Spectral remote sensing for onshore seepage characterization: A critical overview

Abstract

In this article, we overview the application of spectral remote sensing data collected by multi-, and hyperspectral instruments in the visible-near infrared (VNIR), short-wave infrared (SWIR), and longwave infrared (LWIR) wavelengths for characterization of seepage systems as an exploration indicator of subsurface hydrocarbon (HC) accumulations. Two seepage systems namely macro-, and microseepage are recognized. A macroseepage is defined as visible indications of oil and gas on the surface and in the air detectable directly by a remote sensing approach. A microseepage is defined as invisible traces of light HCs in soils and sediments that are detectable by its secondary footprints in the strata, hence an indirect remote sensing target. Based on these broad categories, firstly, a comprehensive set of well-described and reliable remote sensing case studies available in the literature are thoroughly reviewed and then systematically assessed as regards the methodological shortcomings and scantiness in data gathering, processing, and interpretation. The work subsequently attempts to go through seminal papers published on microseepage concept and interrelated geochemical and geophysical techniques, exhumed HC reservoirs, lab-based spectroscopic analysis of petroleum and other related disciplines from a remote sensing standpoint. The aim is to enrich the discussion and highlight the still unexplored capabilities of this technique in accomplishing exploration objectives using the concept of seepage system. Aspects of seepage phenomenon in environmental pollution and uncertainties associated with their role in global warming are also underlined.This work benefits from illustrative products generated over two study areas located in the Ventura Basin, State of California, USA and the Tucano Basin, State of Bahia, Brazil known to host distinctive macro-, and microseepage systems, respectively. In conclusion, we recommend further research over a diverse range of seepage systems and advocate for a mature conceptual model for microseepage phenomenon. ), whereas microseeps, which are argued to occur in a near vertical fashion over an accumulation, are employed as a targeting tool for petroleum exploration.Recent investigations have also revealed that seeps are a potent source of methane (with ethane and propane) greenhouse gasses to the atmosphere. It has been estimated that in the natural methane budget, seeps are the second most important source of emissions after wetlands. The estimates also reveal that onshore seepages are a more significant emitter of CH 4 than their offshore counterparts (Etiope, 2015;Etiope and Ciccioli, 2009;Etiope and Klusman, 2010;Etiope et al., 2008).Over the years, a diverse range of techniques, including remote sensing, has been employed for seepage detection. The remote sensing approach holds a great promise for this aim because it is a fast and costeffective tool applicable to different operational scales for both direct and indirect seepage mapping. In the marine environment, this technology alre...

Toward Quantifying Oil Contamination in Vegetated Areas Using Very High Spatial and Spectral Resolution Imagery

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Petroleum exploration in Africa from space

“…Figure 4. Bouguer gravity map of the West and Central Africa Rift System (from [9]) with superimposed the licensing blocks of South Sudan case study, Lake Albert case study [5], Lake Turkana case study [6], sedimentary basins and discovered oilfields and microseepage signals.…”

“…Once at surface, microseepage creates a soil atmosphere containing volatile hydrocarbons that interacts with the soil's particles, minerals and the above vegetation. While the scientific community is still debating on the effects of microseepage on the environment [6], more and more studies propose this phenomenon as marker for the detection of active petroleum systems [7,8,9,10].…”

“…With reference to soil alterations, remote sensing technologies are able to point out some specific markers [6,11,12]. For example, the presence of Kaolinite driven by acidic conditions could be the main clue to follow when studying a very complex geological framework [13].…”

Hydrocarbon Microseepage Potential Area Exploration Using Sentinel 2 Imagery

“…This makes the presence of micro hydrocarbon seepage can serve as a foundation for experts to conduct further exploration activities in the region [5]. Over the years, remote sensing techniques with satellite imagery have been used to detect any indication of such seepage systems [3] [6] [7]. Detection by satellite imagery is carried out through the process of recording the reflectance characteristics generated by HC microseepage symptom [5].…”