Kinematics as a Key to Unlocking Plays
Applied to continental areas, kinematic analysis provides map-view palinspastic (predeformation) reconstructions analogous to balancing and restoring cross-sections in the vertical plane. A more rigorous reassembly of continental blocks prior to deformation yields insights into subtle basin-forming processes that influence hydrocarbon systems. For example, more accurate plotting of paleofacies for times prior to deformation is of vital importance in studies of reservoir strata.
Consider the simple steps for restoring the northern Andean ranges and basins for Early Oligocene and earlier time, prior to most ‘Andean’ deformation. A reference frame is needed to begin: we assess motions relative to the Guyana Shield, the stable interior of South America. The inset on Figure 2 shows a ‘vector nest’ summarising key displacements in the area, allowing us to estimate displacement in complex areas (for example Eastern Colombia of Colombia) using better-known displacements (for example Merida Andes, Santa Marta Fault). Provided we have correctly identified the main blocks, and that only minor vertical axis rotation of these blocks has occurred, all motions must be consistent with this closed network, allowing us to identify cryptic, usually strike-slip, deformation.
Figure 2
We can now draw a pre-Andean (i.e. pre-Late Oligocene) palinspastic reconstruction of the northern Andes (Figure 2), showing predeformation positions of present-day latitude and longitude lines, and can plot, for example, Eocene formations, sedimentary facies and paleoenvironments on the reconstruction in order to build accurate models of regional Eocene depositional systems. The resulting depositional models can be compared more meaningfully with modern analogues and analysed for implications for reservoir potential and migration pathways, such as sand body orientation, sinuosity, flow direction, sediment provenance and maturity. Similarly, we can reconstruct the Cretaceous basin, allowing us to assess source rock character, quality and original areal extent.
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