VIV Predictions for an SCR in Sheared Ocean Currents

Vortex Induced Vibration (VIV) prediction is one of the key areas of interest in Deepwater Riser Engineering. Several Joint Industry Projects (JIPs) are currently in progress in this field, which results in an increase of experimental data available to design engineers, in revisions of specialized software and in development of new engineering tools. This paper presents VIV predictions for a hypothetical Steel Catenary Riser (SCR) using the latest versions of the SHEAR7 and the VIVA/VIVARRAY Programs. Both built-in and extended program capabilities are utilized and detailed plots of computation results are presented. Sensitivity studies on the influence of variations of selected design parameters are also included in the paper. Finite Element Analyses (FEAs) results and simple engineering tools were utilized in parallel to built-in program features. The calculations demonstrated, that for the riser investigated and presumably also for a wide variety of similar SCRs, that the built in program features are sufficient to predict VIVs conservatively. Notes on VIV predictions in a real ocean and on selected areas that require investigation are also included.

Unified Model for Gas-Liquid Pipe Flow Via Slug Dynamics: Part 1 — Model Development

A unified hydrodynamic model is developed for predictions of flow pattern transitions, pressure gradient, liquid holdup and slug characteristics in gas-liquid pipe flow at different inclination angles from −90 to 90 deg. The model is based on the dynamics of slug flow, which shares transition boundaries with all the other flow patterns. By use of the entire film zone as the control volume, the momentum exchange between the slug body and the film zone is introduced into the momentum equations for slug flow. The equations of slug flow are used not only to calculate the slug characteristics, but also to predict transitions from slug flow to other flow patterns. Significant effort has been made to eliminate discontinuities among the closure relationships through careful selection and generalization. The flow pattern classification is also simplified according to the hydrodynamic characteristics of two-phase flow.

Stress Analysis of Composite Tubes Under Tensile Fatigue Loading in a Simulated Seawater Environment

It is the purpose of this study to investigate the effects of fatigue loading on two variations of hybrid composite tubes. The two types of samples are both composed of AS-4D/carbon fibers and e-glass fibers. The key distinctions between the two samples being the orientation and the number of layers. The samples were composed of the following orientations [90/20/90/20/90/20/20/90/20] and [90/90/20/90/20/20/90/20]. The experiment is designed to not only compare the two samples, but to develop some experimental data for a fatigue curve for similar materials. All loading for this experiment takes place in a controlled environment. Both temperature and the specific gravity of the water are measured and controlled.

New Micromechanics Formulations for the Assessment of Elastic Moduli of Granular Assemblies

The elastic moduli of granular assemblies are sensitive to the confining conditions as well as the volume fractions of each of its constituents (i.e. solid, fluid, gas). Theoretical estimations using granular mechanics are based on assumed distributions of contact normals and branch vectors using idealized particle shapes and therefore cannot quantitatively predict the moduli. This paper presents a new method to use the moduli of the granular skeleton and those of the matrix to estimate the moduli of the composite and makes it possible to back-calculate the moduli of the skeleton from the moduli of the composite and the matrix.

Recent Advances in Barite Sag Technology

The occurrence of barite sag is a well recognized but poorly understood phenomenon in the drilling industry. Industry experts have offered a variety of measuring parameters, based upon empirical data, that only partially correlate with the occurrence of barite sag. The industry’s lack of understanding of the mechanisms and types of barite sag generally result in a poor correlation between laboratory results and field observations of barite sag. The financial impact of barite sag on drilling costs, usually resulting from rig-time lost while circulating and conditioning the mud system, is not trivial. There are reported incidences where recurring barite sag problems have resulted in the loss of drilling projects. The accuracy and relevance of technology utilized to manage barite sag can help reduce drilling costs. In the field barite sag frequently occurs in deviated wells where pipe eccentricity creates conditions conducive to dynamic sag. With the exception of a flow loop, laboratory tests do not simulate field conditions. Historically, laboratory tests characterize density variations arising from a vertical fluid column as static or dynamic sag without proper consideration to angle, pipe eccentricity, annular shear rates and annular flow. This paper reviews traditional and newly-emerging barite sag technology and compares their ability to predict barite sag potential. This potential will be determined under dynamic and static conditions in a sophisticated flow loop configured to match certain field conditions.

Protecting Proprietary Software in the Petroleum Industry

The development, management, and exploitation of Intellectual Property is critical to the health and prosperity of the Petroleum Industry. This paper provides a summary of how Petroleum companies can protect their proprietary software. Specifically, this paper will address the risks and benefits associated with protecting proprietary software through copyrights, patents, or trade secrets. With this background, the paper will address how Petroleum Companies can optimally develop, manage, and exploit their Intellectual Property to maximize industry production, efficiency, and profitability.

An Improved Approach to the Semi-Process-Oriented Implementation of Standardised ERP-Systems

The improved approach is considered as a life-cycle model that combines the necessities of process improvement projects and the implementation of modern integrated Standard Software systems. To improve the company’s business processes by means of the Standard Software implementation, each phase of the entire implementation life cycle puts its focus on optimising the customer’s underlying business processes. In addition, to intensify the benefits resulting from the process-oriented system implementation, the presented approach is extended by a certain guidance to organise a process-driven project team.

Using Torsion Bar Testing to Determine Fracture Toughness of Ceramic Materials

A new method, designated as Spiral Notch Torsion Test (SNoTT), is introduced for determining fracture toughness KIC of materials ranging from metallic alloys to brittle ceramics and their composites. A round-rod specimen having a V-grooved spiral line with a 45° pitch is subjected to pure torsion. This loading configuration creates a uniform tensile-stress crack-opening mode, Mode-I, with a transverse plane-strain state along the grooved line. This technique is analogous to the conventional test method using a compact-type specimen with a thickness equivalent to the full length of the spiral line. KIC values are determined from the fracture load and crack length with the aid of an in-house developed 3-D finite element program (TOR3D-KIC). A mixed mode (modes I and III) fracture toughness value can be determined by varying the pitch of the spiral line or varying the ratio of axial to torsion loads. Since the key information needed for determining KIC values is manifested within a small region near the crack tip, the specimen can be significantly miniaturized without the loss of generality. Limited results obtained for various materials are compared with published KIC values, showing differences of less than 2% in general and 6% maximum in one case. The experimental technique and theoretical basis of the proposed method are presented in detail.

Investigation of the Manufacturability of Smart Composite Piping Structures Using Life Cycle Cost Modeling and Uncertainty Analysis

FRP composites are finding increasing use in the civilian applications such as highways, bridges, pipes etc. This analysis focuses on the FRP piping systems used in the Petrochemical industries under extreme conditions. Due to the high operational and maintenance costs involved with pipes made from traditional materials, there is a need to develop a smart inspection system that replaces or eliminates the traditional inspection and maintenance techniques, providing continuous and reliable monitoring of the structure. Smart FRP pipes have an embedded smart sensor system incorporated in them, providing continuous and reliable monitoring of the pipe structure. This helps in preventing catastrophic failure of pipes thereby reducing the costs involved with the pipe failure. Smart FRP systems have a very high initial investment cost, and therefore a cost comparison model is needed in order to justify their use against traditionally used materials. A Life Cycle Cost (LCC) comparison model has been developed in this paper, which shows that despite high initial investment costs, large savings could be made in the operational and maintenance costs with the use of Smart FRP pipes. This cost model Calculates the life cycle costs of Steel, FRP and Smart FRP pipes, and determines the alternative with the lowest life cycle cost. To deal with an uncertainty associated with the cost factors, used in calculating the LCC of the three alternatives, an uncertainty analysis has been performed. An computer spreadsheet has been programmed in order to perform the LCC and Uncertainty Analysis. This analysis has laid down the basic foundations for a larger cost model, wherein; several other alternatives materials and factors could be included. This would further help in widening the scope of use of Smart Structures in various industries. Certain aspects of the data used in this analysis may be disputable, however for the purpose of modeling and procedural demonstration, the gathered and available information was used to perform our analysis. Therefore, use of this data outside of the scope and context of this report is not warranted.

Numerical Simulation of Combustion in a Cylindrical Porous Medium

Convectional free flame combustion causes the temperature rise in the vicinity of the flame to be very steep, resulting in high temperatures, consequently NOx formation enhances. The fact is that the thermal conductivity of gases are very low, i.e., poor thermal conductors. Combustion in porous media elevates this problem by enhancing heat conduction and thermal radiation from the flame zone, which reduces the flame temperature and NOx formation. Also, heat transfer from the free flame to a load is mainly by convection, while heat transfer is by convection and radiation from combustion zone in porous medium to a load. Moreover, it is easy to stabilize the flame in a porous medium, where the thermophysical properties of the porous medium can engineered for specific application. Most of the work is done on flat type porous burner, where the axial flow of gaseous fuel air mixture forces through a layer of porous medium. In this report a concept of cylindrical porous burner is introduced, where the fuel air mixture is forced to flow radially. Mathematical models and simulation results are introduced for both burners, axial and radial flow burners. Preliminary results of the comparison between the thermal performances between the mentioned burners are discussed. The results revealed that the cylindrical burner has superiority over the convectional flat burner. The cylindrical burner has a wide range stability limits and may produce less NOx than the flat type burners.