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The directional trajectory control operation of Well YD103H was implemented by Cavaville for CNPC. The well was completed on January, creating the record of the shortest directional cycle, the fastest directional ROP and the highest mud density in the directional well section of the same well type in the block.
Well YD103H is located in Block Yudong 1 in Xinhe County, Xinjiang Uygur Autonomous Region. There are many sets of pressure system and gypsum-salt rock of unstable thickness longitudinally in the block, with complicated formation and pressure system. Overflow and stuck drilling occurred repeatedly during the drilling of the high-pressure brine layer and gypsum-salt section in the adjacent well. This section is also characterized with long open hole section, poor BHA deflecting capability, large friction and torque, as well as difficult trajectory control.
The most challenging part lay in the directional drilling of the gypsum mudstone and salt bed section. Cavaville adopted customized salt-resistant motor. Moreover, the trajectory of this section was optimized in advance to reserve enough compound drilling section, reduce sliding drilling of gypsum mudstone formation, and reduce the static time of BHA in the open hole section. In this way, the risk of stuck drilling was minimized. The gypsum mudstone and salt bed section was successfully drilled through by two trips.
Directional section: 4685-5356m, 5224-5730m; footage: 1177m; designed period of directional drilling: 106 days; planned operation period: 92.9 days; actual period of directional drilling: 55.72 days, 50.28 days earlier than the designed period and 37.18 days earlier than the planned operation period. During the 8 trips of directional drilling, the tools ran smoothly and reliably without any failure. It creates the record of the shortest directional drilling period and zero accident.