The "RPR" - Retrievable Pressure Retainer
Authors: Clark William H. , Ikeler Ken E. 
Published: December 2007

This paper was prepared at the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to publish is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.

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Many of us in the Aquifer gas storage put syphon strings (tubing) in wells to assist in de-watering the well during gas withdrawal. There is usually some remedial work and/or logging to be performed on these wells every year normally during the injection period. Sometimes even during withdrawal period, it is necessary to pull the tubing out of a well. Since most of the storage fields in the Midwest are remote from service equipment for pulling tubing under pressure, it necessitated the development of an alternate method - the "RPR" Method". For this method it is necessary to have a cable tool unit with a 65' mast, the usual tools and two ram-type blowout preventers with a hydraulic closing unit. Usually cable tool unit is available any time of the year, and even though the cost of this method is very little less than a snubbing unit, the availability of it at any time of the year is a big plus factor. There are some limitations to the use of the "RPR", however it is compatible to most well conditions. It is thought that this tool and method is applicable in areas other than in gas storage, because of the similarity in remedial jobs. The fact that the formation is not contaminated from having a well killed, that a master valve can be changed without setting a permanent bridge plug, that certain logs can be run by loading the hole with water on top of the "RPR" and that moderate to large casing or collar leaks can be located by pressure test all make the "PRP" a very useful tool.

"RPR" - RETRIEVABLE PRESSURE RETAINER

In aquifer storage, it is necessary to handle a considerable amount of water during the withdrawal cycle. If the wells could be produced according to normal reservoir engineering produced according to normal reservoir engineering criteria, very little water would be produced; however, peak day demands alter these produced; however, peak day demands alter these criteria. To keep a well from loading up and killing itself with water, it is necessary to install syphon strings - or tubing - in the well, produce the gas through the annulus between the tubing and casing and the water through the tubing.

Quite often remedial work on wells is necessary, and it is impractical to kill the wells because of the danger of formation damage as well as the cost of the work over fluid. When the well is equipped with an "RPR" Retrievable Pressure Retainer it is possible with only a cable tool rig to pull the syphon string, to complete the remedial work and to rerun the syphon string without the danger of having formation damage. It is possible, of course, to snub tubing out of the well under pressure, and we have handled many tubing strings in this fashion.