Effect of gas field production and CO2 injection on brine flow and salt precipitation
conference paper
This paper reports modeling of gas field produc-tion and CO2 injection from a theoretical reser-voir based on characteristics of the P18 gas field in the Dutch offshore, which consists of four geological deposits with different petrophysical properties. We especially focus on the brine flow during and after exploitation of the reservoir, which affects salt precipitation and dissolution in the near-well area. We first computed the water saturation (Sw) with depth, in static equilibrium with a free water level (FWL) at the bottom of the reservoir. We then computed production of the gas field, predicting a very low brine production and mobility, without salt precipitation. Subsequently, injec-tion of dry CO2 leads to dry-out and salt precip-itation in the near well zone and a maximum permeability reduction of 24%. After abandonment, brine flows towards the well, resulting in redissolution of precipitated salt, leading to salt saturated brine in the near-well bore area. After 1,000 years, it is predicted that supersaturated brine is concentrated in the lower part of the reservoir, where solid salt still remains. The computed long-term effects of brine mobility could influence predictions of well-cement degradation and well-abandonment strategies like intentional clogging.
TNO Identifier
467014
Source title
Proceedings Tough Sympsosium 2012, Lawrence Berkeley National Laboratory, Berkeley, California, September 17-19, 2012
Pages
1-8
Files
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