Dynamic FEA Buckling Model for Snubbing
- Kenneth Ray Newman (CTES/Varco) | Charles C. Overstreet (Cudd Pressure Control) | Pierre Beynet (BP)
- Document ID
- Society of Petroleum Engineers
- SPE/ICoTA Coiled Tubing Conference & Exhibition, 4-5 April, The Woodlands, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2006. Society of Petroleum Engineers
- 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.7.5 Well Control, 4.1.2 Separation and Treating, 1.6 Drilling Operations, 3 Production and Well Operations, 1.6.1 Drilling Operation Management, 5.6.1 Open hole/cased hole log analysis, 3.2.2 Downhole intervention and remediation (including wireline and coiled tubing), 1.7 Pressure Management, 4.2.3 Materials and Corrosion
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A dynamic finite element analysis (FEA) calculation engine has been developed and is being used to solve specialized well intervention problems. This paper summarizes the theory used in this engine, and documents two of its applications. The first application is modeling the buckling behavior of pipe (or a bottom hole assembly) being snubbed through a packer. The second application is wireline being run from a boat to a subsea well to perform an intervention. The first step in this intervention is to jar the plug out of the tree.
A dynamic FEA engine has been developed for modeling several well drilling and intervention situations. The initial model is for analyzing pipe in a wellbore, discussed in reference 1. The second model is for analyzing well intervention stack stability and stresses, discussed in reference 2. This paper discusses two additional applications which use variations of the same FEA modeling capability. As this powerful calculation technique is refined and applied, many more complicated well drilling and intervention models can be developed.
The theory for this FEA engine has already been discussed in references 1 and 2. The major addition to the theory discussed in this paper involves buckling of a pipe and the large displacements needed to model the behavior of wireline in the ocean between the boat and the subsea well.
When pipe, or a bottom-hole assembly (BHA), is being snubbed into a well, large compressive forces are applied to push it through the packer into the well. These forces often cause the pip to buckle in the surface equipment. Anti-buckling guides are often used to prevent excessive bending. Failures have occurred, especially when snubbing packers into a well.
A modeling tool was developed which calculates the maximum bending and stress in each component of the pipe of BHA. Intervening in subsea wells from a boat is much less expensive than using a rig to perform the intervention. There are many questions about how the wireline will behave with the ocean currents, especially when performing an operation which requires precise force/displacement control such as operating jars. The current causes a significant lateral displacement of the wireline as it passes through the water. If there is a sudden change in tension of the wireline at surface, will the tension be translated through the wireline to the well, or will the motion of the wireline and its shape in the water absorb the change in tension? Will the operator on the boat be able to determine from his surface tension indicator when the jars have fired, when the plug has released, etc? How should the depth measurement be corrected for the lateral displacement of the wireline in the water? If the boat is moving up and down, how much will the wireline tools move up and down in the well? A modeling tool was developed to answer these types of questions.
|File Size||349 KB||Number of Pages||9|