Extended-reach drilling (ERD) enables reservoir access with lower overall well construction costs and significant reduction of surface infrastructure costs and footprint. For example, drilling an extremely long horizontal well from a location on land can reduce costs by eliminating the much higher expense of building offshore platforms and managing subsequent logistics.
However, in long horizontal wells that produce from multiple reservoirs with different properties, uneven drawdown can hinder production and promote early gas or water breakthrough. In addition, high friction in the long horizontal causes a heel-to-toe pressure loss effect that exacerbates reservoir pressure differences.
For a new extended-reach well, an operator needed a strategy to optimize production from six zones in four reservoirs with dissimilar permeabilities and pressures. Earlier in the project, the operator had used conventional extended-reach completions composed of screens and passive inflow control devices (ICDs). Although the ICDs and nozzles were engineered for the expected reservoir conditions, uncertainty in estimated reservoir properties resulted in the wells experiencing early gas breakthrough. Because they did not have a monitoring system to provide better understanding of flow potential, the wells required multiple interventions to enable managing the production uncertainty.
For the new well, the operator wanted to address the uncertainties with active flow control and measurements to better characterize zone potential and drain oil without gas breakthrough. This would only be possible with a completion that could be installed to TD, deliver zonal measurements, and enable control from surface in real time. Consequently, six Manara electric ICVs equipped with sensors for measuring water holdup, fluid flow rate, pressure, and temperature at the formation face were installed in the well.
When the well began flowing, engineers fully opened the ICVs for all six zones. Measurements of oil production showed significant contributions from Zones 5 and 6, less from Zones 1 and 2, and no flow from Zones 3 and 4. Reservoir analysis indicated that Zones 3 and 4 should be significant producers, so the operator concluded that the permeability was damaged by drilling mud. With a conventional completion, cleaning the tight zones would have been impossible.
However, using the Manara ICVs in the well, the engineering team was able to choke Zones 5 and 6 to increase drawdown in the damaged zones. The pressure change induced flow that cleaned up the permeability damage without further intervention. After the zones stabilized, the engineers reopened all the ICVs and measured overall production, with contributions from all zones including the two previously damaged ones.
To maximize well production, the engineers then used SLB production optimization digital workflows for intelligent completions to calculate the optimal setting for each ICV. The result was a production increase of 25% compared with the production when all valves were fully open—including 40% from the two damaged zones that would not have produced at all without the real-time drawdown control.
Using the electric completion system for the cleanup and optimization process saved the operator approximately 2 days compared with using slower hydraulically actuated valves.
