Deepwater

The technical challenge associated with building a deepwater pipeline is often measured by the combination of pipe diameter and water depth. In the past, projects like the Blue Stream Pipeline (24 inch diameter and 2,150 m depth) and Mardi Gras Pipeline (28 inch diameter and 2,200 m depth) set the frontier for such a challenge. However, recently proposed projects, such as the South Stream Pipeline (32 inch diameter and 2,200 m depth) are setting new records.

Abstract

The Mardi Gras Transportation System is an ultra deepwater pipeline system that will support a number of prospects in the Gulf of Mexico, including the Holstein, Mad Dog, Atlantis and Thunder Horse field developments. To support the design of the deepest portions of the Mardi Gras Transportation System, a full-scale collapse test program was performed, and was aimed at measuring, quantifying and documenting the increase in pipe strength and collapse resistance as a result of the...

Abstract

With the increasing development of oil and gas reserves in water depths greater than 1500 m, linepipe used for deepwater and ultra-deepwater applications will require enhanced resistance to hydrostatic collapse. To support this need, Corus Tubes has been investigating methods by which increases in UOE linepipe collapse strength can be achieved. In particular, it has been theorised that modifications to the UOE manufacturing process can provide the necessary collapse strength...

Abstract

It has been demonstrated in previous work that, for deepwater applications, the cold forming process involved in UOE pipe manufacturing significantly reduces pipe collapse strength. To improve the understanding of these effects, Tenaris has embarked on a program to model the stages of the UOE manufacturing process using finite element methods. Previous phases of this work formulated the basis for model development and described the 2D approach taken to model the various stages of...

Abstract

The UOE-SAWL pipe manufacturing process introduces considerable plastic deformations and residual stresses to feedstock plate material. Previous experimental and analytical studies have demonstrated that the effects of this process, predominantly in its final expansion stage, significantly reduce the collapse resistance of deepwater linepipe. Finite element analyses, sensitivity analyses and full-scale tests were conducted by Tenaris and C-FER Technologies (C-FER) over the last...

Abstract

The local buckling of pipelines under external pressure is comprehensively addressed in section 5 of DNV-OS-F101 Rules for Submarine Pipeline Systems. The equations used, calculate the plastic and elastic components to give an overall collapse pressure. These equations include factors that are controlled by the pipe manufacturer. A key feature of the collapse design formula is that the compressive yield stress of UOE pipes is de-rated by 15 per cent through the use of a fabrication...

Abstract

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines. Since oil discoveries are moving towards ultra-deepwater areas, such as Pre-Salt in Brazil, collapse resistance is a key factor in the design of the pipelines.

It is known that the cold forming, and the final expansion in the UOE linepipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication...

Abstract

In many deepwater pipeline applications, a clear understanding of pipe local buckling behaviour due to excessive bending and/or external pressure is required to adequately design subsea pipeline systems to an acceptable degree of risk. With ultra-deepwater pipelines being considered for water depths of nearly 3000 m, pipe collapse, in many instances, will govern design. For example, bending loads imposed on the pipeline near the seabed (sagbend region) during installation will...

Abstract

Energy consumption outlook shows that the demand for Oil and Gas is increasing worldwide and since most of the undemanding reserves are already being explored, new reserves means longer distances from the shore and increasing water depths, of up to 3,000 meters. Collapse resistance has become a key factor in the design of pipelines for ultra-deepwater applications. UOE process is commonly used for manufacturing pipelines of large diameter and the cold work involved in this forming...

Abstract

This paper is based on some of the findings resulting from the PRCI project NDE-4E which examined the performance of various crack ILI technologies based on an industry data mining exercise. One of the project deliverables was an extensive database of crack in-line inspection (ILI) and excavation information collected from operators. This was used to characterize the field performance of ILI technologies with respect to detection, identification and sizing of crack features.

Thousan...