HIPPS Concepts for a Subsea Field Scenario

Abstract

Abstract This paper is based on afeasibility study investigating the possibilities ofusing a HIPPS (High Integrity Pressure Protection System) to protect a subsea pipeline which is not rated for full wellhead shut-in pressure. Several different HIPPS configurations have been evaluated with respect to safety, production regularity and various qualitative criteria for use in a specific subsea field scenario containing six wells. A preliminary review ofthe feasibility ofcurrent technology for HIPPS applications has been made. The conclusion is that a subsea HIPPS can be designed with satisfactory safety performance based on current technology. Thepaper also covers requirements posed to the HIPPS equipment as well as general requirements for process design and operation when a pipeline not ratedforfull well shut-in pressure is present. 1 Introduction The feasibility study on which this paper is based, was performed by SINTEF, Norway in 1993 - 1994, called "Subsea OPPS Feasibility Study". The objective of the study was to describe the state-of-the-art solutions for pipeline overpressureprotection systems. The study has been made on a specific field scenario reviewed in Chapter 2. Many of the results and the aspects addressed are however generally applicable to any subsea field scenario where the purpose is to investigate the possibilities of applying a HIPPS, see also Chapter 8. The presence of a pipeline not rated for full well shut-in pressure (in the following called low pressure pipeline) imposes requirements in the process design outside the HIPPS as well as in process operation, see Chapter 3. A brief review of the technology included in a HIPPS is given in Chapter 4. In Chapter 5 some alternative HIPPS configurations for this field scenario are presented. The safety and production regularity analysis for these configurations is reviewed in Chapter 6, and a qualitative evaluation is madein Chapter 7. Nomenclature and references are given at the end of the paper. 2 Field Scenario Review The study was based on a field scenario containing 6 wells in one template. Studies were made for one gas/condensate field and one oil field. The oil field imposes stricter requirements to the response time of the HIPPS system due to fasterpressure buildup (lower compressibility). The main field parameters are summarized in figure Figure 2.1. Complete field data is not included in this paper. Figure 2.1 Field layout. (Available In Full Paper) 3 Requirements to HIPPS design The presence of a low pressure pipeline imposes requirements to:Process designProcess operationAHIPPS system Even if the two first points are not the main topics of this paper, it is very important to keep in mind that the presence ofa low pressure pipeline creates challenges that can not be solved by introducing the HIPPS system only. The main requirements to process design and process operation are therefore given in the following. Process Design and Operation Requirements In a system with a low pressure pipeline protected by a HIPPS system the following process design and operation requirements apply: