BHP says its production and cost guidance is unchanged for the financial year, although petroleum production is likely to be at the lower end of the range.

In a first half update, chief executive Mike Henry told the market BHP has delivered solid operational performances across the portfolio.

Petroleum production fell by nine per cent to 57 million barrels of crude oil equivalent, but guidance for the 2020 financial year remains unchanged at between 110 and 116 mboe.

BHP has six major projects under way in petroleum, copper, iron ore and potash, with a budget of $US11.4 billion.

All were tracking to plan, according to Mr Henry.