Professor PANG Zhonghe and his team collect water samples from 25 wells and drill cores of sections of the Guantao formation in the Bohai Bay Basin (BBB) for measurements of mineralogy, water chemistry and isotopes.

A hydrogeological and geochemical characterization has been carried out on the Neogene Guantao formation in the BBB, North China, focusing on the Beitang sag in Tianjin area. It is a sedimentary basin filled with continental sediments that is rather different from previous studies but typical for Chinese sedimentary basins. A good combination of reservoir (sand aquifers with high porosity and permeability) and cap-rock features (multi clay layers with great thickness and low permeability) is confirmed. Water chemistry with low salinity, elevated porosity and permeability of the host formation, low to medium temperature, and pressure ranges offers favorable conditions for CO₂ sequestration. The isotopic composition of Guantao formation water suggests the presence of carbonate in the host rock so strong water–rock interaction within the reservoir is expected which may result in changes of formation porosity and permeability after CO₂ injection.

Fig. 1. Location of the study area and distribution of sampled wells from the Beitang sag in the Bohai Bay Basin (Ng: Guantao formation, Nm: Minghuazheng formation). (Image by PANG)

Fig. 2. Plot of δ13C vs. 14C age of geothermal water from the Guantao and Minghuazheng aquifers, Beitang sag, Bohai Bay Basin, North China. (Image by PANG)

Fig. 3. Hydrogen and oxygen isotope ratios in Neogene formation waters from the Beitang sag. (Image by PANG)

Fig. 4. Chemical compositional changes. (Image by PANG)

Pang et al. Geochemistry of a continental saline aquifer for CO₂ sequestration: The Guantao formation in the Bohai Bay Basin, North China. Applied Geochemistry. 2012, 27:1821–1828 (Download Here)