Abstract
Identifying the sand-prone zones and the severity of sanding in wells with multi-layered hydrocarbon producing reservoirs or commingled completions is the key to designing fit-for-purpose sand control measures to ensure the continuation of safe operations, enhancing productivity and recovery. Sanding evaluations are commonly calibrated against either surface sand observations, hole fill events, hold up points or rock mechanical simulations. Although advanced geomechanical and petrophysical analyses can identify the likely sand producing intervals, in the absence of direct and independent downhole observations, the validity of such analyses can often be a concern. This study shows results of the emerging technology of Distributed Acoustic Sensors (DAS) from fiber optic surveys in live wells used for downhole sand detection in a mature offshore gas field in SE Asia. The integration of DAS signal processing with production logging (PLT), surface sand detectors and independent geomechanical and petrophysical evaluations proved very useful for through tubing sand control decisions in the study wells. The results of the petrophysical and geomechanical sanding evaluation provided in-depth insights into the likely sand-prone zone under varying flow rates and given reservoir pressures. Sand-prone zones are identified for current conditions and the severity of sanding with further depletion or flow rates is assessed for individual wells. DAS signal interpretation results in the second trial well are in full agreement with PLT data, surface sand monitors and the independent geomechanical evaluations. In the first well, further fine-tuning of DAS signal processing or a re-run may still be needed. Geomechanical analyses indicate that in both study wells, sand face failure will be very likely, even at the lowest tested flow rates of less than 15 MMSCFPD where no or limited sands were detected at the surface. DAS signals also indicate sand ingress signals at low flow rates in both wells. The workflow developed appears applicable to different well trajectories, depletion, and drawdown conditions. The technology has the potential for advanced production management that optimizes production and improves sand management decisions in existing wells with sanding issues.
