Operations Manual
TFA The TFA of the drill bit is critical for the operation of the D-Tech RST system. The tool operates with a specific pressure drop across the BHA. If this pressure drop is not achieved, then the RST system will be underpowered and will produce unpredictable and erratic steering results. All of D-Tech's runs to date have been with PDC technology bits. Rock bits have shown to work well with push-the-bit rotary steerable systems and we see no issue running with a tri-cone style rock bit.
Steps to ensure proper TFA.
1. Select the correct bit for the application, identify the nozzles and fixed ports. 2. Determine the mud weight that you will be drilling with (careful consideration needs to be taken if the mud weight is expected to increase greatly throughout the section). 3. Determine the flow rate required during the run. 4. Use the D-Tech TFA Calculator software to calculate the TFA and the usable flow range for the run. Each RST tool size has an optimal required pressure drop, see table below, staying in the upper range will produce increased steering force. In order to achieve the recommended pressure drop, the tool requires a smaller TFA than typical directional drilling without an RST system. Taking time to understand the application and limitations of the drilling rigs hydraulic delivery system are crucial in setting a correct TFA for the operation.
Tool Size
Pressure Drop Required
RST 475/500 RST 675/650 RST 800/900
520 to 640 psi 500 to 620 psi 430 to 520 psi
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