How to Keep Tubing Sealed in Packers
- J.L. Logan (Baker Oil Tools Inc.)
- Document ID
- Petroleum Society of Canada
- Journal of Canadian Petroleum Technology
- Publication Date
- June 1963
- Document Type
- Journal Paper
- 77 - 83
- 1963. Petroleum Society of Canada
- 3.2.4 Acidising, 1.13 Casing and Cementing, 4.1.5 Processing Equipment, 4.1.2 Separation and Treating, 2 Well Completion, 3.1.1 Beam and related pumping techniques
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In many oil, gas, and injection wells. a string of tubing, sealed at itslower end in a packer, is used to isolate tubing pressures and fluids from thecasing. In multiple completions, two or more tubing strings are used to isolatezones. This paper presents a means of determining the best way to initiallyland the tubing in the packer to compensate for future anticipated wellconditions.
The equations in this paper were developed in a previous publication andhave been successfully applied to over fifty critical wells in the UnitedStates, Canada, and Europe. Many of these were deep, high-pressure,high-temperature, high-cost wells in which it was imperative that atubing-to-packer seal be maintained during all completion, remedial. andproducing operations. In some of these wells, it was important to keep thetubing as straight as possible to facilitate future wire line work.
The conditions of these wells have been grouped and tabulated so the readercan see some of the practical applications of the paper.
The bottom of a string of unanchored tubing in a rod-pumped well moves up onthe upstroke and down on the downstroke. In addition, the tubing graduallyelongates until the well reaches pumping equilibrium. Disregardingrod-to-tubing friction, vertical movement is caused by pressure and temperaturechanges acting on the entire tubing string. Knowing tubing and casing size,initial and final fluid densities and levels, and initial and final tubingtemperature, it is possible to calculate the extent of these verticalmovements.
Rod-pumped wells are generally familiar to the reader and are mentioned herebecause the freely hanging tubing string reacts in exactly the same manner tochanges in well conditions as does a string of tubing sealed, at its lower end,in a packer which permits free seal movement. A packer, however, may be setmuch deeper than a pump, and not only is a longer string of tubing exposed tothese changes but the changes may also be much more severe. Consequently, theamount of vertical movement is usually much greater.
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