Operating conditions and conventional BHA lead to excessive NPT
PetroChina's Tarim basin development plan for the Hade field, located in
the northwest Xinjiang region of China, called for producing 33 million tonUS
of crude oil within a year. In pursuit of this goal, PetroChina planned to
drill 81/2-in ultradeep horizontal wells in sand reservoir formations at depths
of more than 5,000-m TVD. Beyond drilling at great depths, the tight laminated
reservoir being targeted is in a formation with hard and abrasive
characteristics punctuated by hard stringers. The technical limitations of the
rig and downhole equipment made steering very difficult, and drilling the hard,
abrasive formation produced excessive shock and vibration affecting
conventional BHA performance. These operating conditions required that three to
five runs be made to reach a section's TD at ROPs that averaged 2.65 m/h.
RSS and bit combine to answer operational challenges
To directionally drill the Hade field application more efficiently,
Schlumberger recommended an engineered drilling system that included the
PowerDrive Archer high build rate RSS and a Smith Bits 81/2-in Mi519 PDC bit.
The fully rotating PowerDrive Archer RSS provides the necessary control to
maintain directional requirements while punching through hard stringers and is
specially suited for high dogleg severity (DLS) applications.
The 81/2-in PDC bit was selected after a performance analysis was
conducted using the IDEAS integrated drillbit design platform. This included
simulation drilling with several bits based on the BHA design and drilling
parameters consistent with PetroChina's application.