论文部分内容阅读
Thermal maturation and petroleum generation modeling of shales is essential for successful exploration and exploitation of conventional and unconventional oil and gas plays. For basinwide unconventional resource plays such modeling, when well calibrated with direct maturity measurements from wells, can characterize and locate production sweet spots for oil, wet gas and dry gas. The transformation of kerogen to petroleum is associated with many chemical reactions, but models typically focus on first-order reactions with rates determined by the Arrhenius Equation. A misconception has been perpetuated for many years that accurate thermal maturity modeling of vitrinite reflectance using the Arrhenius Equation and a single activation energy, to derive a time-temperature index(∑TTI ARR), as proposed by Wood(1988), is flawed. This claim was initially made by Sweeney and Burnham(1990) in promoting their “Easy R o” method, and repeated by others. This paper demonstrates through detailed multi-dimensional burial and thermal modeling and direct comparison of the ∑TTI ARR and “Easy R o” methods that this is not the case. The ∑TTI ARR method not only provides a very useful and sensitive maturity index, it can reproduce the calculated vitrinite reflectance values derived from models based on multiple activation energies(e.g., “Easy Ro”). Through simple expressions the ∑TTI ARR method can also provide oil and gas transformation factors that can be flexibly scaled and calibrated to match the oil, wet gas and dry gas generation windows. This is achieved in a more-computationally-efficient, flexible and transparent way by the ∑TTI ARR method than the “Easy R o” method. Analysis indicates that the “Easy R o” method, using twenty activation energies and a constant frequency factor, generates reaction rates and transformation factors that do not realistically model observed kerogen behaviour and transformation factors over geologic time scales.
Thermal maturation and petroleum generation modeling of shales is essential for successful exploration and exploitation of conventional and unconventional oil and gas plays. For basinwide unconventional resource plays such modeling, when well calibrated with direct maturity measurements from wells, can characterize and locate production sweet spots for The transformation of kerogen to petroleum is associated with many chemical reactions, but but typically scales on first-order reactions with rate determined by the Arrhenius Equation. A misconception has been perpetuated for many years that accurate thermal maturity modeling of vitrinite reflectance using the Arrhenius Equation and a single activation energy, to derive a time-temperature index (ΣTTI ARR), as proposed by Wood (1988), is flawed. This claim was initially made by Sweeney and Burnham (1990) in promoting their “Easy R o” method, and repeated by others. This paper demonstrates through detailed mul ti-dimensional burial and thermal modeling and direct comparison of the ΣTTI ARR and “Easy R o” methods that this is not the case. The ΣTTI ARR method not only provides a very useful and sensitive maturity index, it can reproduce the calculated vitrinite reflectance values derived from models based on multiple activation energies (eg, “Easy Ro”). Through simple expressions the ΣTIR ARR method can also provide oil and gas transformation factors that can be flexibly scaled and calibrated to match the Oil, wet gas and dry gas generation windows. This is achieved in a more-computationally-efficient, flexible and transparent way by the ΣTIA ARR method than the “Easy R o” method. Analysis indicates that the “Easy R o ”method, using twenty activation energies and a constant frequency factor, generating reaction rates and transformation factors that do not realistically model observed kerogen behavior and transformation factors over geologic time scales.