World's First Fishbone Openhole Gravel Packing Using Shunted Gravel-Pack System: A Case History from Bohai Bay, China

Abstract

For the first time in China, shunted gravel-pack screens have been used for two long, fishbone type, multilateral openhole sand control wells in 2022. Shunt-tube systems have been widely used in cased hole and openhole gravel-packing operations in the past few decades as the most reliable sand control solution. However, this is the first shunted gravel-pack screen application in an openhole main bore with fishbones. This successful drilling and completion methodology can be used in this field and other locations to increase the well production rate by enlarging the reservoir contact area with fishbones without adding much capex to drilling and completion operations. Challenges and solutions for two wells included running the completion tool string to total depth in complicated well configurations, optimized operating procedures, gravel-pack pumping design for complicated scenarios resulting from fishbones, and onsite operations. The work included a detailed analysis of post-job data. The uncertainties of fluid loss and wellbore stability around the fishbones and the potentially unstable shale streaks in the 600-m-long openhole sections became challenging during gravel packing. Bridging was observed when slurry arrived at the openhole, and shunt tubes were activated much earlier than expected for both wells. Most (85%) of the packing was pumped through shunt tubes for the first well. High wellhead pressure caused by shunt friction was well managed to make sure as much gravel as possible was pumped. For the second well, 67% of the packing was pumped through shunt tubes. As there were no bottomhole gauges ran on wash pipes, post-job analysis was mainly based on volumetric data to analyze the potential packing sequence for the two wells. Post-job data analysis indicated that early gravel bridging might be attributed to potential hole collapses around the lateral and shale sections. Without the use of alternate shunt-tube screens and proper carrier fluid, the job would likely have resulted in an incomplete packing and failed sand control operation. Packing efficiency was 123% and 146%, respectively for the two wells, and the oil production rate was two times higher than that expected.