| Popis: |
Horizontal drilling and multistage fracturing completions are becoming widespread practices in the development of Western Siberia’s low-permeability oil fields. More than 100 wells have been completed to date—with success from both operational and production perspectives. The majority of applications were applied in newly drilled wells, where it is possible to install openhole packers and frac ports for isolating fracture stages. The concept of multistage fracturing was transferred to old areas of brownfields, where sidetracks drilling was the main method of increasing oil recovery. Traditional sidetracks were associated with risks of production underachievement in low-permeability environments - even after stimulation treatments. The ability to drill sidetracks with a considerable horizontal section, and stimulating them with several fracturing stages would improve production significantly. However, slim wellbores of sidetracks significantly restrict completion option choice and abrasive perforating via coiled tubing (CT) becomes a universal enabler for multistage fracturing treatments. One of the greatest challenges in such a process is isolation between the stages. Fiber-enhanced proppant plugs were used for better proppant grains suspension, which sets the plug in the most efficient, homogeneous way. The first well was recently completed with this method. Three stages of fracturing stimulation were performed with CT abrasive perforation; fiber-enhanced proppant plugs were placed at the tail-in of the first two fractures. In both of the fractures, reliable isolation was achieved at first attempt. After all three stages were placed, wellbore cleanout with CT was performed, followed by nitrogen kickoff. Oil production has exceeded expectation by 30%. Multistage fracture (MSF) stimulation in the horizontal section of a sidetrack well completed with cemented liner with the utilization of abrasive perforating and fiber-enhanced proppant plugs has demonstrated unique value, as it is the only effective solution currently available for these conditions. The decision-making and candidate-selection processes, execution and lessons learnedare described. |
