CALCULATING THE DILUTION QUANTITY

The dilution required to compensate for the incorporation of 37.9 bbl of drilled solids was the 759 bbl of new mud, less the volume of the drilled solids in the new drilling fluid built, or 721 bbl. This is 19 bbl of dilution per bbl of incorporated solids (721.0 bbl / 37.9 bbl). The calculation for the dilution, that is, the volume of new mud that must be prepared, is

V=( 100 – % ) %

where V = the volume of new mud (dilution) required, in bbl / bbl of incorporated solids, and % = the concentration of drilled solids.

The volume of new mud plus the incorporated cuttings, which is the total volume increase, is simply the volume increase factor (VIF) multiplied by the volume of incorporated solids:

VIF = 100 / %

At 5%vol drilled solids, V, the dilution volume, is 19 times the volume of incorporated solids, and the volume increase is 20 times that.

Sedimentation tray with auger

APPENDIX: AMERICAN PETROLEUM INSTITUTE METHOD

Using the current API technique for the problem: The dilution corresponding to total incorporation of the drilled solids (no separation) would be the volume of solids drilled divided by the drilled-solids raction; in this case:

97.3 bbl / 0.05, or 1946 bbl .

The dilution factor (DF) is the ratio of the volume of new mud actually prepared to that which would have been required with no drilled-solids removal. In this instance, a volume of 759 bbl of new mud has been built
and the DF is 759 bbl / 1946 bbl, or 0.39. The required dilution was
39% of what it would have been if none of the drilled solids had been
separated.

Drilled Solids Removal Factor

Observe the relationship between DF and the drilled-solids removal
of 61% calculated above. The drilled solids removal factor (DSRF) is defined as :

DSRF = 100 ( 1 – DF )

It is numerically equal to the SREE previously calculated. In this case:

DSRF = 100 ( 1 - 0.39 )  = 61%.

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