Sand Containment in Deep Gas Fields

In the central area of the Sultanate of Oman, gas and condensate from five different fields are processed through one gas production station which has been in operation for over 10 years. Despite the highly consolidated nature of these deep sandstone reservoirs, sand was observed in the inlet separators. This work will: Illustrate the methods used to identify the source of sand (field, well, and formation).Establish short, medium, and long term solutions. A strategy was created to investigate the source of sand and the extent of damage inflicted on the facility. Mitigation measures in the form of short to long term solutions were also implemented, addressing issues arising both in the surface and subsurface. Monitoring included clamp-on sand detectors and Sonic MPLT with camera with mitigation work including modification of the inlet separator and desander installation upstream the inlet separator Two fields were identified to be the potential source of sand, based on the clamp on sand detection campaign. One field has commingled production from three reservoirs and was later confirmed to be the true source of sand; the second field was identified to be producing frac proppant only. Different techniques were used to narrow down the sand producing reservoir by comparative study of the minerology of existing core and produced sand samples, sonic MPLT with camera, modeling of formation stress mechanics, and other means of WRM interventions. Results concluded that sand production was not limited to a single reservoir yet the deepest is the major contributer. To maintain the integrity of the facility, both surface and subsurface mitigation measures were assesed. Due to limitations in the existing well completions, surface solutions were preferred.. By evaluating the facility, it was decided to modify the design of the inlet separator to trap the sand and clean it out periodically. In addition, well flow rates were constrained to below the erosion critical velocity to avoid any loss of containment. Finally, an integrity test was conducted to the flowline and equipment (from wellhead to export line), to create a surveillance and maintenance strategy to prevent facility damage. In summary: Modern technologies including Sonic MPLT with Camera proved capable of identifying the formation responsible for sand production under the conditions of fluid clarity and flow condition (Turbulent.Deep, well consolidated sandstone reservoirs are capable of sand production due to depletion and or water production.The facility downstream was protected by means of a simple modification to the inlet separator, demonstrating a simple and unconventional solution.Sand management system usage enabled sand removal from the inlet separator water stream during production, preventing loss of production.