The use of reservoir geochemistry in field development has been well established for several years in conventional reservoirs to understand reservoir compartmentalization and fluid property distribution. However, its application to unconventional reservoirs (both source rock and hybrid plays) has been less well-documented and is often more challenging.
When interpreted geochemically, the time series produced fluid carries valuable information that reveals the temporal and spatial variation of the effective drained rock volume (DRV) surrounding horizontal wells in unconventional plays. This dynamic behavior of the DRV is crucial to various field development decisions including vertical landing targets, well spacing and stacking, and completion designs. Compared to other diagnostic technologies (e.g. microseismic, downhole pressure gauges, and fiber-optics) that are reflective of the stimulated rock volumes (SRV), geochemistry-based methods directly measure the produced fluid and therefore reveal the true DRV of the hydraulically-fractured well. ConocoPhillips has successfully deployed time-lapse geochemistry (TLG) for over 5 years across multiple North America unconventional assets, and found that collecting and analyzing fluid samples over time often indicates that drainage heights are dynamic. Here we present an overview of the application of time-lapse geochemistry in assorted North America ConocoPhillips unconventional plays, and show an example application from the Bakken/Three Forks play in the Williston Basin. The use of TLG methodologies for production allocation of oil and water will be presented for a spacing pilot through time, and the implications for field development will be illustrated.
Recent technology advances in horizontal drilling and hydraulic fracturing have unlocked significant resources in the unconventional plays, particularly those in shales and hybrid plays with ultra-low permeability. Since then, the industry has recognized the importance of characterizing the induced fracture network, the extent of which is crucial to the economics of unconventional reservoir development.
