DIELECTRIC MEASUREMENTS ON ARTIFICIAL COMPACTED CLAY-QUARTZ MIXTURES

摘要

Determination of the hydrocarbon content from resistivity measurements can become challenging if the formation water resistivity is unknown or if the water is fresh. Moreover,in fresh-water shaly sands the formation resistivity is significantly influenced by the clay content.An alternative method,based on the dielectric contrast between formation water and other rock constituents,is provided by dielectric measurements. The multitude of factors influencing dielectric response includes porosity,lithology, texture,brine salinity,and clay type and content.Understanding of the physical mechanisms controlling dielectric dispersion in shaly sands requires laboratory studies in which key petrophysical parameters can be varied systematically from sample to sample.It can be difficult or impossible to obtain such a collection from oilfield reservoirs.The ability to prepare artificial compacted samples with prescribed properties allows systematic variation of the sample lithology,clay content,and brine salinity and also eliminates many of the uncertainties in the sample characterization associated with reservoir cores. A new laboratory setup was constructed for the compaction and saturation of clayquartz mixtures in a dielectric measurement cell that eliminates the need for sample transfer between the compaction and measurement cells.An extensive study was undertaken over a wide range of saturated artificial clay-quartz samples to investigate the dielectric properties of shaly sands.Dielectric spectroscopy experiments were performed on these samples in the range of 10 MHz to 1 GHz at various saturating brine salinities.This paper describes the experimental setup and protocols for compaction and saturation of clay-quartz mixtures and presents measurement results.