| The in-situ combustion is a cost-effective technology for heavy oil development.For thick oil layers,the three-dimensional ISC process combines the advantages of conventional ISC process with gravity drainage,which can greatly improve the sweep efficiency and final recovery ratio,so the development efficiency is better than planar ISC process.For G2-4-6 thick heavy reservoir,this paper combines its reservoir characteristics with the existing well pattern,designs a new ISC process using well patterns which combines vertical wells and horizontal wells.And laboratory experiments have been carried out on this kind of ISC process.Through analytical experiments(TGA,etc.)and one-dimensional combustion tube experiment,the oxidation kinetic characteristics of the crude oil in the test area were studied and basic combustion parameters were obtained.The results show that this block is suitable for ISC process.Through three-dimensional physical simulation experiments,it is verified that this ISC process can achieve better vertical sweep efficiency.Also,the propulsion process and the spreading law of the combustion front were studied,the oil layer during ISC process can be divided into 4 zones: burned zone,coke zone,oil barrier and residual oil zone.At the same time,the technical risks of this type of ISC process were put forward,namely the half-way flameout and the combustion front breakthrough,and corresponding control policies were put forward for these risks.The fire-flooding scheme was designed for G2-4-6 block,reasonable injection and production parameters were given,and the chemical assisted ignition method was selected,supplemented by steam stimulation technology,in this way,a stable and effective ISC process can be achieved.The ISC development scheme was numerically simulated and it is expected that the ultimate recovery of the experimental well group will reach 58%.At the same time,according to the situation faced by the G2-4-6 ISC pilot site,corresponding control policies are given. |
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