Schlumberger Well Service Company contracted Boller and Chivens to manufacture a predesigned oil sampling test assembly.  The assembly would be lowered down to predetermined elevations in oil wells that were presently being drilled. At a predetermined depth a pair of shoes in the center of the test assembly would expand out to the drilled diameter and seal the area from any local contamination that area. A signal would then be sent down to fire two projectiles to break up the local strata. Well pressure would then push gaseous and/or liquid samples into storage cylinders located at each end of the test assembly. The shoes would then be retracted and the assembly would then be brought back up to the surface for analyzing the retrieved contents.

Over a period of several years, Boller & Chivens manufactured over 50 of these oil-sampling assemblies.

Pictured below is a close-up of the rubber sealing shoe with the projectile ports in the center.