Abstract:

The complexity and incidents often happen while drilling the conventional oil and gas wells can fully meet at the sidetrack wells. However, due to characteristics of the sidetrack wells with more complex trajectory and smaller diameter, the complexity and incidents facing in drilling the sidetrack wells have specific nature. In this paper we deeply analyze the causes of complexity and incidents when drilling sidetrack well with unconventional diameter such that cones dropped, string broken or quickly worn out, wells being seriously instable... On that basis, analyzing the working status of string. Results showed that, the complexity and the incidents often encountered in drilling unconventional diameter sidetrack well had specific nature; the string worked in extreme hardly conditions with the complex stress state. The paper has also proposed guidelines for choosing the string and suggests a scientific perspective for the issues remaining to research, evaluate, calculate and improve the entire process and technology - technics sidetrack drilling with unconventional diameter