Expandable Casing Structure Design And Its Mechanism

This thesis belongs to the project of Petroleum Technology Innovation Fund of CNPC "the New Technology Study of Cementing-Well Completion with Solid Expandable Tubular" and is part of the project of National Nature Science Fund (NO. 50074025) "the Destroy Mechanism Study of Casing in Complex Formation Based on Numerical Simulation".The solid expandable tubular technology has been successfully applied in commercial application at abroad, and has obtained compelling achievement. However, the study of solid expandable tubular technology is only limited to mechanism study and experiment in China. Based on the existent search fruit, this thesis studied the structure design and mechanism of solid expandable tubular. Detailed studied the structure of the expansion cone, the effect of friction coefficient on the expansion operation, the metal flow rule of expandable tubular during the course of expansion, the structure design of connector for an expandable casing string and so on.In this thesis, by means of the computer finite element simulation and with the theoretic fundament of elastic-plastic mechanics, much simulation analysis was implemented on the structure design of solid expandable tubular and compared with in-situ expansion operation at abroad and the experiment results in china, a series of important conclusions were obtained: (1) Comparing to the multi-stage expansion cone, the single stage expansion cone is advantaged to the expansion. The extent of expansion varies with the optimal degree of cone, and obtained several values of optimal degree of cone on different extent of expansion. (2) The metal flow rule of the expandable tubular is closely related with the friction coefficient and extent of expansion. (3) Conventional connector for casing string can't meet the demand of seal and connection in solid expandable tubular and presented a new thread structure for an expandable casing connector.The results of this thesis provided theoretic fundament for the structure design of expandable tubular and have important meaning in the research and exploitation of the solid expandable tubular technology.