A New Approach Toward Elimination of Slug in Shaped Charge Perforating
- J. Delacour (Societe de Prospection Electrique) | M.P. Lebourg (Societe de Prospection Electrique) | W.T. Bell (Schlumberger Well Surveying Corp.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- March 1958
- Document Type
- Journal Paper
- 15 - 18
- 1958. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 5.3.2 Multiphase Flow, 2.2.2 Perforating
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Since the advent of the perforation flow laboratory, increased attention has been focused on new designs of shaped charges as applied to oilwell perforating. Data derived from the flow laboratory, in which charges are subjected to simulated down-hole tests, indicate that serious perforation plugging often exists due to the entrance of slugs into the perforated hole.
The slug or "carrot" is an intrinsic part of the jet process and its adverse effect is inherently characteristic of many commercial shaped charges which otherwise exhibit excellent performance properties.
Numerous approaches have been tried throughout the industry in an effort to prevent this flow-impeding slug from entering the perforated hole. Yet, publicly conducted tests indicate that none of these devices are entirely successful when applied under the clearance and pressure conditions for which the charges are designed. This paper deals with a new, direct approach toward the elimination of the slug or carrot in shaped charge perforating.
Herein is described a newly developed bimetallic liner for shaped charges, which when fired under pressure leaves no slug in the perforated hole and yet maintains the high performance of the conventional-type charge.
During the past few years the testing of shaped charge tools, as applied to oilwell perforating, has evolved from simple surface shooting to tests conducted in a flow laboratory in which a study of the charge could be made under simulated down-hole conditions. In the flow laboratory, pressures and temperatures were elevated prior to firing the charge into a target of medium-hard sandstone material. An elaborate system was devised for firing the charge under various fluids and differential pressures. Provisions were made for actually "flowing" the perforated hole under controlled conditions. It was at this point that the term slug or carrot really emerged into oil-well perforating vernacular. While it had been noted that a slug of charge liner material often entered the perforation, these plugged test targets had drawn little attention. Now in the flow laboratory, it was found that this obstructing slug reduced the resultant flow through the perforation to as little as one-half that normally expected! It was then clear that the slug must be either eliminated from the shaped charge entirely or reduced to such proportions that it would be ineffective in plugging the perforated hole.
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