Investigation of key problems of clustering perforation string running in horizontal well with unconventional oil-gas reservoirs

Abstract

Currently, there are two main clustering perforation methods: coiled tubing-conveyed perforation (TCP) and cable-conveyed perforation (CCP). To improve the efficiency of CCP strings in wellbore pass-through capacity problems, considering wellbore geometry constraints, pipe string variable cross-section, flexible tool deformation, and other factors, the pass-through capacity analysis model of the perforating tool string was established and solved by geometric analysis and beam-column theory. Aiming at the running depth problem of a TCP string, considering the influence of the buckling effect, a model of coiled tubing running depth was established by the infinitesimal method. The field test data were used to verify the effectiveness of the two models. The effects of well trajectory, perforating string size, casing inner diameter, and coiled tubing size on the pass-through capacity of the CCP string and running depth of the TCP string were explored. The results indicate that with the increase of perforation string size or the reduction of casing inner diameter, the pass-through capacity of CCP string decreases; with the increase of coiled tubing specification, the running capacity of TCP string is improved. The work presented in this paper provides an effective analysis method and theoretical guidance for clustering perforation jobs in the field.