DETERMINATION OF TOTAL BACTERIA COUNT AND SELECTION OF INJECTION WATER QUALITY RATING CHART FOR WATER FLOOD NEEDS IN SUMATRA OIL FIELDS

Abstract

An important factor affecting the success of a water flood project for secondary recovery
is the quality of the water being injected. In this research, the water quality tests were
focused on determination of total bacteria counts of the analyzed injection water sample
using ASTM D 5465-93 and selections of injection water quality rating chart for water
flood needs in Sumatra oil fields. The results of microbiological laboratory tests of all
analyzed injection water samples showed three parts. An injection water sample of N - 82
containing type of bacteria Bacillus sp with the total bacteria counts 5.02 x 100 colonies/cc
was categorized as no. 1 water quality rating chart. Subsequently, G – GS injection water
sample indicated Bacillus sp with total bacteria counts 4.28 x 101 colonies/cc and Bacillus
Laterosporous with total bacteria count 3.31 x 101 colonies/cc for G – 90 water sample.
Two samples mentioned above were classified as no. 2 water quality rating chart. Next,
Bacillus Alvei was found in T – 21 injection water sample with total bacteria count 1.85 x
102 colonies/cc and Bacillus Pathothenticus in T – GS injection water samples with total
bacteria count 2.61 x 102 colonies/cc. Position of water quality rating chart for both last
samples were no. 3. These results gave valuable and useful information before implementation
of water flood in the oilfield.