Sun Qiang

Research and Application on the Technology of Ultra-short Radius Sidetracking Using Flexible Drilling Pipe

To increase the single-well drainage area, improve the single-well production rapidly, and reduce the drilling cost of horizontal wells, the flexible drilling pipe with universal joint structure was designed and the ultra-short radius sidetracking technology of the flexible drilling pipe with universal joint structure was developed. The windowing and sidetracking process were studied in this paper. With the analysis of the relationship between the length and diameter of flexible units and the curvature radius and diameter of the borehole, the appropriate diameter of flexible units with universal joint structure which is suitable for the 5 1/2″ cased hole was designed as 102 mm, with the length of a single joint designed as 0.15 m, and the turning angle of a single joint designed as 4.5–6°. The sealing test of the flexible drilling pipe showed that the sealing pressure of the flexible drilling short joints is 15 MPa, and the tensile test showed that the tensile pressure of the short joint is more than 100 t. The results of field test showed that the liquid production increased gradually from 1.2 to 5.2 m3/d and the oil production increased from 0.7 to 2.0 t/d, which means the liquid production and oil production have been effectively increased, and the injection-production relation of the well pattern has also been improved.