BAKER HUGHES - Drilling Fluids Reference Manual

TABLE OF CONTENTS
graphically too. The downhole mud density and the rheological parameters are available as
diagrams.
The figure below is a typical ADVANTAGE SM output for a deepwater well. Note the tabular data on
the left side of the Figure 13 - 12 or the graph in Figure 13 - 12 labeled “Downhole Density”
indicates the ESD at the bottom of the wellbore is 12.73 ppg and the surface mud weight is only 12.5
ppg. This is due to the pressure and temperature effects on compressibility and expandability on
SBM’s and OBM’s.
Figure 13 - 12
Deepwater Well Example
HOLE CLEANING AND BARITE SAG
INTRODUCTION
Removing cuttings from the wellbore is the most important function of the drilling fluid. Whether the
wellbore is being drilled on land, the offshore continental shelf, or in deepwater, the drill bit cannot
advance if the cuttings are not removed. In deepwater wells the implications of not cleaning the
wellbore are: spikes in ECD, numerous short trips, back reaming, poor cement jobs, stuck drill pipe,
stuck casing/liner, etc. The bottom line results usually mean increased well costs to the operator and
an unhappy client of the mud company.
Barite sag is defined as the variation in mud weight seen at the flow line. This is usually observed
after extended periods without circulation. At times barite sag will result in similar problems to those
seen with inadequate hole cleaning.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 13-24