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The Exploited: Ichnologic Analogs for Multi-Lateral Horizontal Oil Drilling in the Early Cretaceous (Albian) Clearwater Formation, Alberta, Canada

Abstract

Over the past three years, the Clearwater Formation oil play in northern Alberta has grown from its infancy into one of the most economically attractive plays in North America. Drilling techniques evolved at Marten Hills as operators experimented to find the most efficient and economical way to exploit the resource. Drilling has evolved from unsuccessful vertical wells, through using short horizontal wells, to finally the current design of closely spaced, multi-lateral horizontal wells. The multi-lateral well patterns bear a remarkable resemblance to those exhibited by the ichnogenera Chondrites and Oldhamia. These analogous approaches to the efficient exploitation of resources have both evolved as a mechanism to survive and thrive in hostile or extreme environments.

Chondritid burrow systems (ichnogenus Chondrites) are generally downward branching (ramifying) deposit-feeding structures and associated with low oxygen, reducing conditions where the trace-making animal exploits a subsurface environment where food resources were presumably low. The low resource environment required the Chondrites tracemaker to adapt and develop a chemosymbiotic relationship with a microbial biomass that is optimized by an efficient subterranean network of branching tubes used to extract maximum solutes from the pore-water. Oldhamia is another Ichnogenus that is interpreted to represent an effective shallow mining behavior for exploiting resource-poor environments. In contrast to Chondrites, Oldhamia branches primarily in the horizontal direction to allow the tracemaker to take advantage of food available on the underside of biomats. As such, spatially efficient mining is requisite for optimization of food resource acquisition. Another interpretation of Oldhamia is that it may be used as an oxygen harvesting structure below photosynthetic biomats, making the analogy to subsurface oil and gas exploitation strategies even more appropriate.

The behaviors demonstrated by the Chondrites and Oldhamia tracemakers are excellent analogs for the oil and gas industry of today, where horizontal and multi-lateral horizontal drilling are being used similarly to exploit thin but resource-rich stratigraphic layers in otherwise resource-poor media. One such parallel between the world of ichnology and the oil and gas world is occurring today in the Early Cretaceous-aged Clearwater Formation oil play in the Marten Hills area of Alberta, Canada.