STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

688 Drilling and Well Completions
where VbW is the water requirement for the added barite (gal/lb).
Therefore, the initial volume is
v, =
I
1+8.33(0.01) -14.0
700135.0( 1 +35.0(0.01)
35.0( 1 + 35.0(0.01)
Thus
= 612.99 bbl
700 - 612.99 = 87.01 bbl
is the volume of initial mud that should be discarded before adding barite. The
weight of barite needed is
w, = 35'0 (87.01)(42)
1 + 35.0(0.01)
= 94,744 lb
The total volume of water to be added with the barite, Vw (gal), often called
dilution water, is
Vw = vbw W,
(4-48)
= 0.01 (94744)
= 947.4 gal
Determlnation of OIlMlater Ratio from Retort Data
To determine the O/W ratio, it is first necessary to measure oil and water
percent by volume in the mud by retort analysis. From the data obtained the
oil/water ratio is calculated as follows:
% oil by vol
% oil in the liquid phase = x 100
% oil by vol + % water by vol
% water by vol
% water in the liquid phase = x 100
% water of vol+ % oil by vol
The oil/water ratio or O/W = % oil in liquid phase/% water in liquid phase.
For example, retort analysis:
51% oil by vol
17% water by vol
32% solids by vol