Application Of Sequence Stratigraphy To Hydrocarbon Exploration
Authors: Wornardt W.W. 
Published: October 2008

In the quest for hydrocarbons, both the exploration and exploitation programs can be greatly enhanced by applying seismic sequence stratigraphic analysis. This technique provides the explorationist with the capability to recognize, discover and evaluate new hydrocarbon reservoirs and to reduce the risk in management's decision making. The play concepts, source, seal and traps associated with different reservoir sands and their associated 10wstand, transgressive and high stand systems tracts are an important aspect of this type of analysis

INTRODUCTION

Seismic Sequence Stratigraphy Analysis is the integration of high resolution biostratigraphic and pale bathymetric data, well-logsignatures and seismic-reflection profiles (Fig. 1)(available in full paper). This methodology permits the geologist and geophysicist to divide an outcrop, well and stratigraphic section and seismic section into a series of third-order depositionalsequences, chronostratigraphic maximum flooding surfaces and sequence boundaries. The maximum flooding surface condensed section, maximum flooding surface and sequence boundaries are age dated on the basis of high resolution biostratigraphy andstratigraphic analysis is to succeed. These are correlated with the global cycle chart (Fig 2)(available in full paper). Subsequently, these third order depositional sequences are subdivided into systems tracts on the basis of characteristicIithology,, Pale bathymetry, well-log signatures and seismic reflection patterns (Fig. 3)(available in full paper).

The most important contribution to seismic sequence stratigraphy in the past four years has been the addition and integration of high resolution biostratigraphy and pale bathymetry. The high resolution. biostratigraphy and pale bathymetry are anabsolute must if seismic sequence data sets are extremely important because they provide a means of recognizing maximum flooding surface condensed sections which in turnprovides an accurate means of identifying the maximum flooding surfaces on well-logs and seismic profiles which in turn provides ameans of age dating these surfaces and correlating them with the global cycle chart. The pale bathymetry provides a means of accurately identifying the water depth at which the reservoir sands were deposited which in turn provides a means to help select the various types of systems tracts that are associated with these shallow or deep water reservoir sands. For instance, the blocky well-log signature of both the deep waterlowstand systems tract basin floor fan complex and the very shallow water prograding or transgressive systems tractincised valley fill can easily be differentiated based on the pale bathymetry. The maximum flooding surface condensed sections are also important because they are usually associated with source rocks andprovide an excellent seal for hydrocarbons.

If explorationists do not integrate high resolution biostratigraphy andpale bathymetry into their exploration or exploitation program they are not performing seismic sequence stratigraphic analysis but they are merely performing what they have always performed, seismic stratigraphy. If explorationists state that they have performed seismic sequence stratigraphic analysis, even though they have not, and the resulting $10,000,000 dry hole was supposed to be based on seismic sequence stratigraphic analysis, and it was not, the result is: "seismic Sequence Stratigraphic Analysis does not work. "