The Role of Model Testing in the Execution of Deepwater Projects

Magee, Allan R. (National University of Singapore)

OnePetro 

Abstract

For deepwater developments involving floating platforms in harsh environmental conditions which lie beyond well-established industry practices, model tests are usually required. The paper describes the different types of model tests and their respective objectives, scopes, and requirements. Different types of testing facilities are also described. The objective is to give an overview of various aspects of model testing, so the reader will come away with a better understanding of how and why model tests are performed and how they can best be used in projects.

The timing of tests and their interaction with the project schedule is also described. For example, model tests may be carried out early in the design for concept selection studies, or sometimes at the end of FEED for a specific concept application. Project tests are often performed at the beginning of detailed engineering to resolve any outstanding design issues or sometimes near the end of the project to confirm the effects of certain changes. These different test types have different methods, requirements, procedures and results.

Model tests may address installations, operations or performance of deepwater systems such as mooring and dynamic riser interactions or may generate benchmarking data for CFD. Depending on the type of tests, certain key aspects must be carefully controlled. Required test data and the cost-benefit trade-offs of different test objectives are discussed. Results and observations are given for several model testing applications of deepwater developments in Asia Pacific region and elsewhere. Examples of different types of tests are used to draw conclusions about the role of tests.

Looking ahead to the future, several deepwater testing basins are under development in different parts of the world. Limitations such as scale effects and basin boundary truncations are discussed. Ongoing research into novel model testing methods currently being carried out and their potential to improve the accuracy and reliability of full-scale predictions are pointed out. CFD or so-called numerical wave tank is a relatively mature tool which is gaining use in offshore projects and promises to overcome some of these limitations. Fortunately, improvements in available computing power and software are continually reducing the required computation time and cost. Both physical tests and complementary CFD simulations are required to obtain a complete picture of the full-scale performance of deepwater platforms. The need for full-scale measurements and design feedback is often over-looked but benefits future projects by closing the design loop to reduce future conservatism.