Novel Workflow for Shale Gas Reservoir Characterization

Shales may contain significant volumes of organic matter and constitutes the key source rock for hydrocarbon reservoirs. Today these types of organic rich shales are being economical exploited in situ and have become recognized as unconventional reservoirs. The current reservoir characterization technology has been evolved over decades focusing on sandstone - and carbonate – rocks. This technology is not directly applicable for shale reservoir characterization. One important difference is that permeability and porosity in shales are order of magnitude different from sandstone - and carbonate – rocks, another that we are describing the source - rock it. We will in this paper propose a new procedure for characterization of shale reservoirs. The workflow is highlighted in figure 1. Input data is typically cores, well-logs and surface seismic data in addition to micro-seismic data .The core, well-logs and seismic data are integrated in a hierarchical fashion that allows characterization of key features in the shales. The total organic content (TOC) in the shales is an example of such a feature. Løseth et. al has in a recent paper that acoustic impedance (AI) in organic-rich claystones decreases nonlinearly with increasing TOC percent. Further claystones mixed with low-density organic matter have significant higher intrinsic anisotropy than otherwise similar non-organic claystones.