Abstract

NOTE: No Figures Available

This paper presents the work performed by CONOCO INDONESIA and COFLEXIP to develop a method that will permit the efficient and economical recovery of hydrocarbon reserves from offshore finds which fall in the category of marginal fields, such as Conoco's Kepiting Field in 300' of water in the contract area known as Block "B" in the Natuna Sea of Indonesia.

The challenge was to find a system that would permit safe and reliable production operations from sea floor completions, and at the same time allow for well reentry by conventional wireline methods and techniques in order to service downhole safety valves, install or replace artificial lift equipment, set plugs, open/close sliding sleeves, etc.

The critical component of the system was identified as the submarine link connecting the seafloor completions to a specially designed Floating Production Storage and Offtake Barge (FPSO), which was to be located directly above the wells and moored in a spread fashion by eight anchor lines.

Two flexible pipe riser system alternatives were thoroughly analyzed; one known as "Chinese Lantern" configuration, and the other a combination of "Free Hanging" production control lines and special risers for wireline operations. The risers in a "Chinese Lantern" configuration are equipped with flotation such that the risers bow with uniform curvature throughout, thus permitting wireline tool entry. Two risers thus equipped and designed to bow in opposite directions form the shape of a paper lantern, hence the term "Chinese Lantern". "Free Hanging" risers also are equipped with flotation, however the tops of the risers have no flotation and bend over, or "free-hang" from a surface buoy. These risers must be pulled to the surface and held in tension for wireline entry.

This paper describes :

1. The predicted behavior of the "Chinese Lantern" flexible riser under various producing conditions and barge positions.

2. The proposed design and configuration of the special Wireline Riser under the "Free Hanging" riser system.

3. The proposed method of tying the Wire Line Riser into the FPSO, and provisions required to accomplish wireline work.

4. How a maximum of four seafloor completions can be connected and produced into the FPSO.

The flexible riser solution which is described in the paper is not the final solution used in the Kepiting development.