Occidental completes $12 billion acquisition of CrownRock

International energy major Occidental Petroleum announced late on Thursday that it had closed its acquisition of CrownRock, L.P, completing a cash-and-stock deal valued at $12 billion that it had announced in December.

The announcement came after Occidental said that Colombia’s Ecopetrol would not buy a stake in the shale oil producer. State-owned Ecopetrol was in talks to possibly buy a 30% stake in CrownRock, in a transaction potentially worth $3.6 billion, Occidental said last month in a regulatory filing.

The CrownRock acquisition includes the addition of debt onto the balance sheet of Occidental, which had $18 billion in debt at the end of the first quarter. The company had said in May that it plans to sell between $4.5 billion - $6 billion of assets within 18 months of closing the CrownRock purchase, according to Reuters. The company had received a second request about the deal from the US Federal Trade Commission earlier this year, the agency said.

“By completing this transaction, Occidental adds assets that we believe make the best portfolio in our company’s history even stronger and more differentiated,” Vicki Hollub, President and Chief Executive Officer of Occidental, said in a statement.

“We also welcome new team members who will combine with ours to form a high-performing employee base that is focused on safely and efficiently developing low-emission, low-cost energy,” she added.

As one of the largest oil and gas producers in the US, Occidental’s  portfolio includes the Permian and DJ basins, and offshore Gulf of Mexico, while its chemical subsidiary OxyChem manufactures the building blocks for life-enhancing products.