Energy Products
Remote Prospector™
Remote Geochemical Exploration from Satellites
AAI's Remote Prospector™ line of map products represents a major breakthrough in onshore oil and gas exploration. Advanced image processing technologies are capable of "seeing" certain specific ground materials in earth satellite imagery that have traditionally served as surface geochemical indicators of sub-surface hydrocarbon reservoirs. Previously these were typically only detectable in samples collected during costly field visits, but now they can be found without ever having to visit the site. Areas can be searched more thoroughly and systematically, and at a tremendous savings in time and cost. Furthermore, the wide area coverage of satellite images allow vast areas to be efficiently searched, and narrowed to specific high-prospect areas where follow-up field visits and geophysical surveys can be concentrated at substantially lower risk.
The surface geochemistry approach to oil and gas exploration has been used for more than 30 years. It consists of a search for surface occurrences of identifiable hydrocarbon-induced changes resulting primarily from micro-seepage of hydrocarbons from traps at depth. Surface micro-seepage refers to the leakage of light volatile hydrocarbons from their traps, and their seepage toward the surface along fractures and other migration conduits. The hydrocarbons induce geochemical changes along the migration pathway that ultimately result in the creation of several geochemical anomalies on the surface, some of which are visible from space. The visible ones include local anomalies in vegetation cover and certain modified soil properties. The latter include locally concentrated red iron oxide, bleaching of the surface material, and locally concentrated carbonate deposits. Occasionally macro-seepage deposits, consisting of oil and paraffin dirt, will accompany the micro-seepage features.
Other vendors have attempted to detect surface micro-seepage features in satellite imagery and use them to prospect for oil and gas. They have met with mixed success, however. Unlike Remote Prospector™, most of their products are based on detections of image "anomalies," which typically represent the net effects of complex and unknown intermixed land cover materials and phenomena. In most cases these "anomalies" are dominated by the presence of stressed vegetation and vegetation variants, which are often unrelated to hydrocarbon effects. Since they often are unable to deduce from the imagery alone what specific materials or phenomena produce the "anomalies," their maps of "Hydrocarbon Intensity" or "Oil and Gas Potential" typically rely heavily on use of additional time-consuming and costly independent field measurements.
In contrast, Remote Prospector™ detects and reports the locations of three highly specific materials that are stable and universal surface geochemical indicators of hydrocarbon micro-seepage. They include 1) a special form of concentrated red iron oxide; 2) bleaching of the surface material; and 3) carbonate deposits. Macro-seepage of oil and "paraffin dirt" can also contribute. These are explicitly and simultaneously retrieved from the image data at sub-pixel scales and reported, so they can be used and evaluated on their own. They are like traditional geochemical or geophysical field data, which can be used to make meaningful educated assessments of leads and prospects. Also because they are stable and universal indicators, they provide the opportunity to prospect virtually anywhere on the globe. Up to now, field sampling has been the only method that could effectively detect and utilize these surface geochemical indicators for prospecting. Remote Prospector™ employs AAI's highly advanced Mixed Material Classifier, iCee™ Atmospheric Correction, and Material Identifier technologies, which for the first time allow these materials to be explicitly and independently identified in satellite imagery even when they represent as little as a few percent of the land cover in an image pixel. Unlike the approaches being used by the other vendors, stressed and sparse vegetation anomalies are purposely not included in the standard Remote Prospector™ Survey product. Sparse vegetation is, however, implicitly included by requiring the three primary indicator materials to be exposed on the surface (not obscured by vegetation) to a sufficient degree to be detectable from the satellite. By not including explicit detections of stressed or sparse vegetation in the indicator set, the potential for confusion with vegetation variants and the many other non-hydrocarbon sources of stress is significantly decreased.
Finally, because of the hands-off and fully remote nature of the technologies used to generate the Remote Prospector™ products, the standard Survey Product maps can be provided within a surprisingly short period of time from a request. Typical turn-around times are under 10 days for the initial request, and less than a week for subsequent requests from the same Landsat Thematic Mapper image(s). This is in contrast to the several month or longer turnaround times that are typically experienced in the industry. They are also surprisingly affordable, significantly lowering risk and reducing cost barriers.
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Remote Prospector™ Illustration 1:
Vegetated Domestic Setting
The ellipses were based on the spatial distribution of the filtered geochemical indicators alone. No other information was used. The area inside of the orange ellipse represents an area of concentrated microseepage, and is a high-probability candidate location for a subsurface oil or gas reservoir. The two red ellipses indicate areas of relatively greater apparent leakage.
To check how well Remote Prospector™ performed at this site, the reported locations of the filtered geochemical indicators could be compared to the registered locations of oil and gas wells in the region. The comparison is shown in the figure below. The product successfully identified a large currently productive gas field that spanned the full area of the outer (orange) ellipse, and extended beyond the borders to the east and northeast. The two inner ellipses (red) successfully captured areas of relatively high production, based on the well data. The paucity of filtered geochemical indicators northeast and east of the ellipse in spite of high well production there indicates that the reservoir was apparently well capped in that area.
Use of the clusters of detected geochemical indicators to delineate hydrocarbon reservoirs must be done with caution. This is especially true when the geology is complex. The migration pathways are often generally vertical, but sometimes they can occur along dipping lateral carrier beds or barrier interfaces, such as a salt dome, cross-cutting bed, or similar formation. In the former situation (generally vertical pathway) the geochemical indicator features will generally be directly above the reservoir, while in the latter case (lateral pathway) they can be laterally displaced from the reservoir.
To help the targeting and risk assessment process, the Remote Prospector™ results are typically presented on three contextual base maps (not shown for this illustration to protect the rights of the customer). For domestic locations, the first is a standard 1:24,000 scale topographic base map to provide the topographic and cultural feature setting. The second is an orthophoto base map at the same scale to provide the land cover and land use setting. The third is a shaded relief base map from which key structural information can be inferred from the landforms, such as local fracture orientations (lineaments), fracture densities, and doming. Viewing the geochemical indicators in the context of these three classes of background setting can greatly facilitate the targeting and risk assessment of drilling locations. For non-domestic locations, the specific contextual base maps provided are subject to availability and may be different.
In the illustration above, the geology inferred from the contextual base maps (not shown) showed no compelling evidence that the clusters of geochemical indicators were laterally displaced from the trap. In this instance, the ellipses could have been effectively used as drilling "targets."
Remote Prospector™ Illustration 2:
Arid Non-Domestic Setting
An illustration of performance in a very different and challenging setting is shown below. First, there is virtually no vegetation, removing the principal source of stressed-vegetation "anomalies" relied upon by the other image-based approaches. Second, iron oxide is a major pigment affecting the spectral properties of the surface material in this region. This added background level of iron oxide would significantly interfere with the detection of local occurrences of the highly concentrated form using other technologies, including most ground survey analysis approaches. There are also abundant carbonate and salt materials present, which can strongly interfere with the discrimination of microseepage-induced carbonate and bleached material geochemical indicator materials using other image-based and ground survey analysis technologies. Third, the location is in a very remote and isolated non-domestic setting, making it logistically difficult and very expensive to obtain collateral geophysical data, particularly the ground measurements the other approaches rely upon.
The technologies that form the basis for Remote Prospector™ make the product robust across the diversity of settings in which the process might be used. The combined iCee™, Mixed Material Classifier, Material Identifier, and spatial filteringcore technologies utilized by Remote Prospector™ are able to make both the necessary discriminations and physical associations over the relevant spatial scales, even in such unfavorable background settings. Remote Prospector™ also provides a wide-area contextual perspective that can be critical to meaningful assessment of leads and prospects in remote and inaccessible regions where the geology may not be well understood.
In the next figure the detected hydrocarbon microseepage indicators are shown on a shaded relief base map, which helped deduce underlying structure, such as local fracture orientations (lineaments), fracture densities, doming, and barrier interfaces. Also shown are four test well locations, selected by the customer based on previously acquired airborne geophysical data.
The patterns of detected geochemical indicators revealed distinctly different modes of hydrocarbon microseepage in the southwest and northwest quadrants. In the southwest quadrant, diffused wide area clusters of geochemical indicators occurred in a structurally complex setting. This can be seen more clearly in the enlarged view below, where the complex structural control is evident. Also evident is an apparent absence of geochemical indicators in areas dominated by the dunes, suggesting that additional areas of microseepage could potentially be obscured by the dune deposits.
In the northwest quadrant, the hydrocarbon microseepage appeared to be dominated more by barrier interface flow along the sandstone formation boundaries. This can be seen more clearly in the enlarged views on the shaded relief and geologic base maps below. Many of the geochemical indicators occurred within channel and floodplain alluvium deposits (cream colored unit in the geologic base map), clustered along the boundaries of the sandstone formations (green and dark brown units in the geologic base map). The base maps revealed these sandstone formations to be the primary sources of topographic relief in this region, and the gross orientation characteristics of the dipping beds could be discerned using the shaded relief base map. Many of the clusters of detections are in patterns consistent with barrier migration of the hydrocarbon microseepage along the surface of the dipping formation (primarily the green unit in the geologic base map), forcing it to emerge from the channel and floodplain alluvium deposits at the channel termini and floodplain/sandstone formation boundaries. Targeting in the northwest quadrant would be a little more problematic than in the southwest quadrant, since the microseepage features could potentially be significantly offset from the reservoir.
Turning the focus to the test wells, a more detailed view of the complex terrain in the vicinity of the test wells can be seen in the standard Remote Prospector™ Survey Product figures below. The first figure shows the hydrocarbon microseepage indicators and four test well locations on an image base map at the spatial scale of the standard non-domestic Survey Product. The image base map provided the land cover and land use setting in the immediate vicinity of the Test Well locations. Note that each of the detected geochemical indicators either fell along an apparent boundary between material units and/or along a fracture trace in this structurally complex terrain. This indicates that unit boundaries and fractures were likely the dominant forms of microseepage pathway in this region.
On a Shaded Relief Base Map.
Here the fracture traces coinciding with some of the geochemical indicator locations could be discerned.
Geologic Base Map, showing the surface geologic units in the area of coverage. The base map revealed that the geochemical indicators in the vicinity of the test wells were largely on the older alluvium substrate between the more recent dune and dry lakebed deposits. This suggests that the observed spatial distribution of geochemical indicators may have been influenced by obscuration by the more recent mobile dune and dry lakebed materials. This needs to be taken into account when estimating the size and location of reservoirs, and assessing the targeting decisions that led to the test well placement.
All four test well locations were embedded within the larger-scale cluster of geochemical indicators in the southwest quadrant of the full image described above, and hence each test well is in an apparently generally favorable location. At the smaller spatial scale of the standard non-domestic Survey Product, Test Wells 1-3 were each in close proximity to small clusters of geochemical indicators, while Test Well 4 was not. From the image base map, it can be seen that Test Well 4 sits within the interior of a relatively small unit, with nearby boundaries and fracture traces that are void of geochemical indicator features. Although the reservoir may simply be better capped there, the results suggest that Test Wells 1-3 may be in more favorable locations.
Remote Prospector™ Second Look Product
An optional "Second Look" product is also available to expand on the basic "Survey Product" information, if needed. Significant additional retrieved information is left out of the Survey Product, because it is useful only as supplemental information in local context. This includes:
- Wide area low intensity seepage. Scattered low intensity geochemical indicators in the vicinity of the medium and high intensity features reported in the Survey product can sometimes help to further delineate reservoir fields in areas where the reservoir may be better capped.
- Geobotanical anomalies. Any of several geobotanical anomalies can appear in an area of hydrocarbon microseepage. These can take the form of vegetation sparseness, species differences, and stress effects. These can be helpful when considered in the context of the geochemical indicator locations, enabling assessment, for example, of whether seeps are active or passive, or whether reservoirs have redistributed.
- Special requests. Other information can be retrieved from the imagery that can further help to evaluate exploration leads and prospects developed from the Survey product. These can include, for example, exposures of specific soil horizons and outcrops, among other features, supplied by special request.
Note that the "Second Look" information is derived from the same image as the Survey Product information. It does not rely on time-consuming, expensive, and inherently error-prone registration of data from different sources. Although the latter can be done, if requested, the ability to use a single data source is a significant advantage.
Underwater Hydrocarbon Seep Surveys
Another in AAI's line of remote energy exploration products is a wide-area survey product for natural underwater hydrocarbon seeps. Commercial satellite imagery is searched for bottom cover, water column, and water surface features consistent with natural underwater oil and gas seeps. Among the bottom cover features sought are natural tar mounds, black sulfide-rich sediments, and eroded sediment exposures along fissure traces. Water column features sought include diffuse to effervescent plumes of bubbles of escaping natural gas, and plumes of dissolved organic carbon from dissolving oil droplets and films on the bubble surfaces as they rise through the column. Water surface features sought include intact oil slicks of varying thickness and stages of weathering, dispersed floating masses of tar balls and mousse, as well as associated plumes of dissolved organic carbon from weathering of the surface oil.
An illustration is shown in the sequence of figures below for a remote tundra location. This is an area of suspected hydrocarbon seeps, but it has been logistically impractical to explore using traditional ground-based methods. The first figure shows the natural color image, revealing an extensive swarm of lakes of varying size. The second figure shows the retrieved bottom topography of each water body, reported as depth relative to the surface of each water body. Depths range from 5m to less than 1m, and the bottom topography reveals structural detail that is key to understanding the underlying geology of the site.
In the next figure is shown an enhanced natural color image of the retrieved lake bottom materials. The bottom materials appearing medium to dark blue in this image have spectral properties consistent with natural tar mounds and black sulfide-rich sediments associated with seepage. Of particular interest are the areas enclosed within the ellipses, where the lake bottoms appear to be dominated by these materials. Also of interest are apparent sedimentary layer exposures of the material, indicated by the red arrows.
In the next figure is shown the image-retrieved concentration of colored dissolved organic carbon. The three ellipses from the bottom material figure above are included for reference. Note that some of the same lakes with suspected seepage-related bottom materials also have relatively high concentrations of CDOC, suggesting ongoing seepage in these areas. There are also plumes of CDOC to the north, indicated by the red arrows, which are in the vicinity of the sedimentary layer exposures highlighted in the bottom material figure above. These features are consistent with persistent hydrocarbon seeps at these locations.
In the next figure is shown a zoomed-in view of a cluster of lakes showing interior suspended sediment plumes consistent with agitation by macroseepage of gas (red arrows). Edge occurrences of enhanced suspended sediments occur in many of the lakes. There the water is shallow, and wind-driven agitation kicks up bottom sediments. Interior plumes are different, and require a different source of bottom disturbance such as escaping bubbles of gas. A zoomed-in view of the CDOC concentrations for these two lakes follows. The accompanying plumes of CDOC are consistent with dissolving oil droplets and films on the bubble surfaces as they rise through the column.
AAI's line of unique energy products include a remote wide area shallow water bathymetric mapping product to support shallow water geophysical surveys. Accurate depths and bottom cover materials are retrieved automatically from satellite imagery alone, even in near-shore waters where complex water quality characteristics and shallow depths have often foiled such remote mapping attempts in the past. No ground truth or other external information is required, allowing depths and bottom cover characteristics in out-of-date or uncharted waters to be mapped without having to visit the site. Depth and bottom cover characteristics are reported with a level of topographic detail limited only by the pixel size of the sensor (e.g., 2.5m ground sample distance for commercial QuickBird imagery, and 30m GSD for Landsat Thematic Mapper imagery). For a detailed description see our Substrate Mapping page.
Whether your interests are onshore or offshore, AAI's remote exploration products can provide a highly cost-effective and quick turn-around means for assessing leads and prospects. For remote and inaccessible regions, these products may be the only practical means for obtaining an initial assessment. Contact us if you have an area you would like to have assessed.