HOUMA (AP) — Workers have started drilling a relief well to secure a gas well that blew out in the Gulf of Mexico last month off the coast of Louisiana.

The federal Bureau of Safety and Environmental Enforcement said the drilling began Sunday and is expected to take about 35 days to complete. Drilling mud and cement will be pumped into the well once the relief well intercepts it.

The bureau says a sheen can no longer be seen near the site of the blowout.

Nobody was injured when the well owned by Houston-based Walter Oil & Gas Corp. blew out on July 23. All 44 people aboard a drilling rig were evacuated before a fire broke out.

Authorities said sand and debris has clogged the well and stopped the flow of gas.