Occurrences of deep gas are commonly found in clastic reservoir rocks. The great depths of these reservoir rocks often result in rocks with low porosity and poor permeability. In order for these reservoirs to be productive, natural fracture systems or induced fractures from stimulation processes are required to allow gas to flow to the well bore. In order to assess the potential of these reservoirs, explorationists around the world depend on data acquired from resistivity imaging tools to visualize the fractures.
This paper will discuss fracture analysis using resistivity image data that provides better reservoir characterization on fractured reservoir than the normal open hole logs. Image data has higher resolution compared to the basic open hole data, and allows for fracture visualization down to 2mm. Petrophysical analysis using basic open hole data will average out the fine details of the fracture and its effects on porosity and permeability. Image based petrophysics known as “Image petrophysics” allows for the conversion of high resolution image data to high resolution petrophysical properties which provides greater understanding of the impact of the fractures on reservoir characterization. The use of Image data calibrated with either core data or basic open hole data allows for the derivation of high resolution porosity distribution. Permeability derivation can also be achieved using image data calibrated with core data. This process can also be extrapolated to wells that are un-cored.
This paper will also discuss the challenges of acquiring image data from these deep environments by employing memory based image tools that can be conveyed using a broad range of conveyance techniques.