This article describes the specifications and inspection requirements of the various BHA components for horizontal wells.

Inspections requirements

• All BHA components should have received a full inspection prior to use on an extended reach well.
• Stress relief grooves are required on all components (including non magnetic components and jars).
• The complete BHA should be returned for further inspection after completion of the well.

Drilling Jars

• Enhanced hydraulic up/down short jars should be used.
• Two sets of jars can be run; one set above the drill collars and a second set in the cased hole section.

Drill Pipe Requirements

• Drilling horizontal sections places high buckling and torque stresses on the drill pipe, and the use of torque and drag analysis is essential to predict actual loads.
• Typically, G 105 drill pipe is sufficient between the jars.
• S-135 drill pipe is typically required from the upper jar to surface.
• Actual requirements and design loads shall be indicated in the Drilling Programme.
• HWDP should have smooth hardfacing only to reduce casing wear..

BHA Design

• The Directional Contractor shall use offset well and contractor experience to design BHA.
• The Drilling Supervisor and Directional Drilling Engineer shall base their BHA configurations on those proposed. However, modifications based on the previous BHA runs will be required.
• The use of steerable systems which have a neutral tendency in rotary mode are optimum for these hole sections.