Steam Paving To Help Predict The Model Of Gravity Drainage Production

The development and utilization of heavy oil have got more and more attention, owing to the increasing demand of oil resource coupled with the reduction of conventional oil and gas reserve. SAGD, as a advanced technology for heavy oil exploitation, allows a relatively higher recovery, which is more and more widely applied in recovering heavy oil. Study on drainage model of SAGD is further deepening and expanding with the development of SAGD. Oil field production also draws higher requirement for the prediction accuracy of production by SAGD. The state of domestic and international SAGD methods for heavy oil recovery, is reviewed in this article. This paper summarized current drainage calculation models. The production predicted with current models is only compared with laboratory-coreflood production by SAGD but instead with field data, which cannot prove the reliability of these models adequately. The predictive results of various models, some of which include unrealistic assumptions, differs greatly from each other. In view of this problem, the existing models were studied in this paper. (1) Butler drainage model was studied. Oil production rate was calcuated in its rising and horizontal expansion phase. This paper sumed up two modified methods of Butler drainage model. Two corresponding calculation program were programmed according to the results obtained by the two modified methods. The curves of oil production rate and cumulative production which changes with time are drawed in use of the program. The effects of permeability and reservoir thickness on oil production rate were discussed. (2) Linear drainage model was studied. Oil production rate was calcuated in its rising and horizontal expansion phase combining linear model and Butler model. The calculation program was programmed. The curves of oil production rate and cumulative production which changes with time were drawed in use of the program. The effects of permeability and reservoir thickness on oil production rate were discussed. (3) Linear hierarchic model was improved. The new linear hierarchic model makes the calculation become closer to the reality. Meanwhile, we programmed the calculation program according to linear hierarchic model, so as to obtain the curve of velocity of oil drainaging and cumulative production which changes with time. The effects of permeability and reservoir thickness on oil production rate were discussed. (4) Circular hierarchic model was improved. The new circular hierarchic model makes the calculation become closer to the reality. Meanwhile, we programmed the calculation program according to circular hierarchic model, so as to obtain the curve of velocity of oil drainaging and cumulative production which changes with time. The effects of permeability and reservoir thickness on oil production rate were discussed. (5) we made unsteady heat conduction infinitesimal model on the basis of the four models, which takes heat conduction before the steam chamber changing with time into consideration. Also, this paper programs curve of the steam chamber, the steam chamber movement speed curve, the heat transmission depth curve and drainage speed curve by using established model. The effects of parameters such as reservoir permeability and reservoir thicknesson on the curve were discussed. Finally, the five kinds of model were used to calculate the drainage speed, and compared it with the actual record, finding that the calculation results of the unsteady heat conduction infinitesimal model was the most close to the actual oil production rate. This research result can be applied in the oil field.