The Sleipner CCS facility has been the first offshore storage operation at industrial scale and the longest operated in the world since 1994. For many years, Sleipner CO2 injection site has been monitored by three dimensional seismic surveys. Several studies utilize full waveform inversion to estimate the CO2 properties in this area directly from seismic data. The common challenge on these FWI studies is the offset limitation in the available streamer data. Therefore, FWI is very challenging in this scenario. Additionally, muti-parameter reconstruction of CO2 plume properties is not yet discussed. In our case study, we apply a reflection oriented workflow, which utilizes both diving and reflected waves through Joint Full Waveform Inversion (JFWI). It helps up to compensate the offset limitation of the data by utilizing the transmitted energy between the reflectors and the receivers to constrain the low wavenumber component of the velocity along the reflection wavepath. This naturally brings us to consider the monitoring problem in a multi-parameter sense as JFWI, in the acoustic approximation, works with a parameterization separating the P-impedance and the P-wave velocity. We thus obtain both structural and quantitative properties based on impedance and velocity models in a single workflow.