Petroleum Trap Associations: a Basis for Systematic Exploration: ABSTRACT

Abstract

A strategy that considers possible trap types in each volume of potentially petroliferous rocks becomes increasingly attractive as the remaining petroleum prospects become more elusive. This approach calls for cataloguing systematically the numerous lithologic configurations possessing trap-forming potential that may result from the basic processes of erosion, deposition, diagenesis, and deformation, as experienced by the particular strata. These varied lithologic configurations are then considered in terms of their areal and time-stratigraphic associations. A wide variety of oil and gas entrapments is commonly related to one or more large-scale trap-forming features, such as a paleodrainage system or a salt dome. Traps associated with such features commonly develop during intervals of exceptionally rapid change, certain of which may be regarded as distinct trap-forming events. Some changes, like river avulsion, may be caused by internal processes, whereas others, like particular (series of) changes in sea level, originate outside the local systems and so may affect extensive regions. The objective is to predict the potentially trap-forming lithologic configurations that might occur on each feature at the stratigra hic position of each event. However, the accumulation-forming potential of these configurations and events must also be considered. This is revealed most directly by studies of existing production, which may then be used to guide exploration for related accumulations and to predict new types and locations of entrapment. Since the trap-forming features and events are frequently related to the other prerequisites for petroleum accumulation, consideration of accumulations provides some integration of all the prerequisites. End_of_Article - Last_Page 638------------