Аннотация:Initiation of the in-situ combustion (ISC) may be accompanied by rapid increase of oxygen concentration in the production fluid. This may cause serious damage to the well equipment by corrosion or explosion.
The most common method for reducing the risk of incomplete oxygen consumption (and oxygen breakthroughs) is pre-heating of the bottomhole zone with the use of well steam treatment (WST) technology. It is possible to optimize the initiation of ISC process - to minimize amount of injected steam, to achieve maximum air injection rate in a fastest way and to ensure that no oxygen breakthroughs to producing wells will occur during initiation of the ISC process.
We propose a method for initiation of ISC based on the developed semi-analytical model. Our approach allows to calculate the increasing air injection rates, from initial value to maximum acceptable value. The method is applied to model prevention of oxygen breakthroughs and to provide fast and safe initiation of an the ISC. Two cases are considered: initiation of ISC in the reservoir with the initial constant temperature and initiation of ISC in the reservoir with the pre-heated zone around injector well. In addition, we develop a method of optimal initiation of ISC after WST that allows to spend a minimum amount of energy and to satisfy the conditions of effective, fast and safe initiation of ISC.
The CMG STARS reservoir simulator was used for testing the developed model. The results which were obtained in accordance with the developed semi-analytical model are in full agreement with numerical experiment.