Hydrocarbon recovery process

Claim 1

A process for recovering hydrocarbons from an underground formation penetrated by an injection well and a production well which comprises: (a) injecting steam via an injection well into the formation thereby heating the formation to an elevated temperature; (b) terminating the injection of steam; (c) injecting a mixture of carbon monoxide and hydrogen via the injection well into the formation where reaction of steam injected into thr formation in step (a) with the injected carbon monoxide forms additional hydrogen and carbon dioxide, and (d) recovering the displaced hydrocarbons via the said production well and wherein after step (b) there is injected into the formation via the said injection well a drive fluid comprising water containing dissolved therein from about 0.001 to 1.0 weight percent of an interfacial tension reducer selected from the group consisting of a compound of the formula: ##STR7## wherein r is an integer of from 2 to about 5, s is an integer of from 8 to about 60 and M is selected from the group consisting of hydrogen, sodium, potassium and the ammonium ion, and a compound of the formula: ##STR8## wherein t is an integer of from 8 to about 40 and M has the same meaning as previously described.