Enhance completion efficiency and production in brownfield

Samarang oil field offshore East Malaysia had entered a production decline phase, and a new approach was needed to improve reservoir productivity. With limited reserves still in place, PETRONAS was seeking cost-effective completion techniques to revitalize the field, which consists of several stacked reservoirs, some partially depleted and some with a strong water drive from aquifers. Traditionally, dual-string completions with multiple stacked cased hole gravel packs had been installed to maximize the number of layers produced from each well. These designs lacked independent zonal flow control and thus could not optimize commingled production and water cut, limiting oil recovery. Integrating gravel packs with an intelligent completion was needed.

PETRONAS worked with Schlumberger to find a solution for increasing hydrocarbon recovery by targeting previously unattractive marginal reserves and commingling them to bundle the production into economically attractive opportunities. Completion installation efficiency was crucial for controlling costs. In the workover well selected as a candidate, oil production had declined below economic levels and water cuts for the various producing layers had reached 90% to 100%. The Samarang asset management team decided to abandon the watered-out layers and perforate four shallower oil-bearing zones.

Deploy multizonal sand control and modular intelligent completion

AllFRAC screens use shunt tubes and nozzles to ensure a complete pack. The screens were deployed in tandem with MZ shunt-tube multizone packers, which are sealed inside the casing to provide isolation between the closely spaced reservoir zones. Stacking conventional gravel-pack packer assemblies, which are longer, would have restricted the perforation intervals to much shorter lengths and negatively impacted production. During the single pumping operation, the top two zones (treated as a single interval) were packed conventionally while the middle and lower zones were packed via the shunt tubes extending through the packers. ClearPAC polymer-free viscoelastic surfactant gravel-pack fluid was used to prevent formation damage and ensure packing of perforation tunnels.