Integrated Sedimentary Basin Analysis for Petroleum Exploration and Production

ABSTRACT Integrated sedimentary basin analysis, as discussed here, is a twofold process. The first phase involves the construction of an integrated geologic model documenting how the basin formed, filled with sediment, compacted and matured within the natural system of the earth's geochemical-geological cycle. The second phase consists of utilizing the model to predict if an effective oil system has developed within the basin and delineating the prospects. INTRODUCTION The earth's geochemical-geological cycle can be regarded as a closed interacting system. Sedimentary basins are part of the earth' stectono-stratigraphic cycle of sedimentary basin formation, basin filling, compaction-maturation and inversion and eventual destruction. Integrated sedimentary basin analysis is a two fold process. The first phase involves the construction of a three-dimensional, genetic, geologic model, using maps, cross sections, and reports, which depicts the evolution of a basin. Sedimentary basins are large and complex natural systems which are the results of complex interactions of the earth's crust with the atmosphere, hydrosphere, and biosphere through the fourth dimension of time. In order to model such an integrated system the methods used to construct a genetic, three-dimensional, geologic model of a basin must also be totally integrated. The second phase of basin analysis consists of extracting the predicted subsurface conditions of source, maturation, reservoir, migration, trap and seal from the geologic model and outlining the potential for the occurrence of an effective petroleum system within the basin. Play and prospect delineation completes the basin analysis. A third step not discussed here is the economic assessment of the prospects. Rapid advancements in many realms of the geologic sciences have given exploration?s new conceptual and laboratory tools to model the earth. In order to take advantage of these scientific advances a modern, organized, goal-oriented, and integrated approach to project management must be adopted. THE EARTH'S GEOCHEMICAL-GEOLOGICAL CYCLE When trying to understand and model the operation of any large, interactive, complex natural system such as a sedimentary basin, it is important to back off from the details and look at the overal1 tectonostratigraphic system that produces sedimentary basins (Siever, 1974). Sedimentary basins are the result of the interactions of the earth's crust with the atmosphere, the hydrosphere, and the biosphere through time and as such they are part of the earth's geochemical-geological cycle (Figure 1). The analysis of the earth's cycle starts with an assumption of a general balance between inputs and outputs. On1y hydrogen and he1ium gases are 1ight enough to escape the closed system and be lost into space. Heat is lost by radiation and the albedo effects. However, the system can be regarded as being essentially in a steady state at least over long periods of geologic time (Figure 1).