RIASSUNTO
SPE Members
Abstract
This paper reviews through-tubing recompletion technology, the isolation and/or addition of perforations in a wellbore without pulling the existing production equipment. Topics covered include through-tubing plugbacks and bridge plugs, coiled tubing cementing and through-tubing perforating. Several well case histories are also presented.
Introduction
Interest has surfaced in through-tubing recompletion technology. Through-tubing recompletions have been attempted throughout the history of the oil industry, primarily to cut costs. Ingenious plugbacks were attempted with crude bailers, surface dumps, etc. to try to eliminate unwanted intervals in the wellbore, without pulling the existing production equipment. Small diameter pipe (""macaroni tubing"") was used with limited success for cleanouts, spotting cement, fishing etc.
With the advent of better machining and steel milling processes in the Fifties and Sixties, continuous small diameter coiled tubing units began to appear in the oilfields, along with the first modern bridge plugs which could be deployed through production tubing. Many operators tried the new technologies, with mixed results.
Derisive remarks were made, including ""If you run it, you'll fish it"" and ""Don't use it in a good well"".
In the mid to late Eighties, important strides were made in the technology available for through-tubing recompletions. Larger and more reliable coiled tubing became available with improved metallurgy, better designed injector heads and BOP's, allowing sophisticated plugbacks and squeezes for a fraction of the cost of a conventional workover. Through-tubing bridge plugs have been run in thousands of wells with good results, and through-tubing perforating performance is approaching that of conventional guns.
Some of the advantages of through-tubing recompletion technology are:
1. Lower cost.
2. Existing production equipment is not removed from the wellbore
3. Ability to work on ""live"" wells with pressure.
4. Less risk with fewer personnel and shorter workovers.
5. Require less space and equipment on location.
All wells may be worked over through-tubing, but the following well bore characteristics increase the chance of a successful operation:
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