Systems dynamic model of wear evolution for sheaves used in oil and gas hoisting operations

Abstract

The global offshore drilling contracted fleet consisted of 378 jack-ups, 68 semisubmersibles and 73 drillships, according to Westwood Global Energy Group, as of September 2023. In most regions of the world, rig activity has picked up from increased operator demand and pushed the marketed utilization for jack-ups from 76% to 85%, semis from 60% to 80% and drillships from 82% to 90%. The utilization of a drilling rig depends on various factors, mainly drilling demand, rig capability and specifications, and rig efficiency and reliability. Worn sheave grooves can pull down the efficiency of a drive by 8% accelerate the wearing of ropes reduce rope life, increase maintenance costs, and the need for more frequent rope replacements. Wear depth for sheaves is typically measured as the depth of wear in the groove of the sheave, which indicates the extent to which the sheave has worn down over time. Research on surface wear of wire rope caused by the contact between the wire rope and the sheave has rarely been carried out. Upgrading Archard’s Wear model is needed to provide a better estimation of wear depth for sheaves. Moreover, the wear coefficient shall be determined. Therefore, the purpose of this paper is to model the wear evolution caused by the sliding contact between the wire rope and the sheave. To achieve this purpose, case sheaves were purposefully selected, studied and modelled using both the analytical and simulation modelling approaches.