The First Saudi Arabian Trilateral Oil Well in Unconsolidated Sandstone Reservoir

Abstract

AbstractMultilateral wells to achieve Maximum Reservoir Contact (MRC) have been widely implemented in a number of new carbonate fields' development in Saudi Arabia, resulting in substantial financial improvement of these assets. The successes achieved with this well architecture justified extending its use into a sandstone oil field that has been characterized with heterogeneous and poorly consolidated sandstone formation. This paper chronicles the multi-disciplinary approach and processes employed to evaluate, plan, and execute the first trilateral well in an unconsolidated heterogeneous sandstone reservoir in Saudi Arabia. The objectives of the ML well are to maximize reservoir contact to enhance sweep efficiency and improve well productivity and to promote the ML application in this complex field to extend field's production plateau. Initial well construction involved side-tracking an idle vertical well that has been shut in due to high WC and low productivity. Prior to drilling the laterals, a deviated pilot hole was drilled across the entire reservoir which helped optimize placement of the laterals. Reentry of an existing well to successfully steer and drill three long horizontal open drain holes into the reservoir imposed several constraints and added to the list of challenges.Incorporating sand control in a multi-lateral environment poses a number of challenges, with complexity driven by the Technology Advancement Multilateral (TAML) level demanded for the junctions between the motherbore and laterals, and by overall well functionality required. Well completion involved installation of an expandable sand screen (ESS) completion in the mainbore and Premium Sand Screens (PSS) completions in the two laterals to facilitate sand-free commingled production from all three laterals. The PSS completions featured a wash-down capability in the high-build angle laterals and also incorporated swell packers positioned just inside the laterals to ensure sand-tight conditions at the TAML Level 3 junctions. Following installation of upper ESP completion, a post-rig extensive clean-up program was conducted to unload all three laterals. The well is currently producing sand-free oil at three times the rate of neighboring single-lateral wells. Following the success and capturing the lesson learned from this trial, another ML well will be drilled in the field.