Live Fiber-Optic Telemetry Downhole Measurements on Coiled-Tubing-Enabled High-Efficiency Sand Cleanout in a Subhydrostatic Well for theFirst Time in the Gulf of Mexico
Gulf of Mexico (GoM) reservoirs consist mainly of unconsolidated sandstones. Elevated production rates and high near-wellbore fluid velocities increase the possibility of dragging the unconsolidated sand grains into the wellbore and surfaceproduction equipment. Formation sand invasion into wellbore is a common problem in the GoM, especially in wells notcompleted with sand control features or wells where initial sand control failed. Wellbore sand cleanouts, therefore, representthe majority of coiled tubing (CT) interventions in the GoM. As the reservoirs mature, the number of through tubing wellinterventions (TTWI) in sub-hydrostatic wells is constantly growing. These types of wells cannot sustain a full column offluid which presents a significant challenge to maintain circulation and sufficient annular fluid velocity required to transportthe solids to surface. Nitrified and foamed cleanouts can provide at-balance or slightly over-balanced downhole conditionsnecessary to minimize the fluid losses into formation. Nitrified cleanouts are normally considered as more cost effectivesolution which is quite important since most of the sub-hydrostatic wells are very marginal producers. However, planningand execution of nitrified jobs require accurate well information which is not always accurate or available. This drives theoperators to make the most common decision; to utilize the more expensive and extensive cleanout technique - the foamedcleanout - in order to ensure job objectives with reduced risks.Real-time downhole measurements provided by a fiber-optic enabled telemetry CT helps overcome the typical challenges andoperational risks associated with sub-hydrostatic well cleanouts; it also helps reduce the overall operational costs by makingthe job more efficient in terms of time, equipment and product usage. This paper will present a case study of the firstoptimized CT sand cleanout in the Gulf of Mexico.
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