Open hole gravel packing of reservoir sections drilled with oil based fluid is traditionally performed with an aqueous carrier fluid. This typically involves displacing oil based fluid to aqueous fluid once the gravel pack screen is in place. In reservoirs with swelling or unstable shale this approach reduces the risk associated with open hole exposure to aqueous fluid over time. However experience has shown that instability can still occur resulting in an incomplete, or even an aborted gravel pack. In addition, mixing of incompatible oil and water based fluids downhole has the potential to generate very viscous emulsions that negatively impact gravel pack efficiency and well productivity. The objective of the new technology was to maintain borehole stability, eliminate fluid incompatibility and enable a complete gravel pack.An oil based carrier fluid has been developed and qualified using laboratory and yard scale testing. The fluid is a solids free invert emulsion that exhibits near Newtonian rheological behavior; thereby promoting settling of proppant during gravel packing. The density of the fluid is controlled by adjusting the volume fraction and density of the brine phase. The fluid has been qualified up to a density of 1.25 SG with further potential to achieve a density of 1.63 SG.The oil based carrier fluid has been introduced on a mature field, with a long history of gravel pack completions. Progressive reservoir depletion has created operational challenges, resulting in inconsistent gravel pack performance. Consequently, several procedural changes have been implemented over time. Reservoir inclination is typically up to 50°, open hole length up to 200 meters, and bottom hole static temperature around 90°C. Gravel packs were most recently performed with a 1.10 SG aqueous carrier fluid.The new carrier fluid has exhibited stable properties during implementation on multiple well completions. Gravel pack efficiencies have been consistently good, at 100% or higher. As a result, well productivity expectations have consistently been achieved or exceeded. The operational time for installing the lower completion compares well with the traditional approach with aqueous fluid.The implementation of oil based gravel packs in multiple wells, allows a comparison with brine based gravel packs in the same field. It is therefore considered to be an industry first.

Achieving flow performance in openhole sand control completions often requires removal of the annular gap between the screen section and wellbore. For the first time in the industry, patented hydraulic screen technology has been used to provide wellbore support and overcome the challenges associated with gravel packing in depleted reservoirs with low operational margins. This paper demonstrates how new technology has been adopted by an operator in Norway to provide effective downhole sand control in an offshore environment faced with continuous reservoir pressure depletion. Detailed job planning and evaluation of risks when adopting new technology is described.The case study describes a producer well drilled to 2580 m, at a maximum deviation of 30º, and temperature approximately 90ºC. With the sand control equipment run to depth closed ended, the liner hanger and hydraulic screens are set by surface applied pressure. When set, the screens extend radially to close the annular gap and provide wellbore support; production ports in each screen provide the flow path from the reservoir to production tubing. The liner hanger packer was set and reservoir isolation barrier valve closed in the same trip providing testable barriers, prior to displacing the well for upper completion operations.The paper outlines how adopting new technology challenges openhole gravel packing and delivers effective downhole sand control in a depleted reservoir. The operator has demonstrated savings associated to operational planning, logistics, HSE risks and rig time. Production rates meet expectations with all screens contributing to flow.