Chen 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.

Effective Application of Solid Expandable Tubular During the Enhancement of Heavy Oil Recovery in China, Lessons Learned and Experience Shared

As the traditional thermal recovery became less effective in exploring the heavy oil reservoirs, some newly developed techniques such as chemical flooding, SAGD and HDCS are demonstrating their advantage in the recovery process in China. However, the ever increasingly used new techniques often compromised severely the well integrity as the flow of extremely high temperature fluid or gas caused quick damage to casing, leaving the wellbore less reliable. This compromise requires urgently a workover strategy that would maximize the well’s life span and guarantee the effectiveness of new techniques. Solid expandable tubular (SET) was field-proven in casing patching activities, but its application in the heavy oil recovery has not been attempted due to severe temperature challenge. We made innovations on the traditional structure of SET and got valuable results. The tubular after expansion was integrated with the original casing as a whole and the rubber was removed in-between, the wellbore size was maintained utmost and the casing was further strengthened. Meanwhile the expansion cone was put outside the tubular which is a big step forward in SET structure. Indoors experiments demonstrated sound performance of the new structure in the simulative temperature of 350 ℃, the plan for the field application was optimized based on the lessons collected in this experiment. High temperature well applications by SET were carried out in Liaohe oilfield which is famous for its heavy oil resource in China, and the detailed process as well as the outcome were compared and analyzed, finally the conclusions were drawn as a result of the whole study. We expect our work will help expand this enabling technology to better facilitate the enhancement of heavy oil recovery and maintain solid well integrity during the heavy oil production. Key words : Solid expandable tubular; Heavy oil recovery; China