Abstract
A key component of an unconventional reservoir development is 3D characterization. A necessary precursor for any seismic inversion work is an inversion feasibility study. We shall demonstrate a best practice inversion feasibility workflow that has several key components: regional geology, petrophysics, rock physics, and geophysical analysis. The study shows an integrated approach using spatially diverse well data to cover the entire Delaware Basin, focusing on Avalon and Bone Springs formations. The results show the ranking of petrophysical properties that contributes to the changes in elastic properties. A good relationship was established between TOC, vclay and porosity to elastic logs using both conventional and unconventional RPMs. A class-IV AVO response was observed in the Avalon formation. Finally, our analysis showed that a depth trend based 1D Bayesian classification using bandlimited log data was able to separate organic rich high TOC facies from siltstones and carbonates. To conclude, an integrated approach involving geology, petrophysics, rock physics and inversion feasibility study increased our understanding of the basin and set path for further analysis. The results from inversion feasibility can be used to understand what facies and how much resolution can be resolved from an inversion which is further used to guide the drilling direction and landing zones. The workflow outlined in this study potentially can lead to a 3D inversion analysis, reservoir property estimations from seismic, TOC mapping and finally for finding sweet spots and better drilling/landing zones in the subsurface.
Unconventional oil and gas production have increased dramatically in the last decade, and in the U.S., the Permian Basin is the most prolific of all the basins. The Delaware Basin located in the western part of the Permian Basin has become one of the most active drilling sites with multi-stacked plays (Mire et al. 2017). Most of the production comes from the Permian-aged Avalon, Bone Springs and Wolfcamp formations. These formations are comprised of a heterogeneous mixture of organic rich mudrocks, siltstones and carbonates (Nester et al., 2014). Due to the complex nature of these rocks, it is advantageous to understand and extract useful information from available data resources from all disciplines. Hence, a collaboration to perform an integrated approach between different disciplines is crucial to effectively find solution for complicated technical challenges in the Delaware Basin (Hoang et al., 2019; Anantharamu and Del Moro, 2019).
The knowledge of geology and petrophysical analysis enhances our understanding of the basin and its mineral constituents. A proper rock physics analysis is extremely important for establishing a link between elastic properties and reservoir parameters, which can later be extrapolated to 3D domain using seismic and inversion workflows.