Abstract
This paper explores a successful method for predicting high-resolution saturation, permeability, and porosity from resistivity imaging acquired with wireline logging. By integrating the best attributes of resistivity imaging and both wireline NMR and pressure testing information, this method is shown to produce better reservoir evaluation and production enhancement when applied to a homogenous sandstone reservoir that is relatively free from micro-bound porosity and layering.
Three available wireline formation evaluation technologies used in concert with conventional macro-wireline logs can substantially improve reservoir evaluation in terms of porosity, permeability and saturation. These technologies include the following:
Nuclear magnetic resonance (NMR), includes tools such as the MRIL®-Prime tool, which provides accurate estimates of formation porosity, permeability, saturation, and hydrocarbon properties, albeit with relatively coarse vertical resolution compared to resistivity images, which can be enhanced by post-processing techniques.
Resistivity imaging, such as the X-tended Range Micro Imager (XRMI™) tool with vertical resolution down to 0.10 in. These tools provide high-resolution porosity, permeability, and saturation prediction in clastic reservoirs based on estimates of micro-bound and producible porosity by means of integration with NMR and conventional logs.
Pressure and sampling tools, such as the Reservoir Description Tool (RDT™) formation tester, which provides reservoir pressure, anisotropy, lateral and vertical connectivity, producibility, and fluid mobility measurements, which can be converted to permeability using fluid viscosity from fluid sampling.
The new method uses a special post-processing technique for enhancing the vertical resolution of the NMR data. By providing reliable and accurate predictions of saturation, permeability, and permeability, the method integrates NMR-bounded porosity, conventional resistivity, and the NMR saturation resulting from the magnetic resonance imaging analysis (MRIAN™) post-processing model.
