Carbonate plugs in drilling of multilateral wells

Abstract

The major problem encountered during drilling multilateral wells is the temporary isolation of each lateral while drilling other. Two solutions have been introduced from the oil industry namely, mechanical isolation such as retrievable packer and carbonate plug. Retrievable packer faced different problems such as setting and retrieving due to debris barrier. Carbonate plug is a new technique that is introduced to isolate each lateral separately and to replace the inflatable casing open hole packer in horizontal wells. This paper discusses the possibility of using carbonate plug. It introduces a laboratory study of plugging effects of the carbonate plug through flooding experiments on Berea sandstone cores and a carbonate formation of a Saudi reservoir. It also studies the permeability reduction due to the carbonate plug and how to restore the original permeability in forward and reverse direction. The results show that the carbonate plug caused a reduction in the sample permeability. However acid treatment was successful in restoring the original permeability, so that the remained reduction did not exceed 5% of original permeability.