Abstract

Technology has unlocked thermally mature source rocks, but not all source rocks have been economical plays for reasons relating to inherent source rock attributes, drilling and completion issues, well costs, production difficulties, and fluctuating hydrocarbon prices. Source rock plays have also evolved into lower risk plays, but not risk free plays (Fig. 1). Numerous companies continue to exploit these unconventional reservoirs for both gas and liquids with variable results. This variability will likely grow within North America because many of the top tier source rocks in North America have been tested and riskier and/or lesser known source rocks are now being targeted. Lessons from North American plays has been translated internationally where other key challenges such as infrastructure, water availability (Fig. 2), and other factors are hindering the exploration and development of these plays.

Many universal screening parameters used in industry (i.e., thermal maturity, thickness, TOC, and clay) have helped companies quickly access these plays at different entry times based on their surface and subsurface risk tolerance. These basic parameters are not always straightforward. Thermal maturity is a key element used to predict the desired in-situ hydrocarbon phase as long as migration has not occurred. Localized-to-subregional perturbations (e.g., volcanics) are commonly underappreciated and the issue of merging various maturity indicators is not trivial (Fig. 3). Thickness is critical for landing laterals into source rocks with good hydrocarbon saturation, but if the entire thickness is not pay (Fig. 4) or cannot be stimulated via hydraulic fracturing, well results can be very disappointing. High TOC is a universal attribute of a good source rock, yet not all organic material is created equal. TOC is a measurement of quantity but does not provide an estimate quality. Particular plays, such as the Point Pleasant, have very high hydrogen indexes, which indicate it will be able to compete with other source rock plays with higher TOCs. Vertical and horizontal changes in TOC and kerogen type are also commonly difficult to map during the entry phase of the new or emerging play. Clay is also a common industry screening criteria, but the distribution of clay within the reservoir can impact the effectiveness of hydraulic fracturing and proppant along with the general water saturation in the source rock.

These basic parameters mentioned above are used to assess resource density for a given play, however high resource densities do not necessarily mean productive or economic fairways (Figs. 5 and 6). Production is driven by deliverability and economics are mainly driven by rate, hydrocarbon type, ultimate recovery, and costs (e.g., access, appraisal, development, and market price). Ultimately a high OGIP source rock is a great place to start, however this does not preclude the play from failing. Further technological advances may be needed to unlock these types of production challenged source rock plays.

URTeC 1581891

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