Close to 70% of assets world-wide are associated with regional basement architecture

An understanding of how the basement architecture is influenced by basement structure provides the foundation onto which sediment fill is deposited. Depth-to-basement, basin architecture, and basement structure and composition beneath sedimentary basins often remain poorly understood because the extent of exposed basement outcrop is often limited, only a few wells intersect basement, and the basement horizon often cannot be resolved using seismic data.

Eslan Labs is currently engaged in gravity and magnetic interpretation studies to improve our understanding of how the basin architecture is influenced by both the crystalline and “economic” basement in petroleum regions world-wide, generating the products:

This work has developed alternative methodologies to define the crystalline and economic basement  so it can be used as a framework for predictive basin analysis when other datasets are unavailable.

Regional tectonics influence how the crust deforms and variations in basement architecture, strength, composition and structure – all factors affecting the generation of hydrocarbon resources

 

These studies complement seismic exploration, and are applicable in different tectonic settings. Gravity and magnetic derived basement architecture and structural interpretations provide unbiased interpretation and a means to fuse geological, magnetic basement, and seismically-derived sedimentary structure.

Basin architecture and structure is important because a high correlation between crystalline basement structure and sediment draping explains the relationships between basement architecture and oil and gas distribution

Multi-Source Data Fusion

Eslan Labs is assessing the prospectively of frontier areas of basins across the middle East, central Asia, Caucusus, and north and south America as part of a world-wide evaluation.

New data are merged with existing datasets and the final compilation provides a consistent onshore/offshore dataset that covers the studied regions, and is the primary dataset used for our study – useful where seismic data is unavailable or no basement reflector can be resolved. Insights into basement architecture and composition are provided from basement outcrop onshore, basement intersections in wells, and academic research publications provide sampling surveys conducted across the region.

Depth to Basement

Sediment thickness is a fundamental factor in assessing the architecture, evolution and petroleum prospectivity of a basin. Deep basin architecture may be difficult to resolve in some seismic datasets.

Eslan Labs approach to modeling depth to magnetic basement uses several complementary modern magnetic methods estimates, and additional geological and geophysical data (such as well information, surface outcrop, gravity and seismic interpretations) are integrated into the depth to basement workflow which results in a more geologically robust depth-to-basement model.

The depth to crystalline basement typically highlights the main sub-basins and structural highs and indications of total sediment thickness. A comparison of the depth-to-basement with the DEM topography often provides further insight into the total thickness of early syn-rift/pre-rift sediments, beyond that resolved using seismic data alone.

The crystalline basement architecture frameworks defined in this study demonstrates the application of basement studies for predictive basin analysis in the context of petroleum exploration in rifted margin settings. The methodologies described here may be applied to other regional geological and exploration activities in many different geographic and tectonic settings.

This initiative is providing a new regional view and common patterns of the simplified basement lithology, geometry and variation of basement across many of the world’s basins based on the integration of numerous geophysical and geological datasets.

Basement Architecture and Surface Structure

It is important to Include the crystalline basement architecture into basin modeling in order to determine heat flow, maturation analysis and hydrocarbon migrations, and such a basement surface should be derived independent of a seismically-derived surface.

Gravity and magnetic derived basement architecture interpretations provide unbiased interpretation and a means to integrate geological structure, magnetic basement structure, and seismically-derived sedimentary structure.

Basement Structure and Composition

New interpretive maps of basement architecture, composition and structural fabric can be used to better understand the nature of basement across a region.

Basement architecture, structure and composition have been constructed through the integrated interpretation of all available geological and geophysical datasets, including outcrop, wells, geochronology, seismic, gravity, magnetic and bathymetry datasets

Direct geological observations (outcrop, wells or dredge samples) are compared with potential field characteristics to identify relationships between observed basement composition and rock properties (density or magnetic susceptibility).

Typically, there are correlations between observed structural fabrics and equivalent trends in the potential field data, and between the observed seismic characteristics. The potential field data are used to predict basement terrain distribution, basement composition and structural fabric in areas where no other datasets are currently available.

Basement architecture is mapped using basement outcrop, potential field, multispectral imagery and DEM data. The mapped structures include basement faults, dikes and structural trends and lineaments that can be identified in the potential field data. Basement trends associated with the younger orogens have a profound affect on Late Jurassic‒Early Cretaceous margin development. This map highlights potential variations in radiogenic basement-derived heat flow which might have influenced the thermal evolution of the basin and hence petroleum source rock maturation.

For example, younger fracture zones typically correlate with a significant change in basement structural trend. In addition, a linkage is evident between basement fabric orientation and basin geometry implying basement structures have significantly influenced basin evolution and patterns of sediment deposition throughout time.

Deeper Structure

New tectonic models and recent basin reconstructions also take into account the Moho discontinuity because a complete earth model requires both basement and Moho structural horizons in order to build viable interpretations. Gravity and magnetic data reveal much deeper structure than conventional reflection seismic data because they reveal lateral variations in subsurface density and magnetic susceptibility, respectively, indicating depth of source body.

Modern exploration workflows include the characteristic types of crust: craton, platform, orogenic belt, continental rift, marginal, and ocean basin.

They constrain upper crustal thickness and basement composition, magnitude of crustal extension, and the upper crustal contribution to heat-flow for basin modeling and so the basement architecture can be characterized  by crustal types based on magnetic basement structure integrated with gravity data and geological outcrop.

A high correlation between basement structure and sediment draping explains the relationships between basement structure and oil and gas distribution.