The benefit of borehole gravity in horizontal monitoring wells for time-lapse applications

†† ‡ ‡ Summary In this paper, we present a study on the added benefit of jointly inverting surface and borehole gravity data for reservoir monitoring. In particular, we show that timelapse measurements in horizontal monitoring wells can provide significant additional information about fluid movement over surface data alone. The primary advantage of such monitoring wells lies in the option to preferentially orient them with the geometry of a production or sequestration field. Additionally, well heights can be chosen to maximize the signal strength in consideration of instrument accuracy, while balancing data sensitivity to the lateral extent of the reservoir to be monitored. We demonstrate this study using a realistic representation of a difficult CO2 EOR site and the joint interpretation of surface and borehole data with highly constrained inversion.