Logistical complexities in challenging sandstone formations

An operator drilling in a sandstone formation in a field offshore Equatorial Guinea, an area known for its logistical challenges, used a platform for operations that had limited space and crane limitations.

A majority of the candidate wells were extended-reach with debris in the well, small plug setting windows, low bottomhole pressures, and high H₂S production. In an effort to understand the field, the operator sought to perform production logging and CT interventions to reduce water and gas production and recover oil production. The logistical and space limitations of the extended-reach wells required technology with less operational complexity.

Real-time downhole data during production logging

The operator chose ACTive PS service in its first worldwide integrated production logging service with flow scanner imaging. This integrated package eliminated the requirements for wireline units on location, thus resolving the deck space issues. The ACTive TC live CT tension and compression tool was selected to provide real-time load measurements during hydraulic plug setting. Continuous monitoring of the well provided bottomhole pressure and temperature in combination with casing collar locator depth correlation to optimize the process. The X-11 modular offshore CT unit was used to run the CT, which provided real-time data acquisition and maximum versatility for the operations while maintaining a limited footprint on the platform.

The downhole data allowed for early detection of potential lock up or hang up of tools, enabling early recognition of the potential issues to make accurate, real-time decisions. The operations required a single piece of equipment to fit on the small platform and eliminated the need to swap the unit during the operation.

Integrated system saved 10 days of operations

The integrated system saved the operator one dummy run for each plug setting well and a total of 10 days in rig operations with a total of 16 runs performed in 7 wells within 2 months. The use of the X-11 system and CT in wells with debris saved logistics and lead time, an important savings in Equatorial Guinea. The operator gained a new understanding of the offshore field, which had a great impact on their drilling campaign in 2014. Furthermore, the operator changed the target drilling locations and reduced geologic risk based on the project outcome.

The wellbore cleanout was successful and the well was free of sand to TD after the cleaning operation. Successful production logging was performed in the wells which were available to reach TD. Stimulation operations were proven possible with proper design and execution. In addition, all water and gas shutoff plugs were set successfully and H₂S and water production was reduced.