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Sound Velocity Of Drilling Mud Saturated With Reservoir Gas
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 6th International Congress of the Brazilian Geophysical Society, Aug 1999, cp-215-00279
Abstract
Drillings muds are used to balance subsurface pressures, lubricate the drillstring, clean the<br>bottom of the hole, remove cuttings and aid formation evaluation. During drilling, the mud<br>is pumped down the drill pipe and returns via the annulus between the drill string and the<br>formations. If the pore-fluid formation pressure exceeds that of the mud column, reservoir gas<br>can enter the wellbore? creating a kick and causing severe damage. Knowledge of the in-situ<br>sound velocity of drilhng mud can be useful for evaluating the presence and amount of gas<br>invasion in the drilling fluid. Technologies such as mud pulse acoustic telemetry require this<br>information. In the following sections, we propose a model for calculating the in-situ density<br>and sound velocity of water-based and oil-based drilling muds containing formation gas.