High-Resolution Topographic and Chemical Surface Imaging of Chalk for Oil Recovery Improvement Applications

Chalk is a very fine-grained carbonate and can accommodate high porosity which key characteristic for high-quality hydrocarbon reservoirs. A standard procedure within Improved Oil Recovery (IOR) seawater-injection repressurizes the reservoir pore pressure. Long-term will influence mineralogical processes as dissolution precipitation of secondary minerals. These minerals (<1 micrometer) precipitate during flooding experiments mimicking conditions. Due to their small sizes, analysis from traditional scanning electron microscopy combined with energy dispersive X-ray spectroscopy not conclusive because insufficient spatial resolution detection limit. Therefore, chalk was analyzed high-resolution imaging by helium ion (HIM) mass spectrometry (SIMS) first time. Our aim identify mineral phases at sub-micrometer scale locations brine–rock interactions. In addition, we wanted test if current understanding these alteration be improved combination complementary techniques give new insights IOR. The HIM-SIMS revealed well-defined crystal boundaries provided images excellent lateral resolution, allowing identification specific phases. Using this methodology, developed chemical clay could define exact location on micron-sized coccolith grains. This shows that it essential study nanometer in general, specifically research field applied petroleum geology