This paper reviews the sand control practices used in an offshore Malaysia field, including execution of the longest single-trip multizone cased-hole gravel pack in Malaysia, the challenges faced, and the lessons learned.

PETRONAS is currently developing an offshore field in Malaysia with wells designed to obtain medium-to-high production rates and be completed as gas-lifted dual-string producers. The lower sandface completion design was to gravel pack the lower and middle zones on a single run and selectively produce through the long string. The upper zone was then to be gravel packed and produce through the short string. Because of the long perforated intervals and exceptionally long distance between the producing zones, as well as different pressure profiles of the layers, shunt tube technique was identified as being the best practical method to overcome the operational challenges. The target reservoir is a laminated and multilayer sandstone formation. The lower and middle zones were gravel packed simultaneously with gross-producing intervals to 950 ft (the shaly section between the zones up to 600 ft). The upper zone was gravel packed separately with a gross perforated interval length to 775 ft. Due to the different pressures in the multiple zones, loss and crossflow control was a design requirement.

The project imposed a number of challenges, including gravel packing extremely long intervals while aiming to achieve suitable perforation packing efficiency in unconsolidated and soft sandstone formations and also providing the possibility of selective production during the life of the wells. The proposed solution to overcome these concerns consisted of combining shunt tube technique with a three-way sub-concentric completion system.

Five wells using this design have successfully been completed in this project with sand-free production rates exceeding expectations.

The proposed solutions and the lessons learned in this project could change the sandface completion practices for multizone and long intervals in the offshore Malaysia fields. The techniques used in this project resulted in considerable rig-time savings, lower skin, and better productivity through improved perforation packing efficiency compare to the conventional methods.

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