(Reuters) - Oil and gas explorer Callon Petroleum Co CPE.N has hired advisers to restructure its more than $3 billion in debt after a plunge in energy prices soured its acquisition of a rival, people familiar with the matter said on Wednesday.

Callon paid $740 million in stock to acquire Carrizo Oil & Gas Inc almost four months ago and assumed its $1.7 billion in debt obligations. While Callon’s debt does not come due until 2023, it is seeking to avoid a cash crunch amid falling revenue and dwindling financing options for energy producers.

Callon is working with debt restructuring attorneys and is also retaining the services of an investment bank, the sources said, adding that a decision on a specific course of debt restructuring was not imminent.

The sources requested anonymity because the matter is confidential. Callon did not respond to a request for comment.

An oil price war between Saudi Arabia and Russia and economic fallout from the coronavirus pandemic have sent shockwaves through the North American energy sector. Whiting Petroleum Corp WLL.N said on Wednesday it would file for Chapter 11 bankruptcy protection, the first publicly-listed U.S. producer to do so since oil prices cratered to 18 year-lows.

A number of U.S. shale firms have already hired financial and legal advisers to help tackle their debt piles, including Chesapeake Energy Corp CHK.N and Chaparral Energy Inc CHAP.N.

Callon operates in the Texas shale plays of the Permian and the Eagle Ford. To cope with the oil price downturn, Callon announced last month it would cut its 2020 capital expenditure by 25% and take its rig count to five from nine before the end of the second quarter.

Callon had $3.2 billion of long-term debt at the end of 2019 and $700 million of liquidity as of the end of February, according to regulatory filings.

The Houston-based company’s shares have lost three-quarters of their value in the last month. Its bonds due in April 2023 are trading at a massive discount of around 22.5 cents on the dollar, to offer a presumptive yield of 72.6%, according to Refinitiv Eikon data.

The acquisition of Carrizo had attracted the ire of hedge fund Paulson & Co, which argued that Callon was overpaying for Carrizo and should have put itself up for sale instead. Paulson consented to the deal after the deal price tag was revised to $740 million from $1.2 billion.