First Offshore Hydraulic-Jet-Fracturing Multizone Completion ApplicationCase Study: Challenges and Lessons Learned in the Bozhong Oil Field,Bohai Bay, China

摘要

The first hydraulic-jet-fracturing multizone completion application was performed in an offshore high-permeability oil well located in the Bozhong oil field in Bohai Bay, China. A detailed case study is presented,highlighting operational challenges and lessons learned from the offshore multizone completion in theBozhong field. Most offshore high-permeability oilwell completions in the Bozhong field employ tubing conveyedperforation (TCP) followed by frac-packing as multi-zone completions, which is practical in this field.Unlike conventional multizone frac-pack completions, to run perforation guns, the perforating must becompleted first, followed by running isolation packers to complete the multizone frac-packing treatments.For hydraulic-jet-fracturing multizone completions, the hydraulic jetting tools are delivered to the targetdepth using drill pipe; following that, slurry fluid is pumped through the drill pipe to cut through the casingto create fluid flowing channels, which communicate with the pay zone formation. Lastly, the fracturingoperation is completed by pumping both proppant slurry through the drill pipe and cleaning fluid throughthe annulus simultaneously, which creates dynamic hydraulic diversion as functions of isolation betweenzones. After completing one treatment zone, the tools are pulled to the next target depth, repeating theprocedures, until the entire well is complete. After the fracturing treatment, the operator runs productiontubing and other accessories, putting the well into production as usual. A detailed completion design and step-by-step operational procedures were prepared based on welldata and work conditions to help ensure the effectiveness and safety of the offshore operation. Althoughsome challenges were encountered during the operation, it was overall successfully performed, andsignificant performance improvement was achieved. After being in production for months, the candidatewell has maintained a longer high-production-rate period than the offset wells completed using conventionalmultizone frac-pack completions.