AAPG Annual Convention and Exhibition

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Assessing Oil-In-Place and Oil Mobility in Liquid Rich Unconventional Resource Plays Using Multi-Step Thermal Extraction

Abstract

Assessing the total volume of in place oil and proportion of oil that is producible with completions enhancement are two critical measurements in evaluating Liquid Rich Unconventional well and play economics. This talk examines a thermal extraction procedure developed as a rapid and cost effective method which examines drill cuttings and core material to assess liquid rich unconventional resource oil-in-place (OIP) and oil mobility (producibility). Our MultiStep Thermal Extraction-Flame Ionization Detection System (MiSTE-FID) uses high resolution thermal extraction to sequentially liberate in-situ hydrocarbon and non-hydrocarbon components from fine grain unconventional reservoir rock samples. The thermal extractor is coupled to a flame ionization detector (FID) by a short uncoated capillary column to generate a high resolution thermal extraction profile (thermogram). The thermogram character (peak shape, distribution, and height) and maximum temperature response for each major fraction is examined to evaluate OIP and mobility. The optimal thermal extraction program (starting temperature, ramp rate, isotherms, and ending temperature) has been developed after extensive experimentation with selected unconventional reservoir rock samples under varying conditions and rock types. Two MiSTE-FID oil mobility ratios have been defined to quantify in-situ fluid mobility characteristics: Mobility Ratio 1 = P350°C /P200°C and Mobility Ratio 2 = P200°C /(P250°C + P300°C + P350°C). The MiSTE-FID method captures the conventional programmed pyrolysis S1 as well as free and adsorbed hydrocarbon and non-hydrocarbon compounds which spill over into the S2 kerogen cracking peak. MiSTE-FID analysis is not a simple thermal distillation but includes matrix interactions which enhances the compound separation into more and less mobile oil fractions. Early results indicate MiSTE-FID can be used as a cost effective screening tool in the field or laboratory to assess OIP and oil mobility in liquid rich unconventional resource plays.