Operations Manual
TFA Calculator For the D-Tech Rotary Steerable to generate the required piston force, a bit pressure drop is needed. This is achieved by adjusting the Bit TFA. There is a difference in pressure from the inside of the RST piston to the outside of the pad/piston in the annulus and, depending on which RST size you are utilizing, the required pressure drop will vary. Using the TFA Calculator – Figure 2 The simple to use D-Tech TFA Calculator software is used to calculate the correct bit TFA for the run and provides the RST usable flow range for the run. Hydraulic data can be easily recalculated to suit any operational scenario that may arise throughout the run. 1. Select the hole size in inches – This automatically populates the correct RST tool size as well as the target pressure drop. 2. Complete the operations panel – If a range in flow rate or mud weight is expected to be used during the job, input the highest likely values. 3. Input the number of nozzles in the bit, and click on the Find TFA button. 4. The recommended TFA will be shown, to get as close to but not exceed the target pressure drop. 5. The usable flow range is shown in the right panel, with a graph showing the expected pressure drop throughout the range. The usable flow range is calculated with a pressure drop tolerance of 20% - Be aware that steering performance may be affected as the pressure drop decreases.
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