US 4,351,027 AGranted

Adaptive riser angle position reference system

AssigneeHoneywell Inc.

InventorsTom A. Gay, Gary L. Hartman, Gunter Stein

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Abstract

An adaptive riser angle position reference system and method for determining the horizontal position of a marine vessel relative to an underwater wellhead from angular deviations from vertical of a riser between the vessel and the wellhead are disclosed. The system comprises sensors for determining deviation from vertical of the riser at positions proximate the wellhead and the vessel and a compensation filter for adaptively filtering signals indicative of the lower and upper riser angles in accordance with filter coefficients which are determined by riser parameters. The filter coefficients are established by riser parameter identification means which effectively compares riser response, as indicated by the lower and upper riser angles, with the responses of a plurality of riser models, and selects filter coefficients corresponding to the most accurate model.

Claims15

Dependent claims

An adaptive riser angle position reference system for determining the horizontal position of a marine vessel supporting a riser which extends between the vessel and a subsea wellhead, comprising:

a first vertical angle sensor for producing a lower angle signal indicative of deviation from vertical of the lower riser at a point proximate the wellhead;
a second vertical angle sensor for producing an upper angle signal indicative of deviation from vertical of the upper riser at a point proximate the marine vessel;
compensation filter means having filter characteristics which are variable in accordance with filter coefficients supplied thereto;
riser parameter identification means connected to receive the lower and upper angle signals and operable to determine a riser model whose response approximates that of the riser and to supply corresponding filter coefficients to said compensation filter means;
first transfer means for receiving the lower and upper angle signals and supplying corresponding signals to said compensation filter means, whereby the output of said compensation filter means is indicative of vessel position;
utilization means;
and
second transfer means for receiving the output of said compensation filter means and supplying corresponding position information to said utilization means, whereby said utilization means is operable to indicate horizontal vessel position relative to the wellhead.

5 more elements

Dependencies are inferred from the claim text.