Technological Process of the Composite Casing Drilling Technology in Deep-Water Riserless well Construction

The composite casing drilling technology in a deep-water riserless well construction is the technology providing drilling of the tandem borehole composed of the surface conductor borehole and the surface casing borehole in a one-trip drilling operation. The composite casing is put into place and is cemented in one trip. The composite casing drilling technology not only combines the advantages of the drilling method and the jetting technology but also overcomes the limitations of both technologies. The composite casing drilling technology has been successfully applied in the Mozambique block A drilling projects. The results of the field application show that this technology is able to provide secure and efficient drilling operations, which can considerably reduce the installation time and the costs. In this paper, based on the example of application in the Mozambique block A gas field, the process of the composite casing drilling technology is described in detail. Then, the authors analyze the field conditions and put forward an optimization method. The optimization method is applied to select the optimal technology for drilling and installing the surface conductor and the surface casing.