“Sweet Spot” Identification and Optimization in Unconventional Reservoirs

Abstract

Correct identification of area or zone of maximum commercial productivity, or the “sweet spot” for unconventional reservoirs requires a thorough understanding of three different reservoir Quality factors: Organic Quality (OQ), Rock Quality (RQ), and Mechanical Quality (MQ). Each of these factors has several individual components that must be measured and quantified. OQ is comprised of the type and maturity of the organic material and the current storage capacity of the organics. RQ, the traditional properties of conventional reservoirs, is the thickness, porosity, permeability, saturation plus mineralogy. MQ is both brittleness and stiffness (which have various indices) and measurements of the stress fields and pressure regimes.

The “sweet spot” is the intersection of these Qualities for the optimum production under a set of foundational conditions. These foundational conditions are 1) Proper regulations and environmental management, 2) Sufficient fiscal environment, and 3) Fit for purpose operations.

Many previous attempts of “Sweet Spot” classification have only focused on reservoir parameters and have not included necessary economic and operational factors. Unconventional reservoirs are a complex interplay between twenty reservoir variables, fourteen completion variables, and five to ten economic and environmental variables. Proper field management requires optimization, in four dimensional space, of all variables.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018