Astron reported a memorial service would take place at the Astron Energy Milnerton refinery this week.
On the physical impact of the explosion, the company said there was "no threat to fuel supplies because of this incident".
"A post-incident risk assessment has been conducted and there is no health risk to the communities surrounding the refinery. The overall plant remains stable. The affected area is barricaded and we continue to have support from the local authorities."
And on the origin of the blast, the company reported: "Astron Energy is committed to a full investigation of the incident, in co-operation with all the relevant authorities, to learn the cause and to take steps to prevent any re-occurrence of this tragic event."