Industry First: Shunt Tubes Open Hole Gravel Pack Completion Through 9-5/8" Milled Casing Window in ACG Field, Azerbaijan

Abstract

Azeri-Chirag-Gunashli (ACG) is a giant field located in the Azerbaijan sector of the Caspian Sea. The major reservoir zones are multi layers sandstone formations with oil column up-to 1000m, and weakly consolidated where Open Hole Gravel Pack (OHGP) completions have become the standard design for production wells. Development began in 1997 and to date more than 130 high rate OHGPs have been installed. Once existing wells has been uneconomically to be produced, a Sidetrack or Up-Hole Recompletion (UHRC) will be performed. The standard 9-5/8" sidetrack technique will be done by drilling new section, installing and cemented a 7-5/8" liner, then drilling 6.5"x8" hole in pay zone followed by running 4" Shunted Screen and gravel packing. Previously C&P technique has been used for UHRC option but it was producing at limited drawdown and quickly sand up when water break through. Cased Hole Gravel Pack (CHGP) technique has been trialed as UHRC option in the past 2 years but has limitation of the number zone & length can be perforated which resulted in leaving some zones unperforated behind casing. A new concept of UHRC has been designed and successfully tested. This concept consists of sidetracking into the overburden, drilling to TD and removing 7-5/8" liner section. Shunted screen then deployed into open hole through a cased milled window followed by gravel pack operation. While standalone screens have been deployed through cased milled windows before, deploying shunted screens through a cased milled window followed by an OHGP is an industry 1st. This technique delivers the well 20 days earlier compare to standard Sidetrack OHGP well due to removal 7-5/8" production liner section. This technique is also give advantage over stacked CHGP option because can provide higher k*h access, can handle high levels of differential depletion within the completed interval and has the potential to unlock up lot more well candidates to allow and deplete the reserves from overlying reservoirs. This paper will also describe window and well design to deliver successful Shunt Tubes OHGP installation with this technique.