Abstract

Liuhua29-1 gas field is a 7-well deepwater gas field, developed via subsea tie-back to the existing LH34-2 and LW3-1 subsea production system. Several challenges were encountered during the execution of this project, such as deep water, extreme seabed topography, solition current and very soft seabed etc. Various measures were taken to solve those difficulties, and several leading technologies were used in this project. Although affected by coronavirus pandemic, the Liuhua29-1 project achieved mechanical completion 24 days ahead of schedule and produced first gas as planned, with overall effective control on schedule, cost, safety and quality. The Liuhua29-1 field development is the first 1000m depth-level project executed by COOEC as the EPCI contractor. This paper provides valuable information and experiences of the execution of this project.

Introduction

The LW3-1 and LH34-2 gas fields were developed by China National Offshore Oil Corporation (CNOOC) and Husky Oil China Limited (HOCL) with first gas achieved in 2014. The development consists of subsea wells tied back to the fixed LW central processing platform (CEP) on the continental shelf for basic processing and compression required to deliver the fluids through a long-distance pipeline to the Gaolan onshore plant (Triolo, Mosness, Jennings, and Rezende, 2013). LW CEP is a 3-deck central processing platform with the function of liquid / gas separation, natural gas dehydration, gas compression, condensate processing, MEG and TEG regeneration. The gas processing capacity of LW CEP is 120×108 Sm3/a and MEG regeneration capacity is 67.5m3/h. The onshore facilities will further separate the fluids and prepare gas, condensate and other liquid products for delivery to the market.

The Liuhua29-1 gas field is located approximately 86 km northeast LW3-1 gas field in water depth ranging from 520 to 1150m. There are totally seven subsea wells in the Liuhua29-1 development. The LH29-1 production will be gathered at a single header manifold from seven wells: five wells adjacent to the manifold and two spur wells one at 1.6km and another 3.3km distance from the manifold. The LH29-1 production will be tied back to the LH 34-2 satellite facility with an approximately 27.1km long 12" pipeline. Production from LH 29-1 will then co-mingle with the LH 34-2 production and flow into the LW 3-1 system (Fig.1). The control and chemical system of Liuhua29-1 subsea production system utilizes the spare capacity of LW CEP. This paper introduces the technology developed and successfully implemented in Liuhua29-1 field development.

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