Still, the results topped Wall Street estimates for the period and Occidental's operating cash flow rebounded from last quarter to $2.96 billion, up 7% from the same quarter a year ago. Investors closely watch operating cash flow as a sign of a company's ability to cover shareholder payouts and operating expenses.

Core income fell to $729 million, or 97 cents per share, in the second quarter, from $848 million, or $1.10 per share, a year earlier. Analysts were expecting the company to report earnings of 93 cents a share on the same basis, according to IBES data from Refinitiv. (http://bit.ly/32VraOa)

Among its major businesses, operating profit in oil and gas fell 7% to $726 million, chemicals fell 34% to $208 million and earnings from its pipeline unit rose 32% to $331 million, compared with year-ago figures.

Profits were hurt by $107 million in one-time costs, including Anadarko-related transaction and debt financing fees.

Daily average oil and gas production was 741,000 barrels per day (bpd), up from 639,000 bpd a year earlier. Higher production was offset by weaker prices, with the realized price for its oil and U.S. natural gas off 6.7% and 85%, respectively, from a year earlier.

The company plans to hold a conference call with analysts on Thursday to discuss the results.

Icahn this month launched a campaign to unseat four Occidental directors, arguing they entered into the deal for Anadarko to preclude Occidental from becoming a takeover target. He has attacked the deal as too pricy and for the lack of an Occidental shareholder vote.

The company also said it has formed a drilling partnership with Colombia's state-run oil company Ecopetrol SA to develop its acreage in the Midland portion of the Permian shale field for up to $1.5 billion. Occidental said the agreement, which it expects to conclude in late 2019, would allow it to accelerate development plans.

Ecopetrol said the joint venture would add some 160 million barrels of crude to its proven reserves, an about 10% increase on last year's figure. It also will allow the Colombian company to gradually increase its net production to 95,000 bpd in 2027, it added.

In its last earnings report before shareholders vote on the sale on Aug. 8, Anadarko also beat analysts' estimates for quarterly profit as higher production offset lower prices for its oil.

(Reporting by Arathy S Nair in Bengaluru, Gary McWilliams in Houston and Julia Symmes Cobb in Bogota; editing by Shinjini Ganguli and G Crosse)