Fills Cleanout With Coiled Tubing in the Reverse Circulation Mode

Fills Cleanout with Coiled Tubing in the Reverse Circulation Mode Jeff Li; Jeff Li BJ Services Company Search for other works by this author on: This Site Google Scholar Bernard H. Luft Bernard H. Luft BJ Services Co. Canada Search for other works by this author on: This Site Google Scholar Paper presented at the IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, November 2006. Paper Number: SPE-102661-MS https://doi.org/10.2118/102661-MS Published: November 13 2006 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Li, Jeff, and Bernard H. Luft. "Fills Cleanout with Coiled Tubing in the Reverse Circulation Mode." Paper presented at the IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, November 2006. doi: https://doi.org/10.2118/102661-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition Search Advanced Search AbstractRemoving sand fills from wellbores is one of the major applications for coiled tubing (CT). For the fills cleanout process, the fluid could be circulated in two different modes: forward circulation and reverse circulation. In the forward circulation mode, the carrying fluids are pumped through the CT down to bottom and flowed back to surface in the CT/casing annulus. For reverse circulation, fluids are pumped down the CT/casing annulus and back up the coil. In many cases with large completions and low reservoir pressures, the forward circulation mode cannot effectively clean the fills out of the annulus with only a limited available flow rate or without circulating expensive gel fluids, especially for the heavier particulates in deep and/or highly deviated wells. Due to the smaller flow areas and therefore higher velocities, fills may be more readily transported inside the CT flow channel. Therefore, reverse circulation may be an option to overcome the above constraints associated with forward circulation.Several major risks for reverse circulation with CT include coil collapse, loss of well control and sand bridging in the coil. Controlling the rate of penetration (ROP) of the CT into the fill is very critical for the reverse circulation sand cleanout process. There is a lack of knowledge on the effect of as well as optimum ROP during reverse circulation. In this paper, the maximum ROP for different sand types at different deviated angles and water flowrates for reverse circulation cleanouts are investigated with a full scale flow loop test facility. Based on these test results, empirical correlations have been developed and incorporated into an existing proprietary solids transport computer algorithm, which can now be used to optimize the hole cleaning process for both the forward and reverse circulation modes of solids transport.IntroductionSeveral wellbore cleanout methods have been developed over the years. One of the most common operations is running in with coiled tubing and circulating the solids out with a liquid or multi-phase fluid through the annulus between the CT and wellbore (i.e. forward circulation, Fig. 1). Solids tend to settle and form an equilibrium bed on the low side of the wellbore in highly deviated or horizontal wells. This problem is exacerbated by the eccentric annular flow path created with the CT entering deviated wellbores. Fluids with enhanced solids suspension properties tend to have poorer solids reentrainment abilities once a stationary solids bed has formed. The conventional approaches to removing the solids bed involve using higher flow rates, or employing exotic and costly fluids, neither of which ensures complete fill removal in every case.Based on prior comprehensive research1–6, an effective CT sand cleanout methodology utilizing the forward circulation mode has been developed, patented7, and verified during numerous field operations8–13. This proven sand cleanout process entails a down hole wash tool and a sophisticated computer based methodology for CT deployment in vertical, deviated and horizontal wells. The preferred down hole tool incorporates fluid nozzles with switchable forward and backward facing jets. By selecting the backward facing jets and controlling the pull-out-of-hole (POOH) speed (at rates determined by the associated particle transport software), the settled sand bed can be "swept" out of the hole with near 100% efficiency.However, in some cases involving large completions in deep and/or highly deviated wells, the forward circulation mode cannot effectively clean debris fills out of the annulus with the limited flow rate available or without resorting to expensive gel fluids8. Due to the smaller flow areas and higher velocities, fills can be effectively transported by the internal CT flow channel. Therefore, reverse circulation presents an alternative clean out mode that could overcome the above limitations associated with forward circulation. Keywords: production monitoring, Coiled tubing operations, circulation mode, Reservoir Surveillance, Upstream Oil & Gas, concentration, forward circulation, Carbolite, production logging, circulation Subjects: Well & Reservoir Surveillance and Monitoring, Production logging, Completion Installation and Operations, Coiled tubing operations This content is only available via PDF. 2006. Society of Petroleum Engineers You can access this article if you purchase or spend a download.

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