The Valhall Field is one of the most significant and well-known oil fields in the Norwegian Continental Shelf (NCS). Characterized by its chalk reservoir, Valhall Field is challenging to exploit due to its high porosity and low permeability. Over decades of production, the reservoir has become significantly depleted, leading to substantial pressure drops and lower oil production. Unpredictable reservoir pressure makes it difficult to maintain stable drawdown and increases the risk of chalk or proppant influx—complicating production and intervention operations.
In conventional well cleanout operations, relying on a single data source can exacerbate risks for CT cleanouts in underbalanced conditions. In NCS wells, solids settling or the forming of beds in the wellbore can cause the CT string to stick, especially in conditions where fluid loss to the reservoir reduces the annular velocity needed to lift solids to the surface. To optimize well cleanout and restore oil production in two wells (Well A and Well B), the operator required real-time measurements of oil, water, gas, and solids returns at the surface.
SLB deployed the dual-energy Vx Spectra™ surface multiphase flowmeter and the ACTive™ powered downhole measurements system, a component of the ACTive real-time downhole coiled tubing services. This pairing enabled the operator to adjust pumping rates, optimize fluid composition, and deliver continuous power throughout the underbalanced well cleanout campaign. Accurate real-time flow rate measurements helped the operator monitor returns and leverage natural flow for solids removal—optimizing material usage, reducing rig time, and mitigating operational risks in both wells.
Well A results:
Well B results:
This well intervention marked the world’s first underbalanced CT cleanout workflow to combine the capabilities of the Vx Spectra surface multiphase flowmeter with the ACTive powered downhole measurements system, successfully setting a new benchmark for CT cleanouts in the NCS.
