Quantitative three-dimensional remote digital compositional characterisation of outcrops

The construction of 3D sub-surface geospatial models of onshore basins is a vital aspect of hydrocarbon exploration and is critically dependant on the information derived from the analysis of geological outcrops and borehole cores. Current field-based mapping methods produce very limited datasets which result in significant gaps in structural information with consequent severe effects on the accuracy of geological interpretation. A wide range of remote mapping methods, at a variety of spatial scales, have previously been implemented to resolve geological composition and structure of onshore hydrocarbon basins with limited success. These remote mapping approaches have used a reflectance-based approach covering the entire solar spectrum (VNIR to SWIR). Reflectance-based approaches have a fundamental limitation in that most of the key mineralogical types found in igneous, metamorphic and sedimentary rocks, e.g. chain and sheet silicates, are not identifiable at these wavelengths.

A NERC-funded project, awarded to the applicant, has developed a highly novel, instrument capable of acquiring high spectral resolution remote sensing imagery covering the thermal waverange. This instrument (the MicroFTS) is lightweight, rugged and low-cost enabling it to be deployable in the field on an operational basis. The instrument also has the capability of being mounted in a variety of observation configurations (ground, UAV, aircraft) providing the potential for practical application in a range of fields apart from geology including agriculture, environmental monitoring and civil engineering. The high spectral resolution of the imagery enables a range of key physical parameters to be retrieved remotely directly from the imagery including surface temperature and composition and atmospheric composition.

Emission spectra, covering the thermal waverange, have a number of significant advantages over reflectance spectroscopy including the capability to identify (i) a wide range of minerals not detectable in reflectance spectra; (ii) variations in rock fabric and bulk chemistry and (iii) petrological level mineralogical information. These capabilities enable individual stratum to be classified into specific sedimentological facies and diagenetic types using their diagnostic emission spectral profiles. These classification approaches could enable a high level of sedimentary analysis to be automatically implemented at high spatial resolution, over continuous areas from site-to-basin scales. The ability to automatically resolve individual stratum and stratigraphic sections in borehole cores and outcrops at site-to-basin scales would provide a means of correlating stratum across entire basins enabling sequence stratigraphic analysis and key structural data such as fault throw to be determined and incorporated into geospatial models. These new remote observational datasets would not only provide a significant increase in the amount but also produce new types of observational datasets of the key compositional and structural information required by sedimentary petrologists and basin analysts. At the site scale continuous, complete coverage of compositional and structural features, even across inaccessible localities such as quarry walls, would be a significant new data resource. At the landscape scale the increase in the volume, the improvement in the spatial distribution and the continuous nature of the coverage would be equally as important. These new compositional and structural observational datasets would provide a means of significantly improving the accuracy of analysis of hydrocarbon basins at a fraction of the cost of the overall project budget at locations anywhere in the world. The potential market for the proposed methodology is extensive, global and the industry uptake is likely to be significant and immediate.

Outcomes and Benefits of Project

There will be a number of significant outcomes from the project:

A thorough evaluation of the capability of the MicroFTS, coupled with a TLS and digital photography, to significantly increase the volume and coverage, the level of detail and the three-dimensional characterisation of structural and compositional information retrievable from outcrops and borehole cores.

Development of novel methods to integrate datasets acquired from digital data capture from analogue sources and new field-based datasets.

Potential of a 3D rig, integrating a TLS, ultra-high resolution digital photography and the MicroFTS to acquire imagery of borehole core samples.

A thorough evaluation of capabilities of the MicroFTS imaging FTIR approach to remotely retrieve a wide range of geological information. Specifically:

1. chemical-mineralogical-lithological classified image datasets with specific reference to oil and gas related lithologies, e.g. shale, sandstone, limestone.
2. textures, stratification, bedding, and nature of diagenesis
3. essential structural and stratigraphical details such as fold strike and dips measurements, fault throw values.
4. capability to resolve individual stratum and complete stratigraphic sections across boreholes and outcrops and the potential structural mapping capabilities.

These outcomes will provide a number of significant benefits not only to the oil and gas sector but to a wide range of geologists in both industry and academia.

Classification of the integrated image datasets will enable a high level of sedimentary analysis to be automatically implemented at high spatial resolution, over continuous areas from site-to-basin scales. The ability to automatically resolve individual stratum and stratigraphic sections in borehole cores and outcrops at site-to-basin scales would provide a means of correlating stratum across entire basins enabling sequence stratigraphic analysis and key structural data such as fault throw to be determined and incorporated into geospatial models. These new remote observational datasets would not only provide a significant increase in the amount but also produce new types of observational datasets of the key compositional and structural information required by sedimentary petrologists and basin analysts. At the site scale continuous, complete coverage of compositional and structural features, even across inaccessible localities, would be a significant new data resource. At the landscape scale the increase in the volume, the improvement in the spatial distribution and the continuous nature of the coverage would be equally as important. These new compositional and structural observational datasets would provide a means of significantly improving the accuracy of analysis of hydrocarbon basins at low cost anywhere in the world. The potential market for the proposed methodology is extensive, global and the industry uptake is likely to be significant and immediate.

The low cost, high spectral resolution, and portability of the MicroFTS will provide a step-change in the operational deployability and capabilities of an Imaging FTIR with a significant increase in the potential applications including mapping surface compositions and gas flux analysis. The MicroFTS has the capability of being deployed in the field in a variety of observation configurations (ground, UAV, aircraft) providing the potential for practical application in a range of fields.