--> Integration of Sequence Stratigraphy, Petrophysics and Geomechanical Analysis for Planning and Design of Shale Gas Reservoir Stimulation: A Cooper Basin Case Study

International Conference & Exhibition

Datapages, Inc.Print this page

Integration of Sequence Stratigraphy, Petrophysics and Geomechanical Analysis for Planning and Design of Shale Gas Reservoir Stimulation: A Cooper Basin Case Study

Abstract

Over the last decade, there has been an industry wide shift to unconventional resources with shale gas being the most appreciable. This change can be attributed to an increase in energy demand, depletion of mature conventional reservoirs and technological advancement. It is well established that organic-rich shales exhibit diverse mineralogical composition, organic matter content and effective stress. This characteristic can influence not only the distribution of pores and hydrocarbon saturation, but also the completion quality. In this situation, it is important to predict the reservoir response to fluid injection and establish an accurate understanding of the reservoir quality and geomechanical properties. The variability of reservoir response to fluid injection has led to the utilization of “brittle” and “ductile” terminology for characterizing shale gas reservoirs. Thus, it is possible to accurately identify brittle and ductile intervals on well logs and through core studies. Furthermore, employing stratigraphic techniques such as identification of flooding surfaces can aid in defining petrophysical and elastic properties at sequence and parasequence levels. Conversely, petrophysical evaluations can aid in identifying sequence boundaries and flooding surfaces. In this paper, we apply this relationship to characterize potential shale gas reservoirs from South Australia Early Permian Roseneath and Murteree shale formations. Four core samples from two wells were used for minerals quantification, identification of pore density and interconnectivity while log data was used for stratigraphic and geomechanical analysis. Mechanical tests was also conducted using servo-controlled triaxial apparatus to determine compressive strength, elastic properties and Mohr-Coulomb failure. Experimental results suggest that rock strength and elastic parameters vary with maximum Young's modulus of 48.64MPa and 68.82MPa and Poisson's ratio between 0.15–0.29 and 0.06–0.34 for the Roseneath and Murteree shales respectively. Since hydrocarbon migration paths in shale reservoirs tend to be short, productive zones can be restricted to a stratigraphic interval. Thus, the conclusion of this work is significant to better understand shale gas reservoir characterization and identification of stratigraphic intervals susceptible to fracturing. This knowledge can be used to plan well completion strategy and stimulation treatment that has the potential to reduce cost and optimize production.