Applied High Pressure Coiled Tubing Technology Solves Resin Sand Control Problems In A Gulf Of Mexico High Pressure Gas Well

Abstract

Abstract The current API and ASME design codes on wall thickness selection are too restrictive for the application of high pressure subsea flowlines. At present the codes require flowlines to be designed to wellhead shut-in pressure using Barlow design formula, which is based on first yield, and working stress safety factors established decades ago. Recent advances made in pipe manufacturing, design engineering, and the considerable plasticity of thick walled steel pipe render the current design overly conservative, resulting in severe cost penalties for long distance subsea tiebacks. The current work describes the application of Burst Limit State Design principles to the design of subsea tiebacks. The paper discusses the limitations of the classical approach and quantifies the uncertainties, risks, and economics of limit state design, based on results obtained from burst pressure test data obtained from various industry sources. It is expected that this work will lead to a review of the existing codes by the regulatory bodies and the recommendation to change current in design practices. The work will enable deepwater subsea tiebacks to be designed in accordance with limit state principles and safety factors reflecting the current state-of-the-art technology of pipe materials, manufacture, welding, quality control and pipeline design. This will lead to the optimum design of subsea flowlines. This work is mainly directed towards the large D/T ratios required for high pressure subsea flowlines, and is different from the low D/T ratio work carried out by SUPERB and IS0 working committees in Europe. However, it is intended that this work will complement the work carried out elsewhere, leading to a consistent application of burst pressure design to pipelines and flowlines. Introduction DeepStar 3300 Committee commissioned a study to evaluate the feasibility of using the Burst Limit State criteria to design subsea flowlines. The work consisted of:Collection of data from published sources and DeepStar members.Identification of Limit State Design models for Burst Assessment of code compliancePreparation of submissions to API and ASME for code changes The work presented here is limited to the Phase 1 of the study, and includes a description of the data collected, and the preliminary Limit State Design philosophy under development. Comparative cost data for current design practices, and Limit State Design also given to establish the potential cost savings of using Limit State Design. Recognition of the uncertainties associated with engineering systems has led to the wide application of the concept of reliability as a basis for structural design. This is evidenced by the move in Europe and North America to develop limit states codes for pipeline design.