Challenge: Identify flowing zones and establish communication from a subsea well’s lower completion to its upper completion without impeding production flow

Solution: Installed WellWatcher Flux(TM) multizonal reservoir monitoring system on the sand screen exteriors along the sandface, along with reservoir interpretation and real-time communication software in the operator’s office

Results:

• Established wireless communication from lower completion to upper completion

• Provided permeability information for modifications to lower completions and transmitted real-time cleanup data

Subsea market presents challenges

The subsea market is growing rapidly, but because of the expense of subsea well intervention, fewer production logs are acquired. Reservoir information is therefore insufficient for an accurate understanding of reservoir connectivity, drainage, and flow assurance.

An additional constraint for wells requiring sand control is that sandface sensors must be deployed on separate completion runs.

With the high cost of subsea well intervention curtailing the acquisition of production logs, the industry needed a new permanent monitoring system that included

• a robust mechanism to deploy sensors
• a method for communicating real-time sandface data from the lower to the upper completion
• a multidiscipline interpretation strategy to maximize the value of those sensors.

Permanent monitoring system requires no modification to subsea tree

To address these needs and constraints, SLB developed the WellWatcher Flux multizonal reservoir monitoring system to provide a unique wireless communication solution that can easily integrate with other companies' hardware and requires no modification to the subsea tree. Instead of individual gauges on mandrels, the digital sensors have been miniaturized and distributed along a single spooled bridle. A large-bore inductive coupler provides wireless power and data communication between upper and lower completions, and a reservoir simulation package models the temperature response of different gas inflow scenarios. Moreover, the WellWatcher Flux system is designed for permanent installation to provide data over the life of the reservoir.

After a comprehensive 2-year engineering development program, the WellWatcher Flux system was deployed in a Southeast Asian high-flow-rate deepwater gas well in water up to 1,200 m [3,937 ft] deep. An inductive coupling was used to power the miniaturized digital sensors clamped to the exterior screens along the sandface and to transmit the data in real time to the subsea wellhead. The system then transmitted the data to the operator's office onshore.

This system deployment was the first of six such systems required for this major subsea field. The WellWatcher Flux system will be used for monitoring temperature to establish flow allocation profiles along each wellbore, determining reservoir depletion, connectivity, and channel connectivity, and helping the operator plan subsequent infill drilling to optimize reservoir drainage across the field.

Permanent inductive coupler ensured sandface data transmission

When the first system was turned on, the operator received data that resulted in modifications to the lower completion prior to cleanup.

The sandface data were transmitted to shore in real time during the cleanup and were used to continuously monitor the reservoir when production began.

The initial deployment of the WellWatcher Flux system showed that the system's permanent inductive coupler can withstand debris and vibration. It also provided the breakthrough needed for the industry to take subsea permanent monitoring to the next level of sensing technology.