New bit-nozzle program simplified the calculation of hydraulic program and is fitted up with field conveniences. The fundamental principle of this calculation is based on the fact that each pressure loss in the circulation system can be converted to the length of drill pipe which have the equivalent pressure loss.
The effect of oil spotting on differential pressure sticking of drill pipe was studied by simple apparatus. As a result, it was found that a sodium dialkyl sulf osuccinate was the most effective wetting agent, and the wetting agent promoted oil coating (wetting) on the surface of mud's solids and drill tools. Therefore, 1) Oil plus wetting agent reduced the adhesive force between filter cake and drill pipe, 2) As the material displaced the water at this contact, differential pressure approached zero.
Portland cements were cured at temperatures from 80° to 200°C, and the compressive strengths were measured. These laboratory tests showed that at elavated temperatures compressive strengths retrogressed because of "dicalcium silicate alpha-hydrate" formed in the cementing compositions. Elevated temperature retrogressions were eliminated by adding suitable amounts of artificial pozzolan.