First Simultaneous Application of Rotary Steerable/Ream-While-Drill on Ursa Horizontal Well

摘要

The development wells at the Ursa tension leg platform (TLP) site use 8.625" production casing in conjunction with 5.5" tubing to achieve the highest daily production rates to date in the Gulf of Mexico. The desire for large diameter production casing and the small margin between mud weight and fracture gradient at the deepwater Ursa site combine to require drilling a larger sized hole than the drift diameter of the previous casing string for all of the casing intervals. Bi-center bits have successfully drilled all of the intervals in one run except the section to total depth (TD). The last, 1,000' true vertical depth (TVD) on the first two wells were drilled and then under reamed prior to running casing. The directional plan for the third well at the Ursa TLP included an 86 deg turn in azimuth and building hole angle to horizontal by 18,300' TVD. The previous lack of success drilling the TD interval in one trip with bi-center bits led to using a 9.5" bit below a 6.75" AutoTrak rotary steerable closed loop system (RCLS) in combination ith an 11.4" ream-while-drill (RWD) sub. This bottom hole assembly (BHA) would simultaneosuly drill and ream the hole to the proper diameter, thus eliminating the separate under-reamer run. Druign the initial pilot hole penetration of the target reservoir and two subsequent sidetracks to build to horizontal, the RCLS/RWD system drilled approximately 20,000' of Miocene age sand and shale sediments at inclinations that ranged from 30 deg to 88 deg. The instantaneous and average rate of penetration (ROP) increased 30