Casing Design And Casing-In Mechanics Analysis In Deep Water

Deep-water oil and gas resources in the world are rich. In recent years, deep-water oil and gas exploration has become the hotspot of world oil and gas exploration and development and new highlight in improving reserves and production, and it is also the inevitable development tendency of sea oil and gas exploration and the important strategic constituency of taking over oil and gas resources. But the existence of shallow drilling formation strength is low, narrow drilling fluid density window, and geological data and incomplete adjacent wells data are series of problems in deepwater drilling. The traditional design method is difficult to meet the need of well bore configuration. Therefore, the design of well bore configuration of deep wells and strength design are particularly important.Dual-gradient drilling, also known as dual-density drilling, is a new type of drilling technology for deep water drilling. On the basis of the existing deep-water drilling fluid density problem of the narrow window, the dual-density drilling fluid system is used for the design of casing string. Because deep water geological data is not complete, casing string is designed with the method of top-down design, compared to bottom-up design method. This design can effectively reduce the levels of the casing to ensure the safety of casing.During the design of casing strength, taking into account the special circumstances of deep water, security is a primary consideration. And improvement of safety factor triaxial strength design method is used. The method is a focused consideration on internal pressure and external pressure resistance strength check of the casing. Based on selecting appropriate safety factor, triaxial strength design method is used for internal pressure and external collapse strength check. The design may meet the demand for safety of well structure under the condition of deep water. according to basic equations of mechanics of the rod string of professer Li Zifeng, the tension-torque model of directional well drilling liner under various conditions is established.Finally, on the basis of theory research and field need, deep-water drilling casing string design software is developed by Visual Basic 2008, which is of great significance for guiding the field practice.