Some E&P Strategies In Low-Perm Systems

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Geologists Shanley, Robinson and Cluff have developed some conclusions and future directions for exploration of and production from low-permeability systems:

  • Exploration efforts in low-permeability settings must be deliberate and focus on fundamental elements of hydrocarbon traps.

    "Improvements in completion and drilling technology will allow well identified geologic traps to be fully exploited, and improvements in product price will allow smaller accumulations or lower-rate wells to exceed economic thresholds, but this is true in virtually every petroleum province," they say.
  • Petrophysics is a critical technology required for understanding low-permeability reservoirs.
  • Low-permeability reservoir systems like those found in the Green River Basin are not examples of "basin-center" or "continuous-type" accumulations, nor are they a unique type of petroleum system.

    "We suggest that the only truly ‘continuous-type’ gas accumulations are found in hydrocarbon systems in which gas entrapment is dominated by adsorption, such as coalbed methane, or where the reservoirs are in close juxtaposition with their source rocks," they wrote.
  • Resource assessments of these regions have assumed a continuous, recoverable gas accumulation exists across a large area locally interrupted by the development of "sweet spots."

    "Our work suggests, however, that this viewpoint is at odds with the reservoir characteristics of low-permeability reservoirs, and we find little support for this model," they wrote.

    Significant production is dependent on the presence and identification of conventional traps, they believe; existing resource estimates, therefore, are likely overestimated.
  • Resource assessments in these low-permeability "basin-centered" regions must recognize the reservoir properties inherent to these rocks and should integrate the necessary concept of source, trap, seal, migration and charge, and be conducted in a manner consistent with the assessment of conventional oil and gas systems.

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