . Besides fugitive emissions, numerous VOCs and semivolatile organic compounds (SVOCs) are present at drilling and production facilities related to operational chemicals such as fuels, lubricants, cleaners, drilling additives, or fracking chemical additives. Old or abandoned oil, gas, and water wells may not have proper construction and lack adequate cement seals. Consequently, these historic wells may act as conduits for methane emissions from the subsurface into the atmosphere. Flaring of unwanted natural gas contributes to GHG. On a global scale, the use of fossil fuels produces GHG.
Mitigation measures of air resource impacts focus on:
- Minimising surface disturbances and the size of cleared vegetation as a way to reduce construction‐related dust.
- Limiting vehicle speed to reduce airborne fugitive road dust and post and enforce speed limits.
- Revegetating disturbed areas with native plants and use erosion controls (wattles, berms, silt fences, fibre mats, etc.) to control stormwater runoff and wind erosion.
- Educating workers to minimise activities that contribute to generating fugitive dust emissions.
- Minimising slash burning of vegetation debris after construction clearing, and, instead, process wood and plant debris using wood chipping equipment to generate wood mulch that can be used for soil erosion control.
- Recycling and capturing currently flared methane use more fuel‐efficient engines, motors, and pumps to reduce fuel‐related emissions.
- Inspecting by performing field screening and well and pipeline repairs can reduce fugitive methane emissions from equipment.
- Optimising planning and minimising vehicle trips reduce traffic and emissions, as well as roadway degradation.
- Locating and adequately destroying all nearby old or abandoned wells is not a conduit for fugitive methane emissions.
- Reinjecting produced natural gas or using it in operations will reduce the energy the waste of flaring.
3.2 Ecological resources
Wildlife impacts, habitat fragmentation, and invasive, nonnative species are the issues included in ecological resources. The unconventional resource assessment and extraction require clearing substantial amounts of land and grading for drilling/production pads and pipelines and developing new or improving access roads. For remote production pads, new roads to nearby towns and supply centres will also be constructed. The additional traffic and air pollution from trucks, barges, and trains also disrupt wildlife in the area. These changes also can impact landscapes as well as the quality of life.
Mitigation measures of ecological resources impacts comprise:
- Minimising access road footprints to lower dust.
- Maintaining connected and continuous wildlife corridors allows for the migration of larger animals while minimising fencing and walls that would block animal movement.
- Designating off‐limit areas to protect wildlife and minimise activities and operations in sensitive feeding, nesting or breeding areas, and limit off‐road vehicle use.
- Locating drilling and production facilities outside of landslide zones, beyond the 100‐year floodplain, and not in areas where flash floods destroy equipment and damage the nearby ecological resources.
- Developing a plan to plant native vegetation and a maintenance plan to control invasive species and noxious weeds that could impact wildlife.
- Keeping vehicles and portable equipment clean of invasive seeds and only reseed with native species.
- Limit the number of stream crossings when locating access roads, and allow for the safe passage of fish and aquatic life.
- Educating workers, contractors, and site visitors to avoid harassment and disturbance of wildlife and instil the importance of ecological resources and protection methods.
- Scheduling site activities to avoid disturbance of ecological resources during critical times of the year, such as periods of courtship, breeding, nesting, lambing, or calving.
- The night is a critical period of the day for certain species. Therefore, minimising noise, when possible, and eliminate all unnecessary night lighting.
- Placing bird or animal netting on open reserve pits and trenches and using wildlife deterrents or other exclusionary devices to prevent access to them.
- Using only safe, nonpersistent, immobile, and biodegradable herbicides, rodenticides, insecticides, and pesticides, applying the compounds per the manufacturer’s directions.
3.3 Cultural and paleontological resources
Previously inaccessible historical artefacts, petroglyphs, and fossils may be collected or vandalised by persons using newly constructed access roads. Disturbance of the surface while building drilling/production pads and pipeline trenches can damage buried cultural and paleontological resources. Excess air pollutants from vehicles, pumps, engines, and vibrations caused by activities can damage fragile rock art and some historical artefacts.
To preserve the value of cultural and paleontological heritage and scientific evidence, here are some practical actions to implement within oil and gas developments:
- Minimising access roads and pads, map and preserve cultural and paleontological resources before drilling, installing security cameras at remote sites, vigorously prosecuting vandals, as well as fossil and artefact collectors who are vandalising or stealing on private or public lands.
- Performing a records search of known historic buildings and archaeological or paleontological sites in the area.
- Preparing a cultural or paleontological resources management plan if those resources are known to be present or are highly likely to be in the oil and gas development area.
- Performing periodic monitoring and inspection of significant cultural or paleontological resources in the area of the oil and gas development to reduce the potential for collecting and vandalism, and notify state or federal authorities if damage to cultural or paleontological resources has occurred.
- Educating workers and the public on the consequences of collecting or damaging artefacts and the potential for an unexpected discovery of a cultural or paleontological resource in the area.
- Unexpected discoveries would cause a work stoppage pending inspection by an appropriately trained professional.
3.4 Water quality
Spillage of hazardous compounds or leakage of produced liquids or gases produced by brines and other chemicals can impact surface or groundwater quality. Water quality of surface and shallow groundwater can be degraded by contamination by toxic compounds, including shallow aquifers with spilt liquid compounds from the surface. Leakage can occur in lined pits, from above or underground storage tanks and tanker trucks, oil tanker ships or barges, tank railcars, pipelines, etc.
Besides the possibility of leaking fluids from poorly contained or spilt sources on the surface, hydrocarbons, metals, NORM, brines, and drilling or fracking wastes could also enter surface waters or shallow water supplies should connections between the contaminant sources exist to allow entry.
Measures for mitigating impacts on water quality include:
- Release of hazardous chemicals can be addressed by operators with best management practices, including closed‐loop drilling systems, closed‐top tanks with secondary containment for all liquids, covered bins with secondary containment for all solids and sludges, and continuous inspection and monitoring.
- Training hands‐on field workers (operator workers, vendors, subcontractors, etc.) and on‐site supervisors and managers on the proper handling, use, storage, and disposal of all hazardous materials minimises the chance for spillage or leaks.
- Regular worker training and cleanup drills using spill response equipment prepare workers for an emergency.
- All operators should be transparent and offer full disclosure of all chemicals on‐site, which will allow for the testing of these compounds.
- Having a third‐party professional environmental scientist, geologist, or engineer collect and document site conditions and collect representative water, soil, or air samples before operations begin reduces potential conflicts and unnecessary controversy.
- The condition of nearby water supply wells should be documented using a video camera, logging, and water chemistry testing. After the fact, advanced isotope geochemistry using ratios of various elements can provide information to delineate different sources of contamination.
- As a precaution, regulatory agencies should require severe setbacks for oil and gas wells, pits, tanks from nearby water supply wells and surface waters and neighbours.
- Depending on subsurface conditions and materials used in well construction, too many rural wells are past their design lifespan of 50 years. Normal well deterioration is common and may include failed cement seals, well casing collapse or corrosion, naturally occurring microbial growth, iron precipitation, scaling, and pitting. These factors, which likely predated drilling operations, can, nonetheless, greatly impact the quality and quantity of local groundwater supplies.
3.5 Landscapes, scenic views, night skies
Not only are the obvious areas near drilling pads, production facilities, and pipelines affected, but some environments and communities that are located hundreds or even thousands of miles away from the nearest hydraulic fracturing operations are also potentially impacted. Areas with mines for fracking- and drilling‐related resources; mines for proppant sands or bentonite used in drilling muds; and resource processing plants, transportation hubs, refineries processing the crude oils, natural gas processing plants, bulk storage terminals and ports, and disposal facilities. Environmental concerns about oil and gas fields are amplified in pristine, highly visible sensitive areas such as wetland areas.
Flaring unusable methane from the Bakken oil production in North Dakota disrupts the serenity of the night skies (Figure 5). Due to various economic realities and demands on operators in many basins, including debt obligations, drilling and production requirements to maintain the lease, legal requirements, investor demands for production cash flow, and rapid crude oil production are the norms.
Natural gas reserves in the right location at the right time are a valuable commodity. The crude oil is produced and sold immediately to address the economic realities listed above. Since there are no pipelines to carry the methane to market, the coproduced methane is flared as a waste product, increasing GHG and lighting the night sky in a brightness seen from space. Scenic views and natural soundscapes are likewise impacted by drilling and production activities.
- There is a growing trend that conservation efforts could be considered holistically instead of employing a site-based approach. Therefore, Mitigation efforts could be more effective if they consider the impacts on and risks to habitats and biodiversity near a site and the broader landscape, including ecosystems, biodiversity, local communities, and economies.
- Implementing a strategy that can direct regional conservation priorities and manage cumulative effects. To do this, collaboration and information-sharing with other stakeholders are required.
- Using a computer simulation of the development and visualisation techniques to evaluate potential visual impacts early in the permitting process.
- Concealing facilities into the surrounding environment using trees and vegetation as a visual barrier.
- Using paints and netting on equipment to blend in with the character of the area. To reduce reflection and glare, use non-reflective coatings and paints. Avoid using reflective silver-coloured galvanised pipes and metallic coated surfaces on‐site.
- Burying wires and cables if possible.
- Using security lighting with motion detectors to limit nighttime lighting.
- Cessation of flaring is also a mitigation measure.
3.6 Seismicity Issues
Injection of large volumes of fluids during hydraulic fracturing operations occurs; however, the impacts are uncertain. The injection of waste fluids from oil and gas operations into large-diameter injection class II injection wells can cause low‐magnitude tremors. By 2014, Oklahoma had 528 magnitude 3.0 and greater earthquakes, 300 times the number of earthquakes recorded in 2008 .
This is an exploratory field in the oil and gas industry; however, seismicity issues impacts are generally managed by:
- More recycling of drilling and backflow water would reduce the need for disposal and associated waste injections.
- Monitoring microseismicity in fracking areas and, more importantly, waste fluid disposal areas provides information for continued evaluation, discussion, and mitigation if needed.
4 CASE-SPECIFIC MEASURES
4.1 Response to oil spills
Oil spill response is a process that has evolved to address lessons learned and ensure systemic coordination resulting in efficient cleanup operations . For example, in the U.S., the federal requirements to have adequate equipment, trained personnel, and oil spill response plans that are exercised regularly ensures everyone has a chance to practice their roles and responsibilities.
The grounding and release of oil from the Exxon Valdez in 1989, the Deepwater Horizon event in 2010 and other major events caused a major revamping in the pollution prevention for offshore drilling and major changes in the requirements to conduct spill exercises. In general, laws give the federal government enforcement authority over the responsible parties and have planning and preparedness components under the Oil Pollution Act of 1990.
The term responsible party refers to the owner or operator of a vessel or facility from which oil is discharged. The regulatory role that the accountable party performs during the oil spill is a major distinction between a Stafford Act response to a natural disaster and an oil spill exercise or event. The oil spill response community operates within a more extensive preparedness and response system made up of government public and private stakeholders. The responsible party or the federal government has the ultimate responsibility for containing mitigating and cleaning up the spill.
An oil spill response can be complicated and evolve. The requirements to have oil spill response plans and exercises are critical to ensuring that everyone knows and practices their roles and responsibilities. These exercises do not just happen, and careful thought goes into planning the training to incorporate recent lessons learned, conducting the exercise to practice skills, and evaluating the activity to enhance response capabilities continually.
4.2 Offshore decommissioning
Let’s start by providing a little bit of context around the policy and regulatory framework governing environmental appraisal for decommissioning offshore assets. Most nations are signatory to several international conventions that govern activities in the marine environment. Some of these place obligations which impact offshore oil and gas and, more specifically, upon the decommissioning of offshore assets.
To put this into a bit more context, it happens that states’ international obligations and policies on the decommissioning of offshore installations have common origins in the United Nations Convention on the Law of the Sea 1982. This includes a requirement that any installations and all abandoned or disused structures should be removed to ensure safety and navigation; it also consists of a need to remove out of the assets should have due regard to fishing and the protection of the marine environment.
In 1992 the Convention on the Protection of the Marine Environment in the Northeast Atlantic (the OSPAR Convention) was agreed. The most significant obligations for decommissioning offshore oil and gas operations a set out in OSPAR decision 98-3, which requires that the topside of all installations must be returned to shore and that all steel installations with jacket weight less than 10,000 tonnes (in air) must be removed entirely for reuse, recycling or final disposal on land. The decision recognises that it might be challenging to remove the footings of oversized steel jackets weighing more than 10,000 tons; similarly, it acknowledges difficulties with removing concrete installations.
Principles and stages
So, at this point, it is appropriate to ask how do these obligations translate into a requirement for environmental assessment. But, first, let’s discover some of the practicalities and approaches to undertaking environmental appraisal for offshore decommissioning.
The vast majority of policies and practices on decommissioning are underpinned by two fundamental principles: a precautionary principle that decommissioning should aim to achieve a clear seabed whilst acknowledging that this will not always be achievable, and a polluter pays principle . The latter sets out an expectation; organisations who have benefited from the exploitation or production of hybrid hydrocarbons in the continental shelf will bear responsibility for decommissioning and any cleanup of this required.
These set the scene to characterise and understand the environmental impacts and risks of an offshore decommissioning process and the associated decommissioning program. Practically, there are five key stages in the decommissioning process; these start before cessations of production and continue by early identification of options to detailed assessment and drafting of the decommissioning program submitted to base.
At stage two of this process, the decommissioning program is submitted to base for consultation; this goes to operate and other interested parties for consideration. Then, at stage three, there is a formal submission for the decommissioning program in the hope of approval. The chosen decommissioning options, set out and disposed of in the decommissioning plan program, must be supported by an environmental appraisal at both stages; this should assess the impact of the project on the environment and include information on the energy balance and emissions from the decommissioning options considered. The appraisal also needs to consider the environmental impact of any explosives likely deployed during decommissioning activity.
4.3 Petroleum lubricants
This section reviews effective environmental impact mitigation for petroleum-based lubricants to reduce their negative persistence during usage and end-of-life disposal. It is time to explore initiatives that may enhance the ecological effectiveness of lubricating oils from the composition design perspective. Reference is made to mineral base oil processing, blending, application and disposal of petroleum lubricants, and current best practices that minimise or eliminate adverse environmental impact throughout the product’s life cycle.
Unlike petroleum fuel which is burnt and emitted as gaseous by-products to the environment, for which exhaust-system catalytic converters have since been fitted to vehicles to release less harmful gases, lubricants are typically dumped as liquid waste. This poses severe environmental damage in the form of soil degradation, water contamination and interference with ecosystem balance. Lubricants, both used and fresh, can cause considerable damage to the environment mainly due to their high potential for severe water pollution. In addition, the additives contained in these products can be toxic to flora and fauna. In recycled fluids, the oxidation products can be highly toxic as well. Persistence in the medium largely depends upon the base fluid; however, if very toxic additives are used, they cause this negative persistence.
The feasibility of eco-friendly bio-lubricants for total loss applications is under development given thermal stability challenges and the use of nano solid lubricants to replace fluids and grease for severe space operations. Reduction of emissions resulting from sulfur in additives is one way to save the environment, among other efforts such as recycling of used oil and proper oil handling to minimise spills and leakages into the biosphere. The three pillars guiding engine lubricant technology advancement towards environmental impact mitigation are the need to achieve significant fuel economy, appreciably extend the oil drainage period and minimise gas emissions into the environment through sulfur-less additive packages.
Recently, there has been a resurgence of eco-friendly lubricants due to increased environmental efforts to reduce the use of petroleum-based lubricants. Still, mineral oil remains to be the largest constituent and the foundation of most lubricants. Compared to petroleum-based lubricants, bio-based lubricants have a higher lubricity, lower volatility, higher shear stability, higher viscosity index, higher load-carrying capacity, and superior detergency and dispersancy; therefore, they are excellent mitigation alternatives to petroleum-based oils.
Discharge into sewage, recycling, burning, and landfill and discharge into sewage and waterways are some of the disposal methods observed for used lubricant. There are strict regulations in most countries regarding disposal in landfills and discharge into the water as even a meagre amount of lubricant can contaminate a massive amount of water. Most regulations permit a threshold level of lubricant that could be present in waste streams. Companies spend hundreds of millions of dollars annually in treating their waste waters to get to acceptable levels.
It was established that regeneration brings about meaningful net relief concerning six environmental performance indicators, namely: resource depletion, greenhouse effect, acidification, nitrification, carcinogenic risk potential and fine particle emissions. Figure 6 illustrates the ratio between the average impact of regeneration concerning the indicators mentioned earlier and the equivalent burden that would result from primary production. It demonstrates that regeneration has a considerably lower environmental obligation than the processes it substitutes. It can be seen that the lower the impact, the better for the environment.
Concerning the other recovery options where waste oils are used as a heavy or light fuel, regeneration outperforms incineration from an ecological perspective about the six environmental performance indicators. Furthermore, with the evolution towards increasing synthetic base fluids in lubricants, the omitted ecological burden resulting from regeneration substituting primary production will increase in the future .
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