9.6 ERD and Horizontal Transit

With the prevalence of ERD and Horizontal Well Profiles, gyro surveying became even more difficult to perform by conventional wireline operations. Various techniques were adopted with improvements made relative to technology advances in both assisted tool transport and survey tool development.

Side-Entry Sub:– The Side-Entry Sub was first used with the Magnetic W/L Steering Tool Systems (Pre MWD) in order that drilling could proceed during deeper drilling operations without the requirement to trip out the W/L – Steering Tool from the drill pipe to make a connection (Add Pipe). Using this system enabled W/L Gyro Surveys to be performed in extended reach horizontal wells, with the survey tool latched within the BHA and surveys recorded at each planned depth interval.

The Side Entry Sub consisted of a sub with a side wall orifice with associated clamp and stuffing gland arrangement which allowed the cable to pass through the sub wall with the clamp and gland seal applied as required. The BHA/drill pipe would be tripped in hole to the high angle survey start depth. The W/L and survey tool would then be run to bottom within the pipe entering via the side wall sub connected to the drill pipe at surface. The survey would then commence by tripping in hole to TD with pipe added as normal. The assembly was then tripped out (with outrun data also recorded) to retrieve the Sub at surface with the W/L Tool then pulled out of hole. The system was subsequently applied to W/L FE logging prior to equivalent MWD sensor development.