Tripping Friction Model for Multi-Stage Fracturing and Completion String in Horizontal Well

Abstract

The structure of multi-stage fracturing completion string in horizontal well is complicated. The downhole tools such as packers and sliding sleeves whose dimensions are very close to the size of the borehole, and the completion string has strong stiffness as well. Thus, it leads to larger frictional restriction when running string. Based on the above reasons, it is essential to calculate the tripping capacity before the strings running into the well in case of sticking off. However, calculation errors of conventional string tripping models are relatively larger. This paper took the structure of multi-stage fracturing completion string into consideration, divided completion string by contact points between string and borehole to establish the stress and bending model of the string between two contact points, and established the tripping friction and hookload model for multi-stage fracturing completion string. An applied example of multi-stage fracturing horizontal well in Hong 90-1 block of Jilin Oil Field shows that the created model in the paper is more accurate. The accuracy of hookload while the string running in form curved section to bottom is 95.80%. The established model is more accurate and reliable. It can be used to estimate the tripping ability of the multi-stage fracturing completion string. Key words : Multistage fracturing; Tripping; Tripping friction; Mechanical model