Modeling Air and Water Perforator Swell for Better Risk Management

Abstract

Summary A detonated-shaped charge fired from a perforating string or perforating gun not only perforates its targets, but also possibly causes excessive damage or swell to its carrier. Comprehensive understanding of the post-perforating conditions of either the perforator or perforator system is required if such damage and potential retrievability risks are to be avoided. In practice, the perforating design engineers do not have a well-established analytical tool to help understand post-perforating behavior of perforators. They have to rely on their own experiences and previous perforating histories to roughly estimate the swell or damage conditions of similar perforators. In this paper, the failure modes of continuously phased perforators for both gas well and oilwell applications are analyzed. Important factors concerning carrier serviceability are discussed. A method based on energy conservation is used to establish a swell model to predict the post-detonation conditions of the perforator. The model takes the total expendable energy from the explosives into account, relates it to the energy consumed by the functional and nonfunctional processes, and describes the relationship of energy distribution among them. A criterion is proposed to establish the serviceability of the perforators. Analytical results from the model are compared with the data collected from surface tests. The results indicate the model can reasonably predict the perforator swell and damage after detonation, and as such, be a useful tool that shortens the required time to develop future perforators.