Outcrop and modern analogues have long had a key role in improving our understanding of subsurface reservoirs. Data collected by traditional mapping, logging and the use of scaled drawings/photo panels, have provided hundreds of reservoir analogue datasets which form the basis for our understanding of facies architecture. However, much of these data are buried in libraries and is hard to access and utilize on a day to day basis.
Since the start of the 21st century there have been significant advances in data collected technology, especially with the advent of virtual outcrops (VO). A VO is a 3D computer realisation of an outcrop that allows the user to view the outcrop from any direction and also to make accurate, geometrically constrained measurements of dimensions, geometry and the spatial location of architectural elements. Virtual outcrops are revolutionising analogue studies.
The development of terrestrial laser scanning (LiDAR) in the early 2000’s heralded the dawn of practical virtual outcrop work. In the last 10 years we have seen rapid improvements to the basic, ground based LiDAR methodology such as mounting the system into a helicopter so that it can be flown along the outcrop allowing very rapid collection of large (10s km) datasets from the most remote outcrops and, combining the laser scanner with ground based hyper-spectral scanning to map mineralogy and lithology automatically. The most recent developments include the use of Unmanned Aerial Vehicles (UAV or drones) coupled with a recent resurgence in photogrammetry. UAVs provide a relatively inexpensive platform for the collection of data similar to the heli-lidar for a fraction of the cost. Virtual Outcrops can be interpreted manually, but recent advances in image recognition software also allows for the automated extraction of geometric data from the VO.
The advent of large volumes of freely available remote sensing data (GoogleEarth etc) has also lead to a parallel resurgence in the use of modern systems as reservoir analogues. Recent studies have led to several paradigm shifts in our understanding of the preservation of depositional systems, such as the concept of Distributive Fluvial Systems (DFS), which in turn have significantly altered our view of reservoir architecture and added significant volumes of information on sandbody geometries to our datasets .
These advances are fundamentally changing the way we build reservoir models. In the 21st Century, every geologist who is struggling to build a model can easily find suitable analogues (modern and ancient) from their desktop. They can go on a Virtual Fieldtrip and extract geometric data from suitable outcrops; they can fly directly to high quality satellite imagery of an analogous modern system and view the spatial relationships between the various sedimentary bodies that comprise the reservoir elements. The reservoir analogue studies and databases of the 21st Century are a far cry from what was available even 20 years ago which is fortunate because understanding the complexity in our reservoirs is ever more important.