Sand Fill Clean-Out on Wireline Enables Access to Additional Perforation Zones in Gas Well Producer

Abstract

Abstract An Australian operator wanted to explore options for wireline conveyed sand bailing in one of their offshore platform gas producing wells. The objective was to remove twenty-six meters of sand fill inside 9.625" production casing, with an internal diameter of 8.681". Due to the landing nipple at the end of the tubing, the minimum run-in-hole restriction of the production tubing string was 3.987". To limit the number of clean out runs, the latest technology in e-line deployed suction tools with a 4.25" OD was chosen, which provided increased recovery volume over its smaller cousins, plus real-time surface control and monitoring. Because of the tool's overall diameter, the landing nipple also required milling to allow access. Therefore, a specially designed 4.412" mill bit was manufactured and run on a milling tool – a tool requiring tractor conveyance to provide weight-on-bit and counter the reactive torque. As the well had low deviation, the subsequent clean-out toolstring was run standalone (without tractor). One of the key factors governing the feasibility of conducting this operation on e-line was the overall toolstring lengths, where the lubricator height was limited to approximately sixteen meters. The e-line deployed milling technology – which produces a grinding action rather than cutting – successfully milled through the landing nipple and a ball catcher in four runs, thus increasing the internal diameter sufficiently to allow access for the clean-out toolstring. A well fluid column of about seven bar is required to enable operation of the suction tool. The clean out tool was configured with three bailer sections (seven max) for the first run, to determine sand recovery optimisation. Three different sizes of micron bailer filters are provided; prior knowledge of debris particle size is therefore advantageous. In this case, a slickline bailing sand sample had been recovered, which immediately aided filter choice. Seventeen bailing runs were conducted over five days (with the number of bailer sections increased to six), successfully recovering a total of 918 litres of sand, equating to about 2.4 tons. Ultimately, the process enabled perforation of two additional gas zones to increase production. The e-line toolstring, consisting of six different sensors and robotic tools, made this a more controllable and inherently safer operation than coiled tubing methods, as well as having a smaller footprint with reduced environmental impact. Operational details, including job planning and lessons learned will be discussed in the extended abstract.