Abstract
Drilling multilateral (fishbone) wells in western Siberia is a common practice. A particular characteristic of these wells is the kickoff in the openhole horizontal section—no cement plug or whipstock is used. In the overwhelming majority of wells, it is economically impractical to perform tripping procedures twice—to change the bottomhole assembly (BHA) for the kickoff, and change it again for subsequent drilling. To reduce the well construction time, one requirement is to drill the horizontal section in one run.
Many operators have realized the advantages of using rotary steerable systems (RSS) for drilling multilateral wells that are becoming more complicated. During a well startup, the use of RSS to drill fishbone wells caused some concern about kickoff procedures. The operator had no experience with the process due to the analogue of adjustable kick-off sub (AKO) on the positive displacement motor PDM absence. The first kickoffs were made and resulted in a significant time increase compared to the same process with (PDM): 26 to 28 hours instead of 16 to 20 hours. Further experience with using kickoffs with RSS resulted in procedures and process improvements.
Based on the experience gained, a new kickoff procedure with RSS was tested at more than 20 jobsites in Western Siberia. A notable record was achieved on one of the multilateral wells on March 18, 2018 at the job for Lukoil-Zapadnaya Sibir Ltd. The kickoff in the open horizontal section was made in 1 hour 40 minutes, whereas the standard procedure took 20 hours 30 minutes. The time reduction of the kickoff process was 92% compared to the standard procedure, and 17% compared to the previous set record. The next stage of this technology will be its application in Eastern Siberia, with some modifications based on the lithostratigraphic section of the target horizon.
