Optimize multizone production in marginal offshore oil field

An operator planned two wells in a marginal field offshore east Malaysia. The field consisted of multiple dipping, heterogeneous, unconsolidated sandstone reservoirs. The stacked reservoirs had a large gas cap with only marginal oil in place. Achieving maximum reservoir contact in this type of formation required horizontal wells.

Install a modular intelligent well completion to manage reservoir zones

After studying various well completion designs—including horizontal wells with passive versus active zonal control—Schlumberger recommended an intelligent completion using modular downhole equipment. This well completion would maximize reservoir drainage points and minimize overdepletion of the high-permeability less-productive zones, thereby enhancing reservoir performance and improving project economics.

The intelligent well completion enables the operator to monitor the flow from individual zones and adjust zonal contributions. This flow control function prevents or minimizes water and gas encroachment, and in this case, it would also help control both the aggressive gas cap expansion at the heel of the well and, as the field depleted, the aquifer’s coning up from the dipping well toe.

The modular, compact intelligent completion equipment reduces installation time and potential for service quality incidents by removing tasks from the rig’s operational critical path to offsite or deck preparation.

Upfront engineering analysis ensures that the flow control valve sizes and positions are tailored to the range of reservoir and production characteristics for the target well. The final completion assembly integrates multiple components, including flow control valves, zonal isolation packers, permanent pressure and temperature sensors, and a mechanism that provides absolute feedback of valve choke position.

Produced more than 99% oil and saved USD 400,000 per well

Because the well completion components can be prepared off the rig’s critical path, zero NPT was incurred before and during installation. Rig time for installation was reduced to just 33% of the time required by conventional passive intelligent completions—8 hours per zone instead of the typical 24 hours per zone. The time saved was approximately 32 hours for each well, an equivalent of USD 400,000 per well. Seven months after the intelligent completions were installed, the two wells were producing more than 99% oil with a water cut of less than 1%.