Risk Evaluation Technique for Tubing-Conveyed Perforating

Abstract

This paper presents one application of a simulation tool that predicts tubing-conveyed perforating gunshock loads reliably. The tool enables completion engineers to evaluate the sensitivity of gunshock loads to changes in gun type, charge type, shot density, tubing size and length, rathole length, use of shock absorbers, and placement of packers, among others.The simulation tool described in this paper helps engineers to identify perforating jobs that have a risk of gunshock related damage, such as bent tubing and unset packers. When predicted gunshock loads are large, changes to the perforating equipment or job execution parameters are sought to reduce gunshock loads and the associated risks.Comparisons between predicted wellbore pressure and actual fast-gauge pressure data are available in related SPE articles. These comparisons show that predicted wellbore pressure transients are very reliable both in magnitude and time. Peak sustained pressure amplitudes at the gauges are on average within 10% of software-simulated values. For cases where shock absorbers were used, residual deformations of crushable elements correlate well with the peak axial loads predicted by the software. The software is able to simulate perforating job designs in a short time, which allows engineers to optimize perforation jobs by reducing gunshock loads and equipment costs.The ability to predict and reduce gunshock-induced damage in perforating operations is very important because of the high value of typical wells. With the software tool described in this paper engineers can optimize perforation jobs by minimizing the risk of gunshock-related damage and the associated non-productive time (NPT).

Study of Downhole Shock Loads for Ultra-Deep Well Perforation and Optimization Measures

“…The pressure difference between the gun and the wellbore produces shock waves in the wellbore fluid, propagating radially and axially up and down in a short time, leading to large fluid deformation and high-speed violent movement. The large-amplitude pressure waves that produce very large loads on the equipment, affecting the structural stability of the string system [5]. Due to the recent advances in well design and production techniques, tubing-conveyed perforating (TCP)-combined well testing is being increasingly used in challenging ultra-deep well completions [4].…”