Shaped Charge Patents 1942-1952: From Optimism to Solutions

Abstract

In the 1940s, the majority of research in America into shaped charge technology was performed by the US military and government laboratories. Information was largely classified. Shortly after the US Army declassified some details of this technology, extensive research and testing began in many American companies. Along with this came the filing of several patents. These US patents from the early years of shaped charge design reveal a transition from an almost naive optimism over the nascent technology to solutions for oilfield issues. A focus on the early claims and the issues with carriers and charge detonation reveals much in this regard. The Early Years—Optimism and Uncertainty A patent filed by E.I. du Pont de Nemours and Company in 1942 (2399211) typified the wave of optimism of shaped charge capabilities (this was not too unexpected, for du Pont manufactured the charges) (Fig. 1). Liners for the charges were not required, stated the document, but if they were present the metal slugs (“carrots”) produced from the detonation would be “projected at very high velocity through the perforation and into the adjacent strata.” In other words, the liner remnant was a positive consequence of the detonation. The patent also advocated the use of plastics or cardboard materials for the carrier, stating that the charge “may or may not be enclosed in a watertight container…they are generally insensitive to the action of water and impervious thereto.” Two years later, another du Pont patent (2605703) described a “novel and improved explosive device.” The document provided many details about shaped charge liners, but admitted that an understanding of why the devices worked was unclear and speculated the penetration was due to “pulverizing, molecular fragmentation or abrasion.” Even the liner was considered a contributing factor in the “net destructive effect,” but the patent admitted it “was not possible to determine this.” A Gulf Research and Development Company patent filed in 1945 (2494256) proposed a panoply of shaped charge configurations—as if to cover all possible uses. The document mentioned “numerous results of our experiments” that verified the penetrating power of the lined shaped charge and revealed the charges should be “provided with a suitable cover to pre vent any liquid entering the cavity (the liner).” The patent optimistically predicted that a slug would be “sufficiently small to pass through the hole in the casing and come to rest deep in the formation where it has negligible effect on the flow of fluids through the hole.”