Basic Research And Application Of In-situ Combustion Technology Of Oil Production

In-situ combustion is an oil production method with obvious technological advantagesand great potentials. It is extensively applied to reservoirs, rich in resources, high in oilrecovery and low in cost. But because ISC mechanism is quite complicated, there are stillmany defects in its research which affect its popularization and application and urgently needimproving. Aiming at this practical problem, based on an adequate investigation and analysisof former work and results,The results of this paper provide new theories and new methodsfor the optimization design of ISC technology.The one-dimensional model test of ISC adopts test data to set up a reaction equation ofhigh temperature combustion, reveals the nature of ISC, measures the change of thetemperature field, the temperature of self-combustion, the rate of oxygen application, theconsumption and need of air, the value of air and oil ratio and the visual H/C atom ratio andother ISC basic parameters. The method for calculating these parameters is put forward. Themovement velocity of combustion front is determined and the effects on the combustionstability are also verified. Thus, the research results can provide a scientific base for fieldprogram design.Through the organic analysis of produced crude and the comparative analysis ofcombustion parameters of the crude in different zones, it is found that anthracene, a productof high temperature cracking, results from ISC heavy oil in Liaohe. As anthracene does notexist in the primitive formation, the success of ISC can be concluded if this chemicalcompound (anthracene) can be found in the produced crude of ISC. The material anthraceneis one of the important signs of successful ISC.It is proposed that the oxygen concentration for underground injection is a constant andthe equation of combustion zone shape is also made clear under two different conditions ofvariables. The research shows that the cumulative injected air has a great effect on thethickness of the combustion zones, but neither air demand nor the porosity of formation hassuch a big effect.An equation is established for ISC concentration distribution of underground oxygen. Itprovides a new method for the research of reservoir combustion, determination of combustionsweep and the optimization of injection wells and production wells.The volume equation for ISC zones is established and the factors that affect the volumeof the combustion zone are analyzed. On the basis of that, the formula for calculating the coefficient of ISC volume sweep and for calculating the oil production is established, whichprovides a new theoretical method for ISC technological design and the optimization oftechnological parameters.From a practical perspective, this paper mainly covers the following about ISCtechnology:(1) Calculation of the total need of air of well pattern(2) Determination of the speed of injected air;(3) Calculation of the pressure of the injected air.Hence (1)-(3) decide the injection equipment and operation plan.(4) Prediction the effect of ISC technology. Calculation of the produced crude, the ratioof air and oil, the oil recovery, etc. Hence the judgment of the success in terms of technologyand economy. Not only does the paper proposes a design method, but also gives some designexamples which conform with the specific situation of the oilfields.