Weatherford International Ltd. WFT, -0.33% on Friday said it expects to file for chapter 11 bankruptcy protection, citing industry conditions as well as company-specific issues.

The oil-field service company expects to reach an agreement in principle with noteholders on a restructuring support agreement.

First-quarter results were hurt by weak sector conditions "in North America, primarily in Canada, combined with seasonal and weather-related disruptions in the United States, Europe and Russia as well as project start-up costs and an unfavorable impact from foreign exchange in Argentina."

Shares fell 67% to 12 cents after hours.

Write to Josh Beckerman at josh.beckerman@wsj.com

Weatherford International Ltd. WFT said it expects to file for chapter 11 bankruptcy protection, citing industry conditions and company-specific issues.

The oil-field service company expects to reach an agreement in principle with noteholders on a restructuring support agreement that would reduce debt by about $5.85 billion.

Under the plan, existing unsecured notes would be exchanged for 99% of the reorganized company's stock, plus new unsecured notes.

Weatherford said it has been hurt by sector conditions in North America, primarily Canada, and "seasonal and weather-related disruptions in the United States, Europe and Russia as well as project start-up costs and an unfavorable impact from foreign exchange in Argentina."

Shares fell 70% to 11 cents in after-hours trading on Friday.

Weatherford said its first-quarter net loss was $481 million, or 48 cents a share, compared with a loss of $245 million, or 25 cents a share, a year earlier. Revenue fell to $1.35 billion from $1.42 billion.

Weatherford said "the uncertainty of anticipated activity," including lower spending by many customers, has affected working capital, retention of key personnel and access to debt and equity at suitable terms.

On Feb. 1, Weatherford reported a $2.1 billion fourth-quarter net loss reflecting a goodwill write-off but said it posted positive operating cash flow and was making progress on its transformation plans.

As of late April, the Baar, Switzerland-based company operated in more than 80 countries and had about 26,500 employees.

Write to Josh Beckerman at josh.beckerman@wsj.com