10 Tips for Assembling an MWD Tool String

10 Tips for Assembling
an MWD Tool String

By Grant Caskey, Product Support Specialist
October 6, 2014

We all know that assembling an MWD tool string can be an exercise in frustration, especially if you don’t have a suitably flat surface for your stands (see tip #1). Whether you are new or experienced, the following 10 tips should help you conquer this task in no time (so that you can move on to the stuff you enjoy).


  1. Check in with company man when you arrive on rig site—he might have a good location in mind for assembling the tool string. Also, ensure that there is a minimum of traffic in the area.
  2. Locate an open flat area so that all of your modules can line-up with a minimum of adjustment.
  3. Use two stands per module to avoid see-sawing modules.
  4. Lay out all of the modules on stands in the order in which they will be connected. This is an obvious one, but the last thing that you want to do is mess-up the order.
  5. If centralizers are not attached to the downhole end of your tools, attach them first before attempting the tool string assembly.
  6. Shoot for a straight line to make assembly easy. It may help to stand back and do a visual check.
  7. Apply plenty of lubricant to the centralizer threads before engaging the threads—you can never have enough of this stuff. We recommend Dow Corning™ 111 valve lubricant.
  8. Find the sweet spot for threading the two ends by adjusting the uphole end of the connecting module—sometimes it just takes a minor adjustment to the angle or elevation for the two ends to thread easily.
  9. Don’t forget that spanner wrenches can be adjusted for ease of use. Shorten the tooth to help with disengaging the wrench from the module. If you are having trouble keeping the wrench on when turning, adjust the tooth out.
  10. Don’t stomp on your wrench! When tightening your connections, be wary of the amount of torque you apply: aim for 350 ft./lbs. of torque. More pressure may cause damage; less pressure may result in the connection loosening. As a rule of thumb, a 2 ft. wrench multiplies your weight by 2, e.g., a 200 lb. person will put 400 lbs./ft. of torque on the connection.


Related Articles:

Tips & Tricks: High-Siding, Orienting, and Seating your MWD

SureMate Connector White Paper

Tool String Assembly Comparison White Paper

It’s all in the Plumbing: Rig Pumps, Manifolds and Standpipe

Like what you’ve read?

Subscribe to our company newsletter, The Pulse, to get articles like this sent right to your inbox every month. Just click here to sign up.