Exploitation of natural resources

Context

As known global oil and gas reserves diminish, oil companies are under a great deal of pressure to tap new sources. In the past few years, exploration managers have been looking increasingly to frontier areas offshore, such as the Arctic and South East Asia to supplement existing reserves. Exploration in these frontier areas brings a whole new set of problems, however, as these areas have seldome been surveyed by conventional ship survey methods, and additional problems may exist through harsh environmental conditions, especially in the Arctic. In order to make large scale surveying of as yet unexplored regions as cost-effective as possible, exploration managers are looking to new methods, such as the use of satellite data.

The identification and mapping of terrestrial structures related to hydrocarbon and mineral deposits is the key to many individual applications within geology, such as general geological mapping and mineral deposit location. Ground based surveys can often experience difficulty in the detection and mapping of large scale lineament features which indicate deposits, whereas they are often readily visible from satellite imagery such as SAR due to its side look viewing geometry.

Contents

The information covered here covers applications of ERS, whether marine- or land-based which contribute to the search for minerals and hydrocarbons. These are:

• Marine gravity anomaly for offshore hydrocarbon exploration
• Offshore basin screening for oil seepage
• Identification of terrestrial mineral deposits
  
  
  

Marine gravity anomaly mapping for offshore hydrocarbon exploration

Illustration: Free air gravity anomaly map of the Gulf of Mexico produced using ERS data (Courtesy: Satellite Observing Systems)

Conventional methods of surveying an offshore area are gravity, magnetic and seismic surveys by ship, which are labour intensive and expensive especially on a regional scale for the purposes of preliminary surveying. Gravity anomaly maps derived from altimetry from ERS and other satellite missions provide an alternative to these expensive ship surveys for a regional overview of the potential existence and position of viable deposits. The expense involved in such a survey is so vast that even small percentage savings on current operational costs make the use of satellite-derived alternatives very attractive to industry.

The ERS-1 Geodetic Mission, completed in 1994, provides geographically uniform coverage up to latitudes of 82N, of a relatively high spatial resolution dataset for deriving gravity anomaly.

Basin screening for natural oil seepage

Distribution of possible sea slicks derived from SAR data overlaid on a map of free air gravity anomaly also derived using ERS data (Courtesy: Nigel Press Associates)

Natural oil slicks on the sea surface due to seepage arising from sub-sea hydrocarbon deposits can be identified and analysed using ERS SAR images. It requires a considerable volume of data as the location of the oil-bearing structures must be studied using data over a long time series. However, combined with satellite-derived gravity maps which reflect the regional structure of the lithosphere, the economic potential of a particular basin for hydrocarbon exploitation can be estimated. The financial implications in the provision of such a service are considerable. Savings in time and expense realisable using these methods provide a potential market estimated to be in the region of US $5-10 million per annum worldwide.

Identification of terrestrial mineral deposits

There is already a high degree of acceptance of the use of optical EO data in geological mapping applications due to the logistics and economics involved in locating features such as base metal deposits or hydrocarbon reserves. Unique properties of SAR data are now being exploited to aid further the exploitation of natural resources by detecting the lineament features and anti-cline structures which may indicate the presence of mineral deposits. Due to it's side look viewing geometry SAR data is particularly effective in identifying these geological features, and in detecting them even when masked by vegetation.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry