(b) Describe the principal audit work to be performed in respect of the useful lives of Shire Oil Co’s rig platforms.(6 marks)

正确答案：
(b) Principal audit work – useful life of rig platforms
Tutorial notes: The platforms are just one item of each rig. Candidates should not be awarded marks here for the matters
to be considered in the assessment of useful lives (since this is illustrated in the scenario). No marks will be awarded for
criticising management for estimating useful lives on a per platform. basis or for audit work on depreciation charges/carrying
amounts unrelated to the determination of useful lives.
■ Review of management’s annual assessment of the useful life of each rig at 31 December 2005 and corroboration of
any information that has led to a change in previous estimates. For example, for the abandoned rig, where useful life
has been assessed to be at an end, obtain:
? weather reports;
? incident report supported by photographs;
? insurance claim, etc.
■ Consider management’s past experience and expertise in estimating useful lives. For example, if all lives initially
assessed as short (c. 15 years) are subsequently lengthened (or long lives consistently shortened) this would suggest
that management is being over (under) prudent in its initial estimates.
■ Review of industry comparatives as published in the annual reports of other oil producers.
■ Comparison of actual maintenance costs against budgeted to confirm that the investment needed in maintenance, to
achieve expected life expectancy, is being made.
■ Comparison of actual output (oil extracted) against budgeted. If actual output is less than budgeted the economic life
of the platform. may be:
? shorter (e.g. because there is less oil to be extracted than originally surveyed); or
? longer (e.g. because the rate of extraction is less than budgeted).
Tutorial note: An increase in actual output can be explained conversely.
■ A review of the results of management’s impairment testing of each rig (i.e. the cash-generating unit of which each
platform. is a part).
■ Recalculations of cash flow projections (based on reasonable and supportable assumptions) discounted at a suitable
pre-tax rate.
Tutorial note: As the rigs will not have readily determinable net selling prices (each one being unique and not available
for sale) any impairment will be assessed by a comparison of value in use against carrying amount.
■ Review of working papers of geologist/quantity surveyor(s) employed by Shire supporting estimations of reserves used
in the determination of useful lives of rigs.