Frequently Asked Questions

A surface reading of seven pulses, (or even six) should be interpreted as wellbore inclination greater that the maximum reading of the tool.  We advise you at this time to run an alternative survey device (single shot or other) to confirm the Teledrift reading and obtain an accurate wellbore inclination.

The flow rate for surveying is variable based on well conditions and will change as measured depth increases.  When the pumps are started, the flow of fluid acts on the pulse knob at the top of the tool and forces it down past a series of restrictions, creating the pulses that are read at the surface.  Pumping too fast will force the plunger down to quickly and you may not be able to decode all the pulses at the surface.  Pumping too slow will delay the pulse knob passing the restrictions, cause weak pulses, and you may not receive all of your pulses in a timely manner.  Do not adjust the pump rate during the survey as this may create a false signal.

Ask your authorized Teledrift representative for assistance in determining an optimum flow rate to survey.

As the measured depth of the wellbore increases, there is a corresponding lengthening of time to receive all of the pulses from downhole.  Make sure to wait several minutes past what you believe to be the final pulse to confirm that you have received all of the pulses.  Also, make sure that you wait the full three to five minutes when taking a survey; it will take longer for the fluid column to settle and the tool to recognize the no-flow situation.  You may find that you need to close the kelly-cock valve or open the stand-pipe bleed off line to completely relieve pressure from the downhole assembly.

Tapered drill strings act to attenuate the signal from the downhole tool.  Make sure that the surface recorder is set to it’s most sensitive readings before attempting to survey.  The signals that you receive may not have the normal shape of previous signals.

Higher mud weights will act to attenuate the signal from the downhole tool.  Be aware of this in your recognition of signals.  Also, higher mud weights will necessitate a longer period for the mud system to reach equilibrium and the tool to obtain a survey.  Again, make sure that you wait the full three to five minutes after the mud flow has stopped for the tool to obtain a survey.

The pulse signal from the downhole tool can be affected by multiple factors.  OBM versus WBM, mud weight and viscosity, measured depth of the well bore, tapered string features.  These factors can all come into play when stopping to obtain a survey, and again when the flow is restarted to pump that survey information to the surface.  As a general rule of thumb, as all of the above factors increase, increase the time to record a survey and realize that it will take longer for the pulses to be detected and decoded.  Start counting survey store time from the time that the flow has stopped and the pressure gages are reading zero.  Set your recorder to maximum sensitivity and start the recorder when you start your pumps on.  Bring your pumps up quickly, but smoothly. 

The Teledrift tools are designed to operate in harsh drilling conditions.  Realizing this, any steps that the rig operator can employee to minimize interference with the operation of the tools is seen as beneficial to the tool performance.  Teledrift does not supply drill pipe screens, but strongly recommends that a surface drill pipe screen is run with all of their tools.