Monitoring Production From Gravel-Packed Sand-Screen Completions on BP’s Azeri Field Wells Using Permanently Installed Distributed Temperature Sensors

摘要

BP is developing its Azeri field using deviated gravel-packed sand-screen completions producing from the multilayered Pereriv B, C, and D reservoirs. Restricted wellhead access, high rates, and differential depletion of the different reservoir intervals limit conventional production logging possibilities, so BP has chosen to install permanent fiber-optic distributed temperature monitoring systems with its sand screens and to use these systems to monitor production rates and changes over time. The optic fiber has been installed on the periphery of the sand-screen shroud, effectively installing it in the gravel-packed annulus. When the gravel pack is completed, the fiber responds to the reservoir temperature plus the effect of Joule-Thomson warming of the flowing oil caused by the pressure drop (drawdown) in the near-wellbore region. Thermal mixing of the oil with flow from below only occurs once the flow has passed through the sand-screen wire-wrap. Thus a direct measure of each individual reservoir drawdown is obtained from the difference between the fiber-measured temperature and the geothermal temperature in the flowing reservoir intervals. Given the reservoir drawdown, the flow rate can then be calculated.