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FLOWLINE RIGHT-OF-WAY SLOPE STABILITY STUDY IN KURDISTAN REGION, IRAQ
HKN Energy Limited operates several well site production facilities located in the Kurdistan Region of Iraq.In February 2020, it was determined that a section of flowline at one of these production facilities had deflected, presumably due to underlying ground movement. Fortunately, this deflection had not damaged the integrity of the flowline nor was there any product loss. HKN shut in oil activities from the well until the system could be evaluated and corrected. The purpose of this study is to assess the efficacy of dewatering for slope stabilization.
FINDINGS
Remediation work started on the slope in the spring and summer of 2020 and the flowline was returned to service in October 2020.
Following the remediation work, the slope was monitored by installing survey markers on the flowline sleepers and periodically recording coordinates and elevations using GPS surveying equipment. The remediation successfully stabilized the slope through the winter of 2020-2021, however movement of the sleepers and the flowline was again captured in March 2021. The sleepers and flowline continued to be monitored throughout the summer of 2021.
Piping stress analyses showed that stresses in the pipe were well below the yield point for horizontal movement; however, by September 2021, increasing vertical movement at the toe of the slope had resulted in vertical “bowing” of the pipeline – a more serious condition with respect to stresses in the pipe. As a result, the oil well was shut in, and the flowline was purged.
Following the shutdown, further investigation work was undertaken. First, a geotechnical site investigation including drilling logs, in-situ testing, and laboratory testing was carried out, followed by the installation of two trial dewatering wells. Following the results of the geotechnical investigation and trial wells, eight additional dewatering wells were drilled on the slope, creating a network of wells surrounding the flowline right-of-way.
CONCLUSION
In this study, dewatering proved effective for slope stabilization. All ten dewatering wells are operational and have been fitted with flow meters to measure volumes of water pumped. More monitoring programs should be investigated to ensure the effectiveness of the installed systems.