A Practical Approach to Jarring Analysis

Abstract

Summary To fulfill the practical needs of drilling personnel routinely involved in jar selection and use, a computer program based on stress-wave theory was developed. This approach provides an accurate, fast, and simple-to-use method for jar selection and optimization. It eliminates the need for large computational facilities, long solution times, and a high level of engineering expertise that are commonly associated with state-of-the-art transient dynamic finite-element methods (FEM's). The program's accuracy was verified through comparisons with FEM results. The program produces a large matrix of results over the specified range of jarring variables within a few seconds of processing on a personal computer. The results provide an insight into the interaction between jarring variables and guidance in the optimum jar placement. Some application results are presented to show its usefulness in assisting drilling personnel in jar selection and placement. Typical results for the bottomhole assemblies (BHA's) containing heavyweight drillpipe (HWDP) show some interesting and not-so-obvious problems in such assemblies.