The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform

Gilberto Bruno Ellwanger - One of the best experts on this subject based on the ideXlab platform.

  • Wellhead axial movements in subsea wells with partially cemented Surface Casings
    Journal of Petroleum Science and Engineering, 2020
    Co-Authors: Charlton Okama De Souza, José Renato M. De Sousa, Gilberto Bruno Ellwanger
    Abstract:

    Abstract In subsea wells, the Surface Casing String should be fully cemented but, eventually, this is not possible due to the long length of the String and/or the soil characteristics. As the Surface and the structural Casings are the foundations of any subsea well, a partially cemented Surface Casing may allow significant wellhead movements, which affect the structural response of the well. This article, therefore, addresses the prediction of wellhead axial movements considering subsea wells where the Surface Casings are partially cemented. These movements are assessed with a multi-String model composed of nonlinear springs and bars that represent the Casing Strings. Nonlinear hysteretic t-z curves represent the soil and a developed finite element (FE), which combines these curves and the stiffness of the structural Casing String, represents this String. A typical subsea well is analyzed assuming different soil-structural Casing conditions and uncemented lengths. These analyses evidenced the significant impact of the uncemented length on the wellhead movements and on the stresses in the Casing Strings, especially if the structural Casing load capacity is overcome. Comparisons with results from an analytical and a FE model developed in a commercial software showed good agreement and highlight the need to adequately modeling the structural Casing-soil interaction.

Charlton Okama De Souza - One of the best experts on this subject based on the ideXlab platform.

  • Wellhead axial movements in subsea wells with partially cemented Surface Casings
    Journal of Petroleum Science and Engineering, 2020
    Co-Authors: Charlton Okama De Souza, José Renato M. De Sousa, Gilberto Bruno Ellwanger
    Abstract:

    Abstract In subsea wells, the Surface Casing String should be fully cemented but, eventually, this is not possible due to the long length of the String and/or the soil characteristics. As the Surface and the structural Casings are the foundations of any subsea well, a partially cemented Surface Casing may allow significant wellhead movements, which affect the structural response of the well. This article, therefore, addresses the prediction of wellhead axial movements considering subsea wells where the Surface Casings are partially cemented. These movements are assessed with a multi-String model composed of nonlinear springs and bars that represent the Casing Strings. Nonlinear hysteretic t-z curves represent the soil and a developed finite element (FE), which combines these curves and the stiffness of the structural Casing String, represents this String. A typical subsea well is analyzed assuming different soil-structural Casing conditions and uncemented lengths. These analyses evidenced the significant impact of the uncemented length on the wellhead movements and on the stresses in the Casing Strings, especially if the structural Casing load capacity is overcome. Comparisons with results from an analytical and a FE model developed in a commercial software showed good agreement and highlight the need to adequately modeling the structural Casing-soil interaction.

José Renato M. De Sousa - One of the best experts on this subject based on the ideXlab platform.

  • Wellhead axial movements in subsea wells with partially cemented Surface Casings
    Journal of Petroleum Science and Engineering, 2020
    Co-Authors: Charlton Okama De Souza, José Renato M. De Sousa, Gilberto Bruno Ellwanger
    Abstract:

    Abstract In subsea wells, the Surface Casing String should be fully cemented but, eventually, this is not possible due to the long length of the String and/or the soil characteristics. As the Surface and the structural Casings are the foundations of any subsea well, a partially cemented Surface Casing may allow significant wellhead movements, which affect the structural response of the well. This article, therefore, addresses the prediction of wellhead axial movements considering subsea wells where the Surface Casings are partially cemented. These movements are assessed with a multi-String model composed of nonlinear springs and bars that represent the Casing Strings. Nonlinear hysteretic t-z curves represent the soil and a developed finite element (FE), which combines these curves and the stiffness of the structural Casing String, represents this String. A typical subsea well is analyzed assuming different soil-structural Casing conditions and uncemented lengths. These analyses evidenced the significant impact of the uncemented length on the wellhead movements and on the stresses in the Casing Strings, especially if the structural Casing load capacity is overcome. Comparisons with results from an analytical and a FE model developed in a commercial software showed good agreement and highlight the need to adequately modeling the structural Casing-soil interaction.

Bernt S. Aadnøy - One of the best experts on this subject based on the ideXlab platform.

  • The Effect of a Fatigue Failure on the Wellhead Ultimate Load Capacity
    Volume 1: Offshore Technology, 2012
    Co-Authors: Lorents Reinås, Morten Sæther, Bernt S. Aadnøy
    Abstract:

    A subsea well will experience external loading during drilling operations that can lead to the development of a fatigue fracture in the primary load bearing structural members of the upper well construction. Such a fatigue fracture can occur at several fatigue hotspots which all are located in the upper part of a subsea well. There are two main load sharing structural members; the outer tubular String named the conductor (structural) Casing and the next tubular String named the Surface Casing. Both these Strings have a circumferential load bearing weld close to the top. The load sharing between these 2 tubular Strings are affected by the supported weight from further tubular Strings placed inside the well.This paper discusses the residual ultimate load capacity of a typical North Sea subsea well assuming that a fatigue fracture has developed. The discussion is based on FEM analysis results where a fully developed fatigue fracture has been introduced to the analytical model of a typical well either to the conductor part of the well or to the Surface Casing String. Then the residual ultimate load capacity is evaluated assuming a fully developed fatigue fracture. Evaluations presented herein can be important and necessary tools in considering the consequences of a possible fatigue failure of a subsea well.A reduction in ultimate load capacity due to a fatigue fracture may reduce the safety margin should an accidental or extreme loading occur. The results indicate that the location of the potential fatigue failure is important when assessing the residual ultimate load capacity. If the factored fatigue life of a subsea well is approaching its limit the presence of a fatigue fracture should be assumed. The most prudent approach would then be to perform a permanent P&A operation of the well. Planning of such operations should comprehend the possibility of reduced structural capacity of the well due to a fatigue fracture. This paper also discusses the results in an operational context. The applied methodology is outlined and illustrative results are presented from a typical North Sea well.Copyright © 2012 by ASME

R. P. Herrmann - One of the best experts on this subject based on the ideXlab platform.

  • Concentric riser will reduce mud weight margins, improve gas-handling safety
    Oil & Gas Journal, 1998
    Co-Authors: John Martin Shaughnessy, R. P. Herrmann
    Abstract:

    A high-pressure concentric riser, consisting of a Surface Casing String run within the riser, will have the potential to use a dual-density mud system to reduce mud weight margins, allowing operators to set fewer Casing Strings in deepwater environments. An additional benefit includes improved gas-handling safety above the seafloor. In comparison with the concentric riser system, conventional marine risers are not designed to contain pressure; instead, they serve primarily as a conduit between the seafloor blowout preventer (BOP) and the rig floor. The paper describes the development, configuration, and safety of the riser. To illustrate the potential benefits, an example application is described. The paper also discusses additional advantages and operational limitations.