API RP 13B-2:2005 pdf download
API RP 13B-2:2005 pdf download.Recommended Practice for Field Testing of Oil-based Drilling Fluids.
7 Filtration
7.1 Principle
7.1.1 Measurement of the filtration behaviour and the filter cake characteristics of an oil-based drilling fluid are fundamental to the treatment and control of a drilling fluid, as are the characteristics of the filtrate, such as the oil, water or emulsion content.
7.1.2 Filtration characteristics of an oil-based drilling fluid are affected by the quantity, type and size of solid particles and emulsified water in the drilling fluid, and by properties of the liquid phase. Interactions of these various components can be influenced by temperature and pressure.
7.1.3 Filtration tests are performed at ambient (low) temperature and at high-temperature conditions to provide data for comparison purposes. Two filtration procedures are given: one for testing up to 175 °C (350 °F) and one for testing from 175 °C (350 °F) to 230 °C (450 °F). Use only the filtration equipment and procedure specified for the temperature required.
NOTE No low-temperature filtration test procedure for oil-based drilling fluids is specified herein, but it can be performed much like the water-based drilling fluid test provided in ISO 10414-1.
7.1.4 Either the 175 cm3, 250 cm3, or 500 cm3 unit can be used for testing filtration up to and including 175 °C
(350 °F). For testing above 175 °C (350 °F), only the 500 cm3 unit shall be used. It shall be equipped with a
thermocouple to measure the temperature of drilling fluid in the cell, and it shall use a porous filter media.
7.2 High temperature/high pressure test up to 175 °C (350 °F)
7.2.1 Apparatus
a) High-temperature/high-pressure filter press, consisting of:
1) filter cell, to contain working pressures up to 9 000 kPa (1 300 psi) at temperature;
2) pressurized gas source, such as carbon dioxide or nitrogen, with regulators; NOTE Nitrogen is preferred.
3) heating system, to heat to 175 °C (350 °F);
4) high-pressure filtrate collection vessel, maintained at proper back-pressure (see Table 2) to avoid flashing or evaporation of the filtrate;
5) filter cell, containing a thermometer well, fitted with a removable end, a filter-media support and with oil- resistant seals.
NOTE Valve stems on each end of the cell can be opened or closed during the test.
CAUTION Not all manufacturers’ equipment is capable of achieving the same temperatures and pressures. Rigid adherence to manufacturer’s recommendations as to sample volumes, temperatures and pressures is essential. Failure to do so could result in serious injury.
Do not use nitrous oxide cartridges as pressure sources for HT/HP filtration. Under temperature and pressure, nitrous oxide can detonate in the presence of grease, oil or carbonaceous materials. Nitrous oxide cartridges shall be used only for Garrett gas train carbonate analysis (see annex I).
7.2.2.6 Keeping the two valve stems closed, adjust the pressure on the upper pressure regulator to 690 kPa (100 psi) higher than the minimum back-pressure value, as shown in Table 2. Set the lower regulator to the minimum back-pressure value, as shown in Table 2, for the test temperature. Maintain this pressure until the test temperature is reached.
NOTE If the time required to reach test temperature exceeds 1 h, the heater may be defective and the validity of the test is questionable.
7.2.2.7 When the sample reaches the selected test temperature, open the lower valve stem and immediately increase the pressure on the upper regulator to 3 450 kPa (500 psi) higher than the back-pressure. This will start the filtration process. Start the timer. Maintain the test temperature to within ± 3 °C (± 5 °F) during the test. If the back-pressure rises above the selected back-pressure during the test, cautiously draw off and collect a portion of the filtrate to reduce the back-pressure.
7.2.2.8 Collect the filtrate in the long, slender graduated cylinder (or optional graduated cylinder). Read the volume of the 30-mm total (water plus oil) filtrate. Also read volumes of solid and aqueous phases, if present.
NOTE The long, slender glass cylinder allows more accurate detection and measurements of volumes of oil, water and solids in the filtrate. Heating of the cylinder near an emulsion interface can improve separation of water, solids and oil in the filtrate.
7.2.2.9 Immediately after collecting the 30-mm filtrate, close the upper and lower valve stems to contain the pressure. Following the manufacturer’s detailed instructions, bleed pressure off the regulators and hoses, then disconnect the pressurization system. Remove the cell from the heating jacket and allow cell to cool to below 50 °C (125 °F). Keep the cell upright during cooling, depressurization and disassembly.
CAUTION Pressure in the filter cell can be dangerously high, even after the cell is cooled. Opening cell before pressure is released can result in injury.
7.2.2.10 Bleed pressure from the filter cell by slowly opening the upper valve stem. Avoid spraying drilling fluid as gas exits the stem. Ensure that pressure is fully released before dislodging the cap. Carefully disassemble the cell.
7.2.2.11 Pour the liquid from the cell.
