Selection and Optimization of Floating Casing Technology in Field Application

Since horizontal wells and large displacement wells arose, it is crucial that the casing can be safely tripped to the target depth. Floating casing technology is one of the most effective methods to guarantee the safe insertion of casing in horizontal wells, especially in large displacement horizontal well. This article aims at selecting and optimizing the floating casing technology in practice. Firstly, it determines the type of well by calculation in order to confirm that whether floating casing technology is needed and what kind of technology needs to be applied. Secondly, it determines the position and quantity of floating collar by trial algorithms, multi-factor analysis and other methods. Based on102 field applications, the following conclusions are driven: 1) The floating casing technology significantly improved the casing penetration capacity of horizontal wells and large displacement wells, and reduced the rate of accidents; 2) Optimized calculating the position and quantity of the floating collar is needed, it was ensured that the opening pressure of the floating collar meet the designments so that the casing was smoothly tripped to the target depth; 3) It guaranteed the casing operation safety and cementing operation success without repeated plugging. The constant pressure bursting disc sub-floating casing technology achieved the full diameter of the wellbore by optimizing the collar device. To sum up, the floating casing technology solves the problems of complex traditional process flow, poor sealing of the pipe string, and inability to achieve full bore by selecting and optimizing, it also facilitates the upcoming fracturing application.