HOMEWOOD, PETER W., Elf Exploration Production, Pau, France

Abstract: Stratigraphy--Making Science of an Art 

Stratigraphy, the study of sedimentary strata, is a major source of both hard and soft knowledge in the exploration for and production of hydrocarbons. Over two centuries, the push and pull between science and technology has provided the backdrop to developments in specialist sub-disciplines linking industry and academia. Today the movement is toward integration of the varied approaches and data types that have been perfected.

The recent development of 3-D referencing and imaging technologies leads to the novel requirement for a much greater degree of continuity and precision in stratigraphic knowledge. For example, both standard facies models and classical biozonations lack requisite detail at the scale involved. They are no longer sufficient to constrain geological models for hydrocarbon prospect evaluation. They are even less satisfactory when developing reservoir models and when positioning production wells and their complex trajectories. Standard remedies enhance their performance by the use of quantitative data.

Theoretical advances are pulling the subjective practice of stratigraphy into the realm of hard science and technology. An example lies in the inversion of stratigraphic data, which may provide insight into the possible ranges in value of parameters such as subsidence, sea level variation, and sediment supply. High-resolution stratigraphic models, supplying more appropriate soft knowledge than facies models, are another example.

Tools such as 3-D imaging and inversion require a new look at the stratigraphic record, at what may be registered within it, and at how to exploit that information. The evaluation of multiple hypotheses, the measure of uncertainty, and the notion of error are gaining ground in the realm of stratigraphy. Rather than turning this art into a sterile science, these developments broaden the scope of stratigraphy to constrain geological interpretations within the boundaries that exist in the real world. 

AAPG Search and Discovery Article #90922©1998-1999 AAPG International Distinguished Lectures