THE FUTURE 251
had little or no past exploratory effort. For areas that have been
extensively explored and are in a mature development stage, many
of the unknowns have been eliminated and future resources can be
evaluated with much more confidence. Even in some mature producing areas, however, uncertainty remains about the potential oil
and gas supply at greater drilling depths. Uncertainty also pervades
projections of whether potential reservoirs have been unrecognized
or bypassed in past drilling. Similarly, where resource estimates are
based on analogue comparisons between maturely explored areas
and unexplored areas, uncertainty is introduced because each area
or basin has unique characteristics.
Although our fundamental knowledge of the origin, migration,
and entrapment of oil and gas has advanced markedly during the past
30 years, the fact that incremental scientific advances are still being
made leads to additional uncertainty in resource estimation, especially in frontier areas or at great drilling depths. In other words, new
knowledge may lead to increases or decreases in estimates of undiscovered resources, but generally leads to a reduction of uncertainty.
Discovery is only the first step in crude oil and natural gas resource
development. The present state of technical knowledge in reservoir
geology and petroleum engineering, as well as existing regulations,
determine the spacing, completion, and production methods of
development wells (i.e. petroleum producing wells drilled after the
discovery well). As engineering and geologic knowledge increase,
our ability to withdraw larger increments of oil and gas from existing fields is enhanced. Thus, the sizes of fields in terms of ultimately
producible barrels of oil or cubic feet of gas increase with time.
Uncertainty as to ultimate sizes of discovered fields leads to uncertainty in estimates of size distributions of undiscovered fields in
areas with analogous reservoir characteristics and geologic histories.
Scientists can estimate the quantity of technically recoverable
undiscovered oil and gas based on the present state of geological
and engineering knowledge, modified by a consideration of future
technological advancement. However, the percentage of that quantity that may actually be discovered and produced is an economic
question. Uncertainties about future well-head crude oil and natural gas prices and costs of exploration and development adversely
affect all resource estimates. In short, uncertainties embodied in
economic assumptions lead to significant uncertainties in estimates
of economically recoverable resources and account for some of the
large differences among estimators.
had little or no past exploratory effort. For areas that have been
extensively explored and are in a mature development stage, many
of the unknowns have been eliminated and future resources can be
evaluated with much more confidence. Even in some mature producing areas, however, uncertainty remains about the potential oil
and gas supply at greater drilling depths. Uncertainty also pervades
projections of whether potential reservoirs have been unrecognized
or bypassed in past drilling. Similarly, where resource estimates are
based on analogue comparisons between maturely explored areas
and unexplored areas, uncertainty is introduced because each area
or basin has unique characteristics.
Although our fundamental knowledge of the origin, migration,
and entrapment of oil and gas has advanced markedly during the past
30 years, the fact that incremental scientific advances are still being
made leads to additional uncertainty in resource estimation, especially in frontier areas or at great drilling depths. In other words, new
knowledge may lead to increases or decreases in estimates of undiscovered resources, but generally leads to a reduction of uncertainty.
Discovery is only the first step in crude oil and natural gas resource
development. The present state of technical knowledge in reservoir
geology and petroleum engineering, as well as existing regulations,
determine the spacing, completion, and production methods of
development wells (i.e. petroleum producing wells drilled after the
discovery well). As engineering and geologic knowledge increase,
our ability to withdraw larger increments of oil and gas from existing fields is enhanced. Thus, the sizes of fields in terms of ultimately
producible barrels of oil or cubic feet of gas increase with time.
Uncertainty as to ultimate sizes of discovered fields leads to uncertainty in estimates of size distributions of undiscovered fields in
areas with analogous reservoir characteristics and geologic histories.
Scientists can estimate the quantity of technically recoverable
undiscovered oil and gas based on the present state of geological
and engineering knowledge, modified by a consideration of future
technological advancement. However, the percentage of that quantity that may actually be discovered and produced is an economic
question. Uncertainties about future well-head crude oil and natural gas prices and costs of exploration and development adversely
affect all resource estimates. In short, uncertainties embodied in
economic assumptions lead to significant uncertainties in estimates
of economically recoverable resources and account for some of the
large differences among estimators.