ANSI API RP 10B-6 pdf free download

ANSI API RP 10B-6 pdf free download.Petroleum and natural gas industries一Cements and materials for well cementing一 Part 6: Methods for determining the static gel strength of cement formulations.
6 Test method using rotating-type static gel strength apparatus
6.1 Apparatus
The apparatus contains a pressure chamber that can be heated and pressurized according to a simulated cement job schedule. The SGS is calculated from the torque required to rotate a paddle of known geometry at very low speed. The rotation speed of the paddle during the SGS measurement portion of the test is normally a continuous 0,000 009 2 r/s (0,2°/mm). The initial stirring to simulate placement in the well is typically conducted at
2,5 r/s ± 0,25 r/s (150 r/min ± 15 r/min). The rotating-type static gel strength apparatus shall be calibrated according to the manufacturer’s instructions. During the test period, the temperature and pressure of the slurry in the test cell is increased in accordance with the appropriate well-simulation test schedule (see 6.2.2). Determine the temperature of the cement slurry by use of an ASTM E220 classification “special” type J thermocouple located in the centre of the testing cell. The temperature-measuring system shall be calibrated to an accuracy of ± 2 °C (±4 °F). Calibration shall be performed no less frequently than every three months.
NOTE Changing the rotational speed of the apparatus can be required depending on slurry design. The permissible range of rotational speed for the apparatus is 0,000 006 9 r/s (0,15°/mm) to 0,000 023 1 r/s (0,5°/mm).
6.2 Test procedure
6.2.1 If there is a batch mixing time being used for the job, the test schedule should include this segment. The slurry should be exposed to the anticipated temperature conditions during the batch mixing time. The pressure at this time shall be atmospheric. The stirring is typically maintained at 2,5 r/s ± 0,25 r/s (150 r/min ± 5 r/min). If there is no batch mixing time, omit this step.
6.2.2 Calculate the expected time to bottom and the expected placement time required to displace the cement to the flow zone. Ramp the cement slurry to bottom-hole circulating temperature (TPBHC) and the bottom-hole pressure (P1w) in the expected time to bottom. Then ramp to the circulating temperature and pressure at the flow zone. The time interval to ramp to the circulating temperature and pressure at the flow zone is the expected placement time to the flow zone, minus the expected time to bottom. After the circulating temperature at the flow zone is reached, hold at the specified temperature and pressure for 5 mm ± 30 s to allow for temperature stabilization. Maintain paddle rotation at 2,5 r/s ± 0,25 r/s (150 r/min ± 15 r/min). In cases when an extended period of fluidity is expected, the test temperature may be increased to static temperature at the flow zone in 240 mm after reaching the circulating temperature at the flow zone plus 5 mm for temperature stabilization. During the placement simulation, the temperature and pressure shall be maintained within 3 °C (5 °F) and 2 MPa (300 psi) of the appropriate elapsed time versus temperature and pressure targets. Within 10 mm after the end of the ramp, the temperature and pressure shall be within ± I °C (±2 °F) and 0,7 MPa (100 psi) of the specified values.
NOTE During the time of stirring at API/ISO rotational speeds [2,5 r/s ± 0,25 r/s (150 r/min ± 15 r/min)], the test gives an indication of slurry consistency. It is not an exact slurry thickening time consistency since the paddle does not conform to the required dimensions for determining thickening time.
6.2.3 For the SGS determination, at the end of the slurry placement simulation, the rotational speed is changed from the typical 2,5 r/s ± 0,25 r/s (150 r/min ± 15 r/min) to 0,000 009 2 r/s (0,2°/mm) or other permissible rotational speed. Maintain circulating temperature and pressure at the zone of interest. During SGS determination the temperature and pressure shall be maintained within ± I °C (± 2 °F) and ± 0,7 MPa (± 100 psi) of the target values.
6.2.4 Record the initial SGS and the elapsed time when the sample is placed in SGS determination mode from the previous placement simulation. Record the time to 50 Pa (100 Ibf/100 ft2), 100 Pa (200 lbf/100 ft2), 150 Pa (300 Ibf/100 ft2), 200 Pa (400 Ibf/100 ft2) and 250 Pa (500 Ibf/100 ft2) SGS and, CSGS. Where applicable, determine the critical static gel strength period (CSGSP) by measuring the time required for the cement to progress from the critical static gel strength (CSGS) value (see Annex A) to a SGS of 250 Pa (500 lbf/100 ft2). The manufacturer, model and rotational speed of the apparatus used to make the SGS determination shall be reported.
ANSI API RP 10B-6  pdf download.