Abstract

The Liuhua 29-2 gas field is a marginal deepwater gas field in the South China Sea, which comprises 1 subsea production well, 1 subsea pipeline and 1 electrohydraulic control and chemical injection umbilical tied-back to the existing Liuhua 29-1 subsea manifold, in water depth from 681 to 753m. Several leading technologies were implemented in this project, such as highly integrated subsea PLEM, high reliable design for first deep water application of a newly developed multiphase flow meter (MPFM), light-weight mudmat and heavy PLEM J-Mode installation etc. The Liuhua 29-2 field development provides a reference project execution model for future marginal deepwater gas field development and new subsea instrument application.

Introduction

Although renewable energy is getting widely used, oil and gas still play a dominant role in global energy systems. Natural gas demand is expected to grow at an average rate of 1.5% per year from 2019 to 2025 (IEA, 2020). In order to meet the demand of the downstream consumption, it is important for a gas gathering and processing facility to have stable gas production and supply from upstream production fields. Surrounding marginal fields and prospects are potential supplements for the main developing field to keep stable gas production and supply in mid to late field life and thus to prolong the service life of the offshore infrastructure. Meanwhile, an economical solution is the key for unlock the development of a marginal gas field. Subsea tie-back to nearby existing production facilities is one of the most economical solutions for a marginal gas field. Based on this strategy, optimization of development solution will make the development more profitable.

The Liuhua 29-2 gas field is located about 15km west of the Liuhua 29-1gas field, in 753m water depth of South China Sea. Liuhua 29-2 is a typical marginal deepwater gas field developed with a single production well. The development plans to tie-back the Liuhua 29-2 gas field to the Liuhua 29-1subsea manifold located at about 681m water depth via 1 subsea pipeline and 1 umbilical. The mixed flow will be transferred to the Liwan 3-1 subsea production system (Fig.1). To make Liuhua 29-2 gas field a more profitable development, innovations in both subsea production system and facilities were successfully implemented. Other features of Liuhua 29-2 gas field development are:

• Pipeline requires intelligent pigging

• Allowing future subsea tie-in

• First application of a new developed subsea multiphase flow meter (MPFM)

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