A New Jet Perforating Charge Eliminates Carrot Plugging
- R.L. Robinson (Jet Research Center Inc.) | Pete De Frank (Jet Research Center Inc.) | R.F. Hatfield (Jet Research Center Inc.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- April 1960
- Document Type
- Journal Paper
- 73 - 75
- 1960. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 2.2.2 Perforating, 2 Well Completion, 1.6.9 Coring, Fishing, 5.3.2 Multiphase Flow
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Production equal to or greater than open-hole completions is possible through perforated completions if the flow paths throughout the perforations are free of obstructions. Previous investigations have indicated that, in some cases, maximum productivity is not obtained due to plugging of the perforations with debris from the wellbore fluid and/or debris from the perforating process. Control of wellbore fluid and proper well completion techniques are very important in the elimination of perforation plugging. Selection of properly designed perforating equipment also is quite important for maximum well productivity.
Studies made with the use of the perforation flow laboratory, in which perforating tests are run under simulated well conditions, have shown that perforation plugging occasionally occurs. Plugs in perforations result from various causes. One of the contributors to plugging that can be controlled by the perforating device is the slug or carrot resulting from jet perforating. This condition has undergone extensive study, and previous developments have resulted in a decrease in carrot size-but not in complete elimination. It was felt that, if a method of completely eliminating the carrot could be found (with charge performance equal or better than previously obtained), a significant contribution would have been made. Such a charge has been developed and is reviewed in this paper.
Theoretical Considerations of Carrot Elimination
There are several popular theories of how a shaped charge jet is formed. One of these is the hydrodynamic theory, wherein the liner is treated as a fluid under the impact of the explosive forces. Another is the spalling theory, where the interaction of shock waves in the liner causes small particles to be torn from the inner surface of the liner and projected at high velocity toward a common focal line to form the jet. It is not unreasonable to assume that both of these theories may be partially correct. For purposes of our discussion, it is simpler to use the second theory.
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