West Seno Field Production, Utilities and Export Facilities
Authors: Landeck Christopher R. , Pasma William D. 
Published: October 2008

Abstract
The paper describes design and startup of the production facilities, utility systems and product export infrastructure associated with the W. Seno Phase 1 development, offshore Indonesia. The facilities are located on a TLP, a Floating Production Unit (FPU) and in an onshore terminal.
The field is in approximately 3200 ft water and is located 25 miles offshore of a number of shallow water fields which Unocal has operated since the early 1970's.
This field was the first deepwater development for Unocal and for the country of Indonesia. An effort was made to design facilities which would minimize the learning curve for a long established operating group.
This paper presents a case history of the W. Seno field from a production facility design, fabrication and operations point of view. It describes many of the things employed to overcome challenges associated with differences between shallow and deep water production operations which may be applicable to other projects.

Introduction

Existing Infrastructure and Production History
Unocal signed its first Production Sharing Contract (PSC) for an operating area offshore the province of East Kalimantan (Borneo) 1960's. Production from from a number of shallow (15 ft - 330 ft wd) water oil fields has been realized since the early 1970.
The typical operation is characterized by small wellhead platforms supporting high well counts and two phase separation delivering gross liquid and gas streams to a central processing/compression platform.
Some water is treated and discharged offshore with final processing and delivery of oil and gas streams to their respective sales points occurring downstream of an onshore terminal.
Drilling requirements are met by relatively small, highly mobile, tender assisted platform supported drilling rigs.
Well completion requirements make frequent intervention necessary and workovers are performed with drilling rig, coiled tubing unit, wireline and snubbing units.

W. Seno Field Discovery and Delineation
The W. Seno Field was discovered in 1998. It is located approximately 60 km offshore in 3200 ft water. The field is 25 miles from the nearest shelf production. Figure 1 is a map of the operating area.
Figure 1 (Available in full paper)

Production Profile and Fluid Properties
Fluid characteristics obtained from wireline and DST tests were very similar to those typically observed on the shelf. Each well contains multiple stacked pay zones which will require similar workover intensive operations during the life of the field.
Planning for the development assumed that facilities and operations would be similar to those employed in shelf operations since the early 1970's.
The design field production profile is 60,000 BOPD, 150 MMSCF/D and 40,000 BWPD. Figure 2 is a graphical illustration of the design production profile for the field.
Figure 2 (Available in full paper)

System Design Criteria - Project Definition Phase
To reach full production from the field it was decided during the early stages of engineering that the field would be developed utilizing a phased approach comprising two Tension Leg Platforms (TLP's) and a Floating Production Unit (FPU).