1. API Exploration & Production Standards Winter Meeting Fort Worth, January 26 th, 2011 Testing Heavy Brines API 13 J – ISO DIS 13503-3 Hydrometers & Density measurements Bernard Fraboulet, TOTAL Technology Specialists

2. Density & specific gravity measurements  Hydrometers  Density hydrometer Concept : mass per unit of volume (ρ) SI Graduations in g/ml - kg/m 3 USC Graduations in ppg Reference temperatures – SI 20°C – USC : 70°C ( 21.1°C)  Relative density (specific gravity) hydrometer Concept : ratio of ρ sample by ρ water at the same temperature Graduation dimensionless Reference temperature 15.56°C /60°F Ratio of sample density to water density at 60°F : 999,012 kg/m 3 ≡ 0, 999 012 g/ml (8,337 ppg)

3. Hydrometer and normative references  ISO 387: 1977 Principles of construction and adjustment  ISO 649:1981 Density hydrometer for general purposes part 1 : Specifications Part 2 : Test methods and use  for both part : no adoption by USA  ISO 650 :1977 Relative density 60/60°F hydrometers for general purposes  Not adoption by France and Germany and then by CEN

4. Reference & Reporting temperature  ISO 387 Reference temperature Clause 4.1 - density hydrometer : − 20 °C (68°F) − In special circumstances : substitution to 15°C (59°F) or 27°C (80.6°F) −27°C i.e 80°F recommended −other reference temperatures ? USA : 70 °F ? Clause 4.2 : relative density hydrometer − 60°F ( 15,56°C) for liquid and water  Density reporting temperature For any measurement done at a temperature which is not the reference one, a correction is required.  General reporting : when density hydrometer is used why to report at a different temperature than the reference ’s one ?  Does it need to get a direct conversion between SI ref. temperature to USC’s (20°C – 68°F) or between USC ref. temperature to SI’s (70°F – 21°C) ? Reporting temperature proposal : SI report : 20°C USC report : 70°F Left to users

5. Clause 6.2.1 Hydrometer description More accurate description As per ISO’s : class M100 hydrometer 6.2.1.1 Density hydrometer 6.2.2.1 Relative density hydrometer Calibration : at least quarterly

6. Temperature Correction factor Density hydrometer Only a correction linked to hydrometer volumetric change is required : − Standard glass thermal volume expansion 20 x 10 -6 − Table linked to readings and temperature − Minor difference lower than uncertainty if the same table is used for 20°C or 70°F as reference temperature − Two tables ( SI and USC) possible

7. Temperature Correction factor Relative density hydrometer Reference temperature 60°F Correction whatever the reporting temperature Correction linked to −Glass volumetric change −Water temperature density variation  Correction factor : − Complex equation − tables of coefficient − variations as per author/references

8. Proposed changes Clause 6.4.1 Temperature correction for hydrometer – 6.4.1.1 Density hydrometer Correction factor (unit kg/m 3 or 10 -3 g/ml) – 6.4.1.2 Relative density hydrometer sub clause 6.4.1 – no changes – Add SI equations