Overview

Ledong 22-1 gas field, operated by CNOOC in South China Sea, has 4 long horizontal wells to be completed in its shallow gas bearing layer at 500m TVD, Ruifeng Petrotech solved the challenge with its OHGP (Open Hole Gravel Pack) system and PackSure shunt tube screens. In Aug. 2017, all 4 gravel pack jobs were successfully pumped.

Challenges & Solutions

The 4 wells have 700m of horizontal section in average at only 500m of TVD, that extremely narrowed the operating pressure window for gravel packing jobs, to avoid breaking down the formation and cause unwanted leak-off, a light weight proppant was selected for the job. Abundant simulations were run to find out the optimal pump rate, and emergency plan were practiced before the job to cope with cases of early screen outs.

PackSure shunt tube screen has also helped increase the odds of success. It has multiple shunt tubes installed between screen and base pipe, which act as a backup circulation path for the wellbore-screen annulus, in the cases of wellbore collapse and early sand bridging that the regular flow paths is blocked, the sand laden fluid will still reach the packing position through shunt tubes, and ensure an effective sand control.

The challenges of long horizontal wells in shallow reservoir is unprecedented in China, Due to the success of the 4 wells, Ruifeng Petrotech has been awarded more jobs with PackSure screens by customer.