Logging in Open Hole, Brazil

March 2008

The Well Tractor configured for open hole and tandem operation performed a successful micro–imaging logging job in the Polvo field offshore Brazil. The well was horizontal with a maximum deviation of 99° at 3,901 ft MD. 

The micro-imaging tool was run in hole on wireline to about 3,564 ft MD at 72°. Both Well Tractors were then powered up in tandem and tractored down to 3,975 ft MD. The solution included 20 ft of spacers between the tractors, which would allow at least 1 Well Tractor® to maintain its pushing force under a scenario of up to 42 ft of washouts. Prior to the job, a well simulation determined that the entire tool string could be conveyed on 1 Well Tractor® alone even with the second tractor in the string.

The prejob planning considered two critical down hole areas in this job: the initial rathole, going from casing into OH and approximately 330 ft of soft marl discovered during drilling, just days before the job. To avoid the logging equipment sinking into the initial rathole, a bullnose was applied and due to the tandem setup, the rathole was not noticed during operation. The bottom hole assembly would not pass the soft marl and it was concluded that a “wash & ream” carried out after the caliper log most likely had worsened conditions increasing the washout in the marl.

The priority of the logging job was within the tractored area and a high quality log was performed due to e-line conditions. The customer decided to utilize the same setup for several upcoming OH logs.

 

Well Data

Total depth:                14,180 ft
Maximum deviation:    98.78º
Maximum dogleg:        8.2º/3,350 ft
Temperature:             162°F
Tractoring time:          2:46 Hr