Zhiming Fang

Laboratory measurement and modelling of coal permeability with different gases adsorption

Adsorption of gas on coal will induce coal matrix swelling. Under reservoir conditions these strain changes affect the coal permeability. A series of laboratory measurements of gas permeability of a coal sample from Qinshui basin has been conducted, using a new apparatus developed for measuring coal permeability with various gases adsorption, by use of the transient pulse decay technique. Results show that permeability measured using CH4, N2 and CO2 all decrease with increasing gas pressure under the constant effective stress condition. The permeability decrease shows some variations with gas species. Permeability measured by CO2, CH4 and N2 decrease almost 91%, 70% and 32% respectively, from gas pressure of 0.5 MPa to 4 MPa. The experimental results are then modelled using the Robertson and Christiansen permeability model. Results show the agreement between the modelled results and the experimental results in the pressure range of the experiments, especially for CH4 and N2.

A multilevel U-tube sampler for subsurface environmental monitoring

Sampling fluid in boreholes is always challenging from the standpoints of maintaining integrity and minimizing contamination. This paper focused on the U-tube sampling technology. Firstly, according to initial development motivation, briefly comparison was conducted with available fluid sampling technologies based on driving forces and sample quality. Then, the development history of the U-tube sampling technology was introduced, as well as a comprehensive investigation of its site applications around the world. In particular, a novel multilevel U-tube sampler was designed in China specifically for shallow subsurface, and it had been proven both technically reliable and economically feasible in several carbon capture, utilization, and storage (CCS/CCUS) projects, including the Shengli CO2-enhanced oil recovery (CO2-EOR) project, the Shenhua CCS demonstration project, and the Jilin CO2-EOR project. Finally, the benefits, drawbacks, and future developments of U-tube sampling technology were pointed out as a conclusion. The U-tube sampler used in shallow subsurface is quite suitable in dedicated monitoring projects which specifically require three-dimensional tracing and accurate fluid analysis in a long term.