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39. Petroleum and natural gas - Exploration, production, handling, storage
2. Environmental impacts and protective measures
2.1 Exploration
2.1.1 Nature and ecology
2.1.2 Sociology
2.1.3 Human health and occupational safety
2.2 Production
2.2.1 Nature and ecology
2.2.2 Sociology and economics
2.2.3 Human health and occupational safety
2.3 Handling and storage
2.3.1 Nature
2.3.2 Human health and occupational safety
3. Notes on the analysis and evaluation of environmental impacts
4. Interaction with other sectors
5. Summary assessment of environmental relevance
In the year 2000, petroleum and natural gas together will cover between 50 % and 70 % of the global energy requirement, and the energy-coverage ratio between the two will be about 2 : 1 to 1.5 in favor of petroleum. Obviously, in view of the corresponding scale of petroleum and natural-gas production, countries with major resources and corresponding development projects in the mining sector will have continued exposure to consequential environmental impacts. Due to the immobility of deposits and to the technical processes required to obtain the crude product, petroleum and natural-gas mining activities have their own specific environmental consequences. According to prevailing international definitions, a typical petroleum/natural-gas development project comprises the following three phases:
– exploration, on- and offshore, mainly by geophysical methods and exploration drilling, including a test phase following any discovery;
– production, beginning with field development drilling as a precondition for actual production, in the course of which certain phases are run through, up to and including basic conditioning of the raw material. The production of crude oil and natural gas requires a certain infrastructure;
– handling and storage directly following the production stage, i.e., prior to the further processing of crude oil and natural gas into energy-market products. These activities utilize part of the overall infrastructure.
2. Environmental impacts and protective measures
2.1 Exploration
Exploration is the term used to define the scientific prospecting and reconnaissance of raw material deposits by means of
– mapping/charting
– geophysics
– exploratory drilling.
Exploration for petroleum and natural-gas is based on a large-scale, onshore-specific aerial mosaic (photomap). In many regions of the world, superficial analysis of such maps can suffice to detect promising areas. Exploration then continues according to geophysical and geochemical methods of prospection. Finally, the superficial geological, geophysical and geochemical reconnaissance of promising structures requires confirmation by way of exploratory drilling, incl. well shooting, and the interpretation of drill cuttings and cores.
The environmental consequences of exploration are relatively minor on the whole, though the attendant drilling has a substantially higher disruptive hazard potential; cf. environmental brief Reconnaissance, Prospection and Exploration of Geological Resources.
2.1.1 Nature and ecology
Modern airborne mapping techniques employed at the beginning of the exploration phase pose no direct threat to the environment.
Depending on the applied techniques, the environmental consequences of geophysical prospection can extend over a period of months or years. Distinction must be drawn between gravimetric techniques and predominantly airborne magnetic measuring methods on the one hand, and seismic measuring methods on the other. The latter put geophysicists in a position to locate geological bedding boundaries at depths of several thousand meters by registering reflected compression waves. Indeed, the seismic reflection method is the most important prospecting tool, but it is not without consequences for the environment.
Even assuming a relatively brief disturbance, negative environmental impacts must be limited. Geophysical surveying teams, for example, live more or less self-sufficiently in remote areas for various lengths of time. Their access and transportation routes should preferably be by air or water, depending on the circumstances. Overland routes must include any deviations/detours necessary to avoid ecological disruption. With regard to blasting, the magnitude of the explosions used to generate pressure surges must reflect the state of the art. In some cases, vibroseismics may constitute a less disruptive alternative. Advanced receivers and amplifiers yield extensive information at lower pulse levels. Offshore blasting has destructive effects on marine life, particularly in the littoral zone. Alternative use of the air-pulse technique effectively protects marine flora and fauna.
On a regional basis, the most pronounced environmental consequences for nature and the ecology derive from deep drilling. If, however, state-of-the-art drilling equipment is (properly) used, the environmental impact frequently will remain far below what laypeople would expect. The main objective for drilling operations is to carefully plan, equip and conduct terminal exploration projects such as to either avoid negative environmental impacts altogether or at least reduce them to a tolerable level.
In connection with the preparation of drilling sites and the construction of access roads, due consideration must be given to subsequent renaturation, and disruption of the surface must be limited to the necessary minimum. The topsoil must be protected as well as possible (in covered heaps, etc.).
Drilling must be conducted such as to preserve the intactness of the rock strata and water-bearing horizons in their original, virgin separations through appropriate casing and cementation programs.
The media required for drilling, in particular the drilling fluid, should be chosen with attention to low environmental impact and subsequently recycled to the greatest possible extent.
Borehole safety, which is understood mainly as uninterrupted control over the dynamic pressure situation and borehole stability, must be ensured by adequately sized casings and cementation in combination with a blow-out preventor serving as a drilling-phase closure system (state of the art). Preventive measures in the form of technical equipment and disaster plans must be taken to limit the consequences of blow-outs. Such precautionary measures can prevent major environmental damage, which, while seldom irreversible, can be very expensive to repair.
Unavoidable, unrecyclable mining refuse like borehole cuttings and spent drilling fluid must be properly disposed of. With due regard for the environmental circumstances, preference must be given to dilution, thermally optimized incineration and/or encapsulation.
The slim-hole drilling technique must be considered as an alternative to conventional deep-well drilling. The technique is characterized by a much-reduced diameter, minimal use of operating media, less technical inputs overall, and such substantial time savings that the cost of drilling can be cut in half. Slim hole drilling does, however, presuppose certain geological conditions and is inherently unfeasible for deep wells.
The exploration drilling phase is not complete until all appropriate protective measures have been taken to counter the adverse environmental consequences of activities pursued in connection with successful exploration, i.e., the discovery of an exploitable field, which may last several years.
Any well that remains dry must subsequently be properly plugged, and the attendant aboveground facilities, including access routes, must be either recultivated or surrendered to some other controlled form of utilization.
2.1.2 Sociology
Exploration projects can seriously alter the social fabric of a country or region. Practically overnight, they expose native social systems to the activities and influence of multinational companies employing modern technical know-how. Conflicts of interest resulting from the immobility of prospective petroleum and natural gas deposits must be dealt with appropriately. The project must be integrated into the prevailing social structure as quickly as possible. That, in turn, requires the involvement of all social groups.
2.1.3 Human health and occupational safety
In general, urgent priority must be attached to occupational safety and to preservation of the health of petroleum and natural-gas exploration workers. The effects of such projects on parties not directly involved in the exploration work are insignificant.
The most obvious problems are those deriving from the difficult, privative work of geophysical surveying crews, especially in remote regions, and which continue through the end of exploratory drilling.
Since local personnel can be hired and trained relatively quickly for some of the work, appropriate individual support must be planned in. Medical care, hygiene and occupational safety must be guaranteed, and acceptance of worker protection measures, which demand a certain amount of training, must be ensured.
2.2 Production
Successful exploration is followed by the petroleum and/or natural-gas production phase, which includes:
– field development drilling, incl. complete preparations for production,
– aboveground installations and processing facilities,
– infrastructural measures.
A substantial share of the petroleum and natural gas resources that took millions of years to develop has been used up within a relatively short span of time. In the interest of long-term utilization, the human race must exercise a sense of responsibility in dealing with those natural resources - which are only renewable in terms of geological time spans. In reality, however, traditional oil-producing countries tend to adopt volume-oriented production strategies, accepting substantial environmental consequences as attendant phenomena. Production strategies in general are heavily influenced by the demand situation and as yet inadequate alternatives.
The time between exploration and production should be used to carefully analyze the project's anticipated environmental impacts for the duration of an average production field life (15 to 25 years for an oilfield and 50 to 100 years for gas) - and beyond. The analysis must be based on timely local and individual registration of the sociological, cultural economic, climatic and ecological situation, which, of course, differs widely around the world. The results of analysis must then be incorporated into each and every relevant resource production project.
The beginning of the field development drilling work should coincide with the establishment of requisite infrastructure, e.g., access routes, incoming and local service lines, and even the aboveground pumping facilities, processing plant, etc. With regard to the attendant environmental consequences, the reader is referred to the corresponding brief Road Building.
2.2.1 Nature and ecology
The long-term production phase of a typical petroleum/natural-gas project begins with the first regular output. Field development drilling prepares a deposit for production on the basis of the production geological and field engineering targets defined to reflect the underground conditions prevailing in the reservoir. The environmental consequences of exploration, as described in section 2.1.1 apply in full.
Especially in sensitive areas with valuable biotopes, the equipment used must be chosen with a view to minimizing space requirements. Thanks to advanced drilling technology (directional drilling with deflecting tools), a single onshore or offshore location now often suffices for tapping several square kilometers of a reservoir. And horizontal drilling can help to drastically reduce the overall number of boreholes.
Large-scale destruction or alteration of an area's flora and fauna (e.g., in a rain forest, tundra or coral reef) need not occur in connection with petroleum/natural-gas projects, which have relatively modest aboveground space requirements for technical equipment and infrastructure.
Through state-of-the-art plant dimensions in combination with necessarily redundant automatic monitoring equipment, emissions occurring under normal and disturbed operating conditions can be held at low levels.
Damage to the environment as a result of accidents, oil spills in particular, must be limited by safety-relevant controls, e.g., valving. Oil-contaminated water and soil must be rehabilitated by chemicobacterial means of artificially accelerating the biodegradability of hydrocarbons. A properly managed oil well causes no problems with regard to groundwater protection.
The economically efficient exploitation of natural energy vehicles must attach priority to controlling the environmental impacts while conserving the resource itself. For petroleum and natural gas, the conservation of resources covers both the effective utilization of their entire energy potential (by avoiding such activities as the pollutive flaring off of surplus production that cannot be directly utilized) and the alternative employment of high-tech production techniques.
2.2.2 Sociology and economics
The productive phase of an oil or gas field lasts on average about as long as a normal person's working life - if not even longer, as is frequently the case in gas production. That fact alone imposes a major social responsibility on the project. In continuation of the initial exploratory-phase measures, the living conditions, nutrition, education, health and cultural environment, including religion, of the personnel must be treated as importantly as the purely technical production facilities. Ghettoization must be countered, and the growth of social fabric must be promoted. Industrialization must be conducted cautiously and in a manner to allow incorporation of the cultural heritage of the aboriginal society.
2.2.3 Human health and occupational safety
One of the project executing organization's most important tasks is to promote health care, not only among the workers themselves, but also throughout the entire project region.
The same applies to occupational safety, which can and should be implemented in imitation of measures applied in industrialized countries. The assignment of well-trained and qualified personnel to such tasks is a crucial prerequisite.
2.3 Handling and storage
Handling and storage is understood here as the last step following exploration and production. The rough-processed crude products are transported by pipeline, railroad car or road tanker, and by inland waterways and oceangoing vessels, all of which requires special infrastructure. The products are stored in aboveground tank farms and underground stores, cavities and pore spaces.
The transportation/shipping, distribution mechanisms and finished-product storage scopes are not covered by this brief; please refer to the briefs relevant to adjacent sectors, e.g., shipping, ports and harbours, inland ports.
2.3.1 Nature
The requirements stated in section 2.3.1 apply analogously to transportation.
The large-scale storage of crude oil and/or natural gas requires special environmental safety measures, particularly with regard to the prevention of fires and explosions. Special importance is attached to leakage detection, alarm sounding and catchment techniques. Underground tanks are preferable to aboveground tanks, though they do call for more sophisticated safety engineering.
As an alternative to tank farms, underground storage in depleted mines, rock caverns, salt caverns and pore spaces has the least extensive environmental consequences. Pore spaces are only suitable for storing gas, and salt caverns demand appropriate utilization or disposal options (proximity to the ocean) for the brine. Both alternatives - pore spaces and salt caverns - presuppose the appropriate geological formations.
2.3.2 Human health and occupational safety
The large-scale handling and storage of oil and gas poses hazards such as the escape of hydrocarbons and the possibility of accidental explosions. Technical transportation monitoring measures and redundant storage safety engineering substantially reduce the risks involved. Pipeline safety can be ensured via monitoring stations, self-acting pressure control devices and aerial line inspections. Storage tanks and piping must be protected against corrosion.
3. Notes on the analysis and evaluation of environmental impacts
The environmental impacts must be evaluated with due consideration of the individual, project-specific situation. Project planning should be conducted with emphasis on the potential sociological consequences and the earliest possible involvement of local nationals. Environmentally relevant experience drawn from comparable projects must be duly considered.
The training of local manpower for all levels constitutes an important step in the direction of responsible management with a capacity for controlling environmental consequences. The project must be implemented in line with the pertinent laws, standards, codes, limit values and technical know-how of industrialized countries.
4. Interaction with other sectors
As the profitability of exporting natural gas is limited by the long transportation distances involved, many countries neglect its production. In that connection, the technical utilization of liquid natural gas (LNG) would appear worthy of promotion, since the transport problems would be relativized by the use of accordingly large tankers. By reason of its high efficiency, natural gas makes a good, nonpolluting substitute for other primary energy carriers.
The petroleum/natural-gas sector has numerous points of contact with other sectors, among the more important of which are:
- regional planning
- overall energy planning
- water supply
- planning of locations for trade and industry
- mechanical engineering, workshops, shipyards
- oil and fats.
References to adjacent sectors have been included in the appropriate passages of the above text.
5. Summary assessment of environmental relevance
Global experience shows that the petroleum and natural gas industry can maintain an ecological orientation with the aid of modern science and technology. Environmental awareness must be promoted by applying the standards of the most advanced industrialized countries.
Risks and undesirable environmental consequences must be minimized by responsibly implementing each project in accordance with its own ecological and sociological significance. Interdisciplinary management with the direct involvement of all sections of the population is appropriate and advisable.
Ecologically oriented operations presume the existence and adequacy of the requisite control organs. In that connection, an environmental protection officer carrying the responsibility for training the workers and instilling them with environmental awareness can be a major asset.
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