METHOD OF ASSEMBLY OF A STRING OF ELEMENTS FOR DEEPWATER DRILLING AND ULTRADEEP, OBSTRUCTION ELEMENT AND CORRESPONDING USE OF THE SAME IN THE SAID DRILLING STRING

摘要

Method of assembly of a string (S) of drilling elements for deepwater drilling. Each drilling element comprises an axial through hole (21), through which drilling mud (M) can at least flow, and two connection portions (23) for connecting it in series in said string. The method comprising the following steps: a) assembling a lower portion of the string (15); b) taking a first drilling element (2); c) assembling said at least one first drilling element (2) with other drilling devices in order to create a first section (Tl) of the string ( S ); d) repeating steps b)-c) until said lower portion (15) arrives in the proximity of the blowout preventer (4) or in the proximity of the bottom (G); e) beginning the assembly of second drilling elements (20) while executing a drilling cycle, for the purpose of creating at least a second section (T2) of the string (S); f) repeating step e) until the second section (T2) has reached an extension equal to a desired drilling depth. After step a) and before step b), at least one step s) is carried out, wherein at least one third drilling element (3) is assembled, which comprises at least one obstruction element (5) for preventing a backflow (B) from being generated in said string (S).