Previous attempts made to intervene in a gas storage well had been unsuccessful, with a HUD tagged higher than expected. The client wanted to diagnose the problem and identify the cause, which was suspected to be debris related, ultimately returning the well to maximum production.
A camera and PrecisionCollector cleanout tool were mobilized for the operation, to be run in combination with a PowerTrac Tractor to convey the tools in the high deviation section of the well. The camera was to inspect the condition of the wellbore and indicate the nature and position of any debris found. The PrecisionCollector was to both remove any debris hindering well access and choking production, and to collect and recover the debris to surface for further analysis. The PrecisionCollector assembly comprises a rock bit to mill and dislodge the debris, as well as multiple collection chambers to retain and recover debris to surface. Debris milling and collection is done simultaneously. Depending on the volume of debris encountered, multiple runs can be carried out.
Following identification of a debris bridge by the downhole camera at circa 9500ft, the PrecisionCollector was run in hole. The debris bridge was milled successfully, with clear progress seen on surface via real-time tool measurements. As depth progress was made by the PrecisionCollector assembly there were indications of additional smaller debris patches being confronted and removed. The camera was redeployed in the well and captured video footage that clearly showed the debris bridge had been removed. Upon progressing deeper, a second debris bridge was encountered. The PrecisionCollector assembly was run again and successfully cleared this second, deeper debris bridge. Once at bottom, the PrecisionCollector was used to collect a debris sample from the sump of the well, retrieving a total of three litres of varying debris type. The entire operation was carried out by the Altus multi-disciplined e-line and slickline crew with the logging engineer operating both the PowerTrac and downhole video camera. This resulted in significant reduction in POB.