The In Situ Combustion Method Optimization After Steam Huff And Puff For Mid-depth Thick Heavy Oil Reservoir

As mining method for heavy crude oil, in situ combustion and steam stimulation wastwo kinds of competitive process method. By now, after steam stimulation many times, therewas a series of contradictions for a lot of heavy oil reservoir. In this article the difficulties ofthe exploitation for the deep layer heavy oil and the existing problems after steam stimulationwere analyzed, the necessity of ISC for secondary development of reservoir wasdemonstrated. Besides, the spontaneous development of two-dimensional combustion kettleequipment by laboratory experiments was used to simulate the ISC of thick heavy oilreservoir. The fire dynamic process of the line between site injection wells and productionwells was studied and simulated, including reservoir ignition mode, the selection of the gasinjection speed and ignition power, the reservoir temperature distribution and the oilsaturation distribution at different time, then distribution law of in situ combustion frontcould be judged, and the different factors influence on temperature profile was analyzed. Theresult showed axial temperature site advanced along updip direction, the steady propagationof ISC front was decided by the combined action of all factors. At the same time, numericalsimulation were established with the CMG software, which was about different pattern ofwell for mid-deep thick reservoir ISC, including vertical wells gas injection, the production ofvertical wells and horizontal wells, then based on the simulation result, the oil recovery, oilproduction rate as well as gas/oil ratio change, temperature profile and oil/gas saturation wereanalyzed, after considering various factors the optimal well spacing program was obtained.The results showed gas injection volume and well spacing were the most important factorsthat impacted vertical temperature profile. The vertical displacement efficiency of oil forhorizontal well was better than straight well, and recovery of horizontal well was more thanstraight well. For the dipping formation, the effect of inverted nine spot well pattern wasbetter, taking into account of the gas channeling problem in the late, the way from the up position turn to low position for row well pattern could be used. It provided a theoreticalbasis for the effective utilization of heavy oil resources.