Rhourde Attar field in the northwestern Algerian desert is exploited from the Lower Devonian sandstone. This formation is composed of sandy and silty-sandy intervals with thin, shaly intercalations. The reservoir is characterized by very porous sands (20 to 25%), which also show relatively low permeability (1 to 15 md). Deposition of chamosite minerals reduced permeability, without reducing primary porous volume. This paper proposes a pillar fracturing technique designed to overcome formation constraints and enhance production.
Beyond the moderate petrophysical properties related to rock diagenetic history, the reservoir is suffering from a gradual depletion trend, limiting the oil production rate and driving the bottomhole operating condition below the bubble point. It was proposed that placing a highly conductive fracture stimulation treatment could possibly help overcome these constraints. An oil producer well of the field was selected for the first application of a pillar fracturing technique combined with a resin to consolidate the created channels within the fracture.
The pillar fracturing technique allows conductivity maximization through the placement of open channels within the stabilized proppant pillars. This unique fracture geometry is achieved by pulsing clean fracturing fluid stages alternated with slurry stages that carry the propping agent. The proppant pillars are then stabilized with the addition of a specifically designed resin to coat the proppant as it was being pumped throughout the entire fracturing process. Proper candidate selection, accurate fracture modeling, and employment of proven pumping equipment are crucial elements for achieving a successful and safe intervention. The implementation of this stimulation technique provided positive results both in terms of operational execution and final well performance.
Additionally, this technique mitigates the risk of undesired screenout by reducing the proppant volume compared to a conventional job. Moreover, the initial production of the well revealed a significant improvement while the long-term performance showed a stabilized trend. Based on these outcomes, the use of this technique could face a fast increase within the Algerian market, considering also possible refracturing interventions on older wells.