The change orders will bring the total estimated contract revenue to WorleyParsons Arabia to $US234 million ($A332 million), up from the previously flagged contract revenue of $133 million.WorleyParsons, which owns a 50% stake in WorleyParsons Arabia, will receive half of the estimated contracted revenue of $117 million, up from $67 million. The company said the change orders took place as a result of construction of the phosphate mine, chemicals complex and minesite extending for a longer period than originally estimated. Under the change order, WorleyParsons Arabia will provide additional services up until December 31 and will also provide project management services for related infrastructure as part of its contract.