Coiled Tubing Used To Fish Coiled Tubing From a Live Gas/Condensate Well
- Karen Bybee (JPT Assistant Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- June 2010
- Document Type
- Journal Paper
- 65 - 66
- 2010. Society of Petroleum Engineers
- 0 in the last 30 days
- 75 since 2007
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This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 129507, "Fishing Coiled Tubing From a Live Gas- Condensate Well With Coiled Tubing While Under Production," by B.I. Kang, B.S. Murugappan, SPE, O.K. Kwon, and G.J. Sinn, Korea National Oil; I. Foster and L. Robinson, Weatherford; and J.B. Elliot, SPE, R. Hampson, and B.L. McKinnon, Halliburton, originally prepared for the 2010 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, 23-24 March.
This case study examines the techniques required to recover a coiled-tubing (CT) fish from a live gas/condensate well by use of CT. These procedures recently were implemented offshore Vietnam, where an extremely fluid-sensitive formation prevented killing the well because the formation likely would not have recovered. Using the techniques described in the full-length paper, a 1.50-in., 9,177-ft-long CT fish was recovered from a well while keeping the well on production.
CT is used around the world as a common well-intervention technique, and its scope of usefulness extends into many areas, including CT drilling, logging, fishing, milling, debris cleanout, and gas lifting. As technology progresses, so does the usefulness of CT to the industry as a whole, and the physical boundaries of what CT can achieve are being pushed constantly. This can lead to an unplanned failure of the string while in the well.
When a CT string parts in hole, the resulting fishing operation can be dangerous and complex; as such, standard practice dictates that the well be killed as a first step to recovering the parted string. However, killing the well can introduce pressures and foreign fluids to any open formations, which can lead to permanent or long-lasting negative effects on well performance.
While using CT for logging the production of a well offshore Vietnam, an uncontrolled gas breach at surface required a complete emergency shut-in of the well, and as a result, 9,177 ft of 1.50-in. CT was sheared at the blowout preventer (BOP) and dropped 5,489 ft to total depth. The deviation of the well varied between 30 to 57°.
At first, it was feared the fish might have buckled catastrophically after impacting the bottom of the well, in which case recovery would be nearly impossible. However, the top of the fish was later found to be at 5,538 ft from surface (just 49 ft below the expected depth of 5,489 ft); there-fore, only slight damage was expected to the bottom of the fish.
As is the usual first step to retrieve a difficult fish, it was proposed that the well be killed. However, the client company refused, stating that the extremely fluid-sensitive formation would likely not recover from any fluid damage and thus that killing the well would result in the loss of the well itself.
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