Ritesh Kumar Sharma

Seismic reservoir characterization of Duvernay shale with quantitative interpretation and induced seismicity considerations — A case study

AbstractThe Devonian Duvernay Formation in northwest central Alberta, Canada, has become a hot play in the past few years due to its richness in liquid and gaseous hydrocarbon resources. The oil and gas generation in this shale formation made it the source rock for many oil and gas fields in its vicinity. We attempt to showcase the characterization of Duvernay Formation using 3D multicomponent seismic data and integrating it with the available well log and other relevant data. This has been done by deriving rock-physics parameters (Young’s modulus and Poisson’s ratio) through deterministic simultaneous and joint impedance inversion, with appropriate quantitative interpretation. In particular, we determine the brittleness of the Duvernay interval, which helps us determine the sweet spots therein. The scope of this characterization exercise was extended to explore the induced seismicity observed in the area (i.e., earthquakes of magnitude >3  M) that is perceived to be associated with hydraulic fracture sti...

Identification of sweet spots in shale reservoir formations

The main goal for shale resource characterization is usually the identification of sweet spots which represent the most favourable drilling targets. Such sweet spots can be picked up as those pockets in the target formation that exhibit high total organic carbon (TOC) content as well as high brittleness. At any well location, when the resistivity and sonic transit-time curves are scaled and overlaid, they follow each other almost everywhere, except in the kerogen-rich zones, where they cross over. While such a cross over is only seen visually, it can be transformed into an attribute known as ΔlogR that incorporates both the resistivity and velocity information and is expected to be high for organic-rich zones. Such a transformation would allow us to identify organic-rich zones only at well locations. In this study, we introduce a methodology for computing ΔlogR as a volume from seismic data. For doing this, the ΔlogR curve computed at well locations is correlated with different attribute curves that can be derived from seismic data. An attribute curve which shows the maximum correlation is selected and crossplotted against ΔlogR to determine the relationship between the two. This relationship is then used for extracting the ΔlogR volume from 3D seismic data.

Characterization of shallow high-amplitude seismic anomalies in the Hoop Fault Complex, Barents Sea

The shallow migrating hydrocarbon fluids in the western Barents Sea are usually found to be associated with high seismic amplitudes. We have attempted to characterize such shallow high amplitude anomalies in the Hoop Fault Complex area of the western Barents Sea. The workflow devised for discrimination of anomalies that are associated with the presence of hydrocarbons from those that are not, and quantify them further includes, the computation of a set of seismic attributes and their analyses. These attributes comprise the coherence, spectral decomposition, prestack simultaneous impedance inversion, and extended elastic impedance attributes, followed by their analysis in appropriate crossplot space, as well as with the use of rock physics templates. Finally, we briefly discuss the futuristic efforts being devoted towards the integration of diverse data types such as P-cable seismic as well as CSEM data, so as to come up with an integrated assessment for the prospects and mitigating risk.

Current Workflows for Shale Gas Reservoir Characterization

Summary Optimizing directional drilling performance in U.S. shale plays and around the world continues to focus on increasing the hydraulic efficiency of the drilling system consisting of the drill bit and the directional drilling tool (RSS/Motor). Bit/tool balling is one of the prevalent causes of redu ced system hydraulic efficiency, which leads to bit ROP degradation. This paper details knowledge gained from laboratory tests of drilling under pressure in a drilling simulator. The tests are designed to replicate the balling that occurs in the field and determine whic h variables cause the system to ball-up.

9C Seismic Modelling For VTI Media

An extrapolation method is presented for modelling 3D-9C seismic data in media that are transversely anisotropic. Fourier decomposition is used so that wavefield extrapolation proceeds as a set of distributed, monochromatic extrapolation steps in depth. Three component (3C) geophones are implemented on each grid point of the horizontal reflecting surface. A 3C model source wavefield is extrapolated by 3D phase shift operators in anisotropic media to each grid point. There, a rotation matrix transforms the source polarization into the orientation of the multicomponent geophone. The polarization angle (dip) of the incident compressional wave and the horizontal projection of the associated slowness vector at each grid point are the essential parameters of a rotation matrix. Travel times in anisotropic media are accommodated through plane wave transformation and phase shift, and a propagation angle is produced. For each geophone component, the polarization angle is calculated from the propagation angle. Synthetic examples are given to demonstrate this approach.