A Simple Yet Impactful Innovation to Optimize Production of Low-Quality Reservoir (LQR) by Using a Modified Venturi Choke, Pilot Case at Matured Waterflood Field Bravo, Central Sumatera Basin

Abstract

In a mature asset like Bravo field in Central Sumatera Basin, the ‘easy to produce’ oil is becoming increasingly rare and hard to find. Therefore, pursuing oil at the low-quality reservoir (LQR) has become one of the main focuses nowadays. Despite having huge potential due to its low recovery nature, optimizing LQR production comes with set of challenges. This paper highlights a successful innovation to unlock the LQR potential, offering a solution to maximize production. The innovation involves the application of a modified venturi choke (VC). Basic principle of this method is producing the LQR zone (low rate, low watercut) with the assist from a better-reservoir quality zone below, namely High-Quality Reservoir (HQR) zone (high rate, high watercut). Unlike the conventional commingle approaches, the modified VC is strategically placed between the zones, applying fluid restriction to the HQR zone. Acting as a downhole choke, it induces a substantial pressure drop, resulting in a jetting effect that efficiently strips out fluids from the LQR zone, thereby enabling optimal oil production contribution. Pilot execution on the first 2 wells in Bravo Field successfully delivered 100 BOPD incremental oil gain, proven that this newly developed method is working very well. The installation of the venturi choke (VC) has led to a substantial improvement in oil contribution from the LQR zone, a fact confirmed through oil finger printing analysis. Notably, the LQR zone, which was theoretically unable to produce even with the smallest pump and would not contribute significantly through conventional commingle methods, has demonstrated its production potential using this approach. The established flow process and screening criteria are also proven effective to capture potential candidates that cannot be produced with traditional commingle methods. Comprehensive analysis of historical production data, swab tests, G&G interpretation, reservoir simulation, and well modeling played a pivotal role in selecting the most suitable LQR candidate for this optimization. Additionally, considering VC material is available at relatively large quantities on hand, makes it feasible to implement the same approach in numerous other LQR potentials within the field and the surrounding region. This scalability further highlights the benefit of this method in unlocking LQR potential beyond the initial pilot wells.