Figures for the September quarter suggest the assets that are bound to dominate the demerged entity are in good shape, with multiple production records set during the period.

The coking-coal mines in the Illawarra region posted a record production level of 2.3 million tonnes, 64 per cent better than the same period in 2013, and easily the best result for the division in any of the past five quarters.

BHP said the record had been achieved with the help of several important productivity initiatives, and came despite the Dendrobium mine being out of action.

There was good news for the new company in terms of its energy coal assets, too, despite the overall performance in energy coal being poor.

The energy coal assets in Colombia and Australia, which were dogged by floods and underperformance respectively during the period, will remain with BHP after the split, while the South African energy coal assets bound for the demerger performed much better.

Both production and sales of energy coal in South Africa were easily the best seen in the past five quarters

The Cannington silver, lead and zinc mine in Queensland was also among the stronger performers, with higher throughput at the mill ensuring the amounts of payable silver, payable zinc and payable lead produced during the quarter were much better than at any time over the past 15 months.

Pengana Capital resources fund manager Tim Schroeders said while it was only one quarter, it would make sense for BHP to have those assets performing well ahead of launching the demerger.

"I'm sure there has been a very big focus on making sure those assets are working as well as they can over the next 12 months to realise as much value as possible for Spinco," he said.

The results come ahead of several important days of spruiking the demerger in London, where BHP will hold an annual meeting of shareholders on Thursday night, and then an investor day on Monday.

But the positive trend wasn't true for all the assets that are bound for the demerger; production from most of the aluminium and alumina business was weak, while some of the Australian manganese assets couldn't match the very good workrates seen at the South African Manganese assets.

The Cerro Matoso nickel operation in Colombia performed weaker than in the September quarter of 2013, and is forecast to encounter lower grades and recoveries in the near future.

"There is only so much you can do with assets that are tired and won't lend themselves to easy gains ... with some of the assets that are looking for a new home there is very little that you can do," Mr Schroeders said.

The highlight among BHP's core assets was petroleum, which like the iron ore division, managed to perform at rates much better than guidance for the 2015 financial year would suggest.

The 67.4 million barrels of oil equivalent produced in the September quarter was 7 per cent higher than the same period last year, and well ahead of analyst estimates.

Strong production of shale liquids was behind the better-than-expected result.

The 62 million tonnes produced by BHP's Pilbara iron ore division means that business is also ahead of schedule on its promise to produce 245 million tonnes in the 2015 financial year, and a similar situation has emerged at the Queensland coking coal business, where production was 25 per cent better than the same time last year.

The outperformance prompted investors to contemplate the likelihood of guidance upgrades later this year, but Mr Schroeders said it was important for the miner to get ahead of guidance before weather started to challenge the iron ore and coking coal businesses in particular during the Australian summer.

"They try to bang out as much as they can ahead of cyclone season because they are, to a degree, at the mercy of the elements once cyclone season begins, but nonetheless it is still pleasing to see there are no hiccups in trying to achieve what are increasingly stretch targets," he said.

RBC Capital Markets said the quarter was solid overall, but the performance from the copper division - which produced 17 per cent less than the previous quarter and 13 per cent less than RBC's targets - was "weak".

Copper production was hampered by maintenance at three mines, as well as floods and strikes in Chile.

BHP shares closed 52¢ higher at $34.27.