Page 35 - Geochemistry of Oil Field Waters

24 ANALYSIS OF OILFIELD WATERS

TABLE 3.111
Units in which water analyses may be reported
milligrams per liter = mg/l 1 grain per U.S. gallon = 17.12 mg/l

part per million = ppm 1 grain per Imperial gallon = 14.3 mg/l
milligrams per liter 1 ppm = 0.012 milligram atom per liter
ppm = specific gravity of the water

To convert compounds expressed as parts per million to ions expressed,as parts per
million (where compound is A, Bm):
,(atomic weight A)
ppm ion A = ppm compound A,
Bm molecular weight A, B,
,(atomic weight B)
ppm ion B = ppm compound A,
Bm molecular weight A, B,
To convert parts per million to equivalents per million (epm):
Example: sample contains 28.3 ppm Ca” , what is the concentration of calcium in epm?
Solution; atomic weight Ca = 40.08; valence = 2; equivalent weight =
40.08 = 20.04; then:
2
28 3
28.3 ppm Ca+’ = - = 1.41 epm Ca+’
20.04
Titrim e tric analysis

milliequivalent weight 106
(ml x N of standard solution) x
of determined ion
ml of sample used = mg/l of determined ion
Gravimetric analysis

(grams of preninitnta\ Y ,. atomic weight of determined element 106
molecular
..._. - weig
.,.F.’U”’,
,ht of precipitate
_.-
...
ml of sample used = me/l determined
~
element
%O = parts per thousand or g/kg
Chlorinity (CZ) = mass in grams of silver required to precipitate the halogens in
328.5233 g of sea water
Salinity (S) = total amount of solid material, in grams contained in 1 kg of
sea water when all of the bromide and iodide have been replaced
by the equivalent amount of chloride, when all of the carbonate
is converted to oxide and when all the organic matter is completely
oxidized
%o S = 1.805 x %o Cl + 0.03