Increase of geological prospecting works and target well depth requires improvement of drilling technology as well as scientific and technical level for well construction upgrading. One of the significant trends in longhole construction upgrading is application of effective drilling mid and makeup technology allowing to prevent operating problems and drilling costs minimization.

The following main problems with any of the operating fluid are expected in course of longhole construction:

  • poor condition of clay argillaceous rock. In spite of that considerable advances have been made, problem of the rock poor condition still exists and subject to be solved.

  • low thermal stability of drilling mud. Depending on geotechnical conditions low thermal stability of drilling mud may result in major complications up to well abandonment. Thermostable water base mud rated for 160 °C and above and up to 130-140 °C in aggressive salt scenario is practically non-existent.

  • problems with scaling and development of abnormally pressured zones.

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