RIASSUNTO
Abstract
Reductions in the environmental impact of exploration seismic can he achieved through improved planning from the scouting stage to post abandonment, environmental screening, EIA's geared to direct implementation of prevention and control measures, specifications in contracts and verification in the field through impact measurement and recording by supervisors.
Introduction
Exploration seismic is at the frontier of E and P business, and intensification in competition for new acreage has extended exploration into the remotest parts of the world including the more sensitive regions. Each new concession area contains a new set of environmental resources with differing sensitivity and value, which, if exploration is to he achieved at minimum cost to the environment, must be matched with appropriate environmental planning and safeguards.
For many years land seismic was viewed as a temporary operation spread over large areas, which produced negligible environmental impact. This view was maintained without much retrospective examination of the true impact of such operations . Environmental resources in exploration were once regarded as free, and the accrual of environmental costs went unmeasured. Misconceptions about the timescale and recoverability of the environment have also led to a false sense of environmental assurance. For example, mature rainforests may take 500 years to re-establish their original rich diversity (Ref. 1). Although revegetation of cleared areas with relatively few ""coloniser species"" can be established in a few years (assuming ideal conditions), this does not constitute replacement of the original rich vegetation. Should the soil be lost through erosion before revegetation, the forest may never recover, leaving a permanent environmental `debt'.
In 1989, a critical assessment of seismic operations and their impact in the field revealed the need for a revised approach to seismic in environmentally sensitive areas, to exploit the versatility in survey technology thereby avoiding impact.
Preventing the impairment of future environmental resources Preventing the impairment of future environmental resources (whether labelled as `environmental guardianship' or ""sustainable development"" has become a common denominator for responsible E and P industry. Environmental resources are to be treated as a valued asset, which provide environmental services and functions (e.g. water balance, erosion control) which must he maintained. In response to the moving target of environmental acceptability, industry must take the initiative to assess and minimise impact.
Environmental planning for seismic operations
How can minimum impact seismic be achieved?
An approach to the management of environmental resources from the conceptual stage to post abandonment of seismic operations in a comprehensive an systematic manner is summarised in Fig. 1.
* Policy and principles
Environmental protection starts with an operators policy and principles ( to which the management is committed), since principles ( to which the management is committed), since this sets out the primary framework upon which the business is based.
* Environmental sensitivity / risk screening
In areas of particular sensitivity, or where very little environmental information is available, it is valuable to conduct environmental screening at the scouting stage, with the specific objective of identifying environmental issues and requirements which could have a bearing upon future exploration operation, especially if additional time or resources would be required. Furthermore, it is often at the scouting stage that the type of seismic acquisition techniques, the associated logistics, and season of operation are decided. Since these decisions will undoubtedly affect the scale, degree and type of potential impact, the consequences of alternative survey approaches should he clearly understood.
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