A process for enhanced oil recovery from an extraction operation comprises the steps of selection of an appropriate hydrocarbon bearing stratum; providing at least one production well and one injection well; and injecting into the target stratum a slurry formed from sand, viscous liquids or oily sludge, which is delivered at or near formation fracture pressures. Monitoring of bottom hole pressure is carried out, to permit delivery of the slurried wastes in a series of injection episodes, in which the length of the episodes and interinjection periods is determined by maintaining the bottom hole pressure within a preselected range. The position and spread of the slurried wastes within the target stratum may be monitored through the use of additional monitoring steps.