THE STRUCTURAL INTEGRITY MONITORING OF GROUT/STEEL ANNULI ON OFFSHORE INSTALLATIONS SUBSEA

Cel

To develop a non-destructive measurement and analysis technique and associated instrumentation to assess the integrity of the grouted annular connections between the piles and legs of offshore jackets.
The proposed technique will use impulse excitation and dynamic response measurements to detect the presence of voids in the grout.
The technique will be developed into a product suitable for application by divers, with associated instrumentation to provide on-site assessments of grout integrity.
The results obtained in Phase 2 were found to be of a low repeatability and were often corrupted with background noise. This subsequently hampered the data analysis and created problems determining any trends that may have been incorporated in the PASS/FAIL algorithm. By changing the method of the data acquisition from a manually controlled system to a semi-automated digital system the quality of results was improved sufficiently to enable developemnt of a PASS/FAIL algorithm for the final system.
The performance of the final system was not as good as desired, despite many improvements being made in the PASS/FAIL algorithm. By altering the method of weighting the monitored parameters and also eliminating some parameters which did not prove to be a good indicator for a void or grout, the system could determine a difference between void and grout in some of the tests.
The results did show that in some cases the impulse response technique could detect voids in grouted pile/sleeve members, but with a limited resolution. It must also be taken into account that all the tests were carried under ideal conditions and the probability of testing under such conditions in the field were remote. Therefore, the conclusion arrived at was that the system could not perform with sufficient resolution to produce a final workable system that could operate in the field, consequently the following phases 4 and 5 of the project were abandoned.
The project will be carried out in 5 phases as follows:
Phase 1: Development of a test facility
Design and manufacture of a test facility, and procurement of tubular test specimens representing a range of skirt piled structures.
Manufacture of a pre-prototype instrumented hammer to be used in phase 2 to determine the required parameters of the subsea hammer and instrumentation.
Phase 2: Determination of Dynamic Behaviour of Preliminary Test Specimens
Test to investigate the dynamic response of tubular test specimens due to impulse excitation for: un-grouted, halfgrouted and grouted with void formers present. The specimens will model a range of void sizes to enable the limiting resolution of the technique to be quantified.
Phase 3: Development of Grout-Void Monitoring Techniaues
Further development of a data acquisition and signal processing system. Development of computer software with a pass, fail criteria for grout and voids respectively.
Phase 4: Offshore trials
Subject to theco-operation of the UK Oil and Gas Industries, a prototype system will be tested on an offshore jacket under realistic operating conditions.
Phase 5: Product development
Based on the results of the laboratory and offshore trials, further develop the technique into a product to provide on site assessments of grout integrity monitoring to be made offshore using inspection divers.

Program(-y)

ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989

Temat(-y)

1.9 - PRODUCTION SYSTEMS

Zaproszenie do składania wniosków

Data not available

System finansowania

DEM - Demonstration contracts

Koordynator

AV TECHNOLOGY LIMITED

Wkład UE

Brak danych

Adres

AVTECH HOUSE BIRDHALL LANE CHEADLE HEATH
SK3 0XU STOCKPORT
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