This paper presents and analyzes equipment development and testing, completion procedures, and maintenance operations using through-flowline (TFL) methods on five subsea wells in 100 to 200 ft (30.5 to 61 m) of water offshore Brunei. These wells, installed in 1974-76, presently are operated by Brunei Shell Petroleum and include both single-and dual-string (multizone) completions. Introduction In the early 1970's, Shell Internationale Petroleum Mij. (SIPM) undertook a series of studies aimed at the development of systems for producing deepwater oilfields beyond the continental shelf. An important building block in deepwater production systems would be the underwater completed (UWC) well. A principal objective was that the UWC wells would be drilled, completed, produced, and serviced using remote control and servicing techniques. Downhole servicing of the well would be done by pumpdown TFL techniques. Single-Zone Well In 1971 it was envisaged that the UWC wells would have to be large producers for an economical deepwater field development. The terms of reference established for a diverless deepwater subsea completion resulted in these basic requirements and assumptions:the well must be a prolific producer of 5,000 to 10,000 B/D (794.9 to 1589.8 m3/d);no artificial lift by gas lift would be needed;sand production would not be present;completion would be as simple as possible, preferably with a single production string probably 4 1/2 in. (114.3 mm) OD; androutine well servicing by TFL. It was decided to install a pilot UWC (Fairley 16) offshore Brunei (Borneo) in relatively shallow water, permitting easy intervention by divers if necessary. For this purpose a project team was set up in Brunei. Since at that time TFL tools and ancillary equipment had been well-developed only for 2 3/8-in. (60.3-mm) tubing, SIPM approached Otis Engineering Corp. in Oct. 1971 to set up a program for developing and testing TFL capability in the larger tubing size [4-in. (102-mm) nominal size tools].Subsequently Otis designed and constructed the TFL tool string and service tools, a surface-controlled subsurface safety valve suitable for TFL, a Sliding Side-Door (SSD), and a standing valve. The equipment was tested in the Otis test well in Dallas from Aug. to Oct. 1972. A number of modifications were made to the equipment. It became apparent that the "reach rod" approach using conventional sucker rods led to unacceptable friction resistance in the TFL loops. ("Reach rod" refers to an operation whereby a flow control may be installed in a nipple below the TFL circulation point by using rods or bars to span the distance between the flow control running tool and the TFL piston units, which must remain above the circulating point.) To counter this friction, knuckled spacer bars approximately 3 ft (1 m) long were introduced and later tested successfully. JPT P. 1538＾

This paper outlines the overall project for development and installation of a low profile caisson-. installed subsea Xmas tree.Following various design studies and laboratory and field testing of key components, a system for installation inside a 30 inch conductor was ordered in July 1978 from Cameron rron Works Inc. The system is designed to have all critical pressure containing components sub mudline and with the reduced profile (height) above seabed, provides for improved safety of satellite underwater wells from damage By anchors, trawl boards and even icebergs.In addition to the innovative nature of the tree design the completion includes improved 3.1/2 inch through flowline (TFL) pump down completion equipment with deep set safety valves and a dual detachable packer head for simplified workover capability. The all hydraulic control system incorporates a new design of sequencing valve for Both Xmas tree control and remote flowline connection.A semi-submersible drilling rig was used to initiate the first end flowline connection at the wellhead for suBsequent tie-in to the prelaid, surface towed, all welded subsea pipeline bundle.The Acceptance stack-up tests in the U.S.A and the subsequent Landtesting in Brunei are also described in the paper.

This paper outlines the overall project for development and installation of a low-profile, caisson-installed subsea Christmas tree.After various design studies and laboratory and field tests of key components, a system for installation inside a 30-in. conductor was ordered in July 1978 from Cameron Iron Works Inc. The system is designed to have all critical-pressure-containing components below the mudline and, with the reduced profile (height) above seabed, provides for improved safety of satellite underwater wells from damage by anchors, trawl boards, and even icebergs.In addition to the innovative nature of the tree design, the completion includes improved 31f2-in. through flowline (TFL) pumpdown completion equipment with deep set safety valves and a dual detachable packer head for simplified workover capability: The all-hydraulic control system incorporates a new design of sequencing valve for both Christmas tree control and remote flowline connection.A semi submersible drilling rig was used to initiate the first end flowline connection at the wellhead for subsequent tie-in to the prelaid, surface-towed, all-welded subsea pipeline bundle.The acceptance stack-up tests in the U.S. and the subsequent land tests in Brunei also are described in this paper.

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A new safety valve was requi red by North Sea Operators for-their prospective sub-sea completions.~he valve would have to combIne compatibility with low~ressur~s~b~sea wellhead controls with hIgh relIabIlIty. ----Fall of 1980.This paper discusses the design parameters and features of the safety system as well as the. perfor!Uance of the system in tests and In servIce.