Advances in Hydrocarbon Seep Sampling Strategies Using Real-Time Offshore Geochemical Analyses

Abstract

After years of constrained budgets and deferred plans for deepwater exploration and development, the deepwater industry is now more cautious and more efficient. Today’s deepwater exploration is focused on high‐grading a tighter exploration program to extract as much value as possible from a lean budget, and innovations that can improve efficiency are seeing growth in an otherwise difficult market. This growth has largely been driven by improved technologies and methodologies to explore and identify of seafloor hydrocarbon seepage. This is often colloquially referred to as “seep‐hunting” and has predominantly been driven by advances in both geophysical data acquisition and interpretation (via multibeam echosounder and subbottom profiler systems) and the pioneering use of shipboard geochemical screening analyses. Geochemical analytical methods such as gas chromatography of volatile hydrocarbons (C1‐C5) and extracted heavier hydrocarbons as well as total scanning fluorescence (TSF) of extracted aromatic compounds are employed at on the vessel to provide valuable screening for hydrocarbon seepage during campaigns at sea. Near real‐time shipboard analytical methodologies are well‐established in the academic world, however their implementation offshore in the hydrocarbon exploration industry has been hindered by perceived logistical and analytical limitations (e.g. Kvenvolden et al., 1979; Paull et al., 1996; Brooks et al., 1983; Barwise and Hay, 1996). Herein we demonstrate the commercial application of offshore geochemical analyses combined with geophysical and geological data, e.g. water column anomalies, backscatter responses, subbottom profiles, geomorphology, and seismic, for adaptive and optimized coring strategies. Data from seven regional‐scale commercial projects around the globe will be compared to show the efficacy of using these established geochemical practices from the academic world in an industry setting, and how the use of science‐driven methods is improving the data quality and reducing the risks in commercial hydrocarbon exploration. These offshore geochemical data exhibit a robust correlation with data produced by various shore‐based laboratories, which serves as inter‐laboratory validation for offshore methods. Integration of shipboard geochemical analyses with geophysical and geological data provides a robust, adaptive sampling strategy that optimizes collection of geochemically significant data into a single package.

AAPG Datapages/Search and Discovery Article #90349 © 2019 AAPG Hedberg Conference, The Evolution of Petroleum Systems Analysis: Changing of the Guard from Late Mature Experts to Peak Generating Staff, Houston, Texas, March 4-6, 2019