Seismic Identities: Stratigraphic And Hydrocarbon Determination
Authors: Carey Bill 
Published: October 2008

The following is a brief investigation into additional understanding of hydrocarbon indicators and processing methods leading to stratigraphic investigations from seismic. The resultant hydrocarbon indicator net pay thickness graph combined with wave forms identification allows for a rapid approximation to sand thickness. Also, there exists the flexibility to adjust the determinations based on availability of additional geologic or geophysical control.

The results of pulse compression filtering in combination with spike-like deconvolution on present seismic data has the potential for stratigraphic interpretation from seismic data. The approach can provide sand-shale ratios of greater precision and reliability. The method is applicable to all marine provinces and is a possible approach to the stratigraphic understanding of land seismic data.

INTRODUCTION

The original concept for the investigation in seismic identities evolved from a study that attempts to resolve a rapid but simple method of thickness estimates of observed hydrocarbon indicators. Hence, the initial investigations were directed toward what constitutes a hydrocarbon indicator; how a hydrocarbon indicator is recognized and what would be entailed in a simple but creditable thickness measurement method. This method of thickness measurement was not to compete with precise modeling, but to be an exploratory tool to determine the merits of additional modeling requirements. In the process of attempting to devise a rapid and somewhat creditable measurement method, considerable reprocessing of offshore data was performed in order to gain increased resolvement of hydrocarbon indicator Characteristics. In the analysis of the reprocessed information several factors concerning the known stratigraphic environment of the area were enhanced. Thus, as additional efforts were performed, it became apparent that the onset to stratigraphic seismic data enhancement could become a practical exploration tool.

Hence, the evolvement of this report, "Seismic Identities: Stratigraphic and Hydrocarbon Determination." The paper will discuss briefly both hydrocarbon determination with some results and examples of those results in stratigraphic enhancement.

HYDROCARBON Determinations

The following discussion will investigate several aspects in the understanding and determinations of hydrocarbon indicators, their use and problems. A method of computing net pay thickness can be accomplished faster and to a higher degree of reliability, yet allowing the flexibility of change based on increased knowledge of the area. The use of amplitude is shown to be limited in section depth, thus stressing the importance of other characteristics in the determination of possible hydrocarbon indicators.

Tables 1 and 2 compare the positive and negative aspects of hydrocarbon indicator characteristics.

AMPLITUDE

The most controversial and referred to characteristic of a hydrocarbon indicator is amplitude. Amplitude is generally a prime factor in the initial determinations of a true hydrocarbon .indicator, and considerable effort in quality control has recently been devoted to amplitude preservation in seismic data processing methods. Thus, a discussion on the factors affecting amplitude has merit in the understanding of a usable and qualitative hydrocarbon indicator. The prime factors affecting amplitude are reflection coefficients (density velocity relationship) and boundary curvature (structural orientation - focusing variation).