Page 192 - Petroleum and Gas Field Processing

reported that the processing of 25,000 bb1/day of crude oil could result in
an amount of HCl equal to 65 lb/day [4].

6.2 RELATIONSHIP AMONG VOLUME OF REMNANT
WATER, ITS SALINITY AND SALT CONTENT

Taking one-tenth of 1% by volume of water to remain in the crude as a
basis for our calculation, the relationship between the salt content of the
remnant water expressed in pounds of salt per thousand barrels of oil
(PTB) and its concentration or salinity expressed in ppm is presented
graphically in Figure 1. For other volumes, simple multiples of the
numbers given by this graph are used. The following example illustrates
the use of this relationship.

Example 1
Find the PTB of a crude oil having 10% by volume remnant water if its

concentration is estimated to be 40,000 ppm at 25 C.
Solution
The example is solved using two approaches: One is based on Figure 1 and
the other approach utilizes basic calculations.
1. Using Figure 1, the PTB of crude oil having 0.1% remnant water
with 40,000 ppm salinity is found to be 14 PTB. For crude oil
containing 10% remnant water, the value of PTB obtained from
the figure should be multiplied by 100; therefore, the given crude
contains 1400 PTB.
2. Take a basis of 1000 bbl of wet oil; the B.S.&W. ¼ 10%, and the
saline water concentration ¼ 40,000 ppm ¼ 4%. Then,

Quantity of water in oil ¼ð1000Þ0:1
3
¼ð100 bblÞð5:6ft=bblÞ¼ 560 ft 3
Now, the density of the saline water is estimated using Table 3.
3

For 4% concentration and at 25 C, the density is 1.0253 g/cm ,or
3
63.3787 lb/ft . Hence,
3 3
Mass of water ¼ð560 ft Þ63:3787 lb=ft
¼ 35,828 lb

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.