Optimization And Dynamic Prediction Method Of The Heavy Oil Reservoir Steam Huff And Puff Steam Injection Parameters

The heavy oil is the important resource of 21 century. To use the heavy oil resource is an important means to lessen the crude oil pressure in the future. To economically and efficiently exploit the heavy oil has important realistic and strategic meaning to our country. Because most of the heavy oil is produced by thermal techniques, it is particularly important to study of the thermal models, such as the models of cyclic steam and steam drive.In this paper, the basic theorise of thermal process, the conversation laws of energy, momentum and mass in the wellbore and formation, are applied to establish the models of temperature field in injection wellbore and formation. According to the material balance equation, the changes of oil saturation in the formation and relative permeability are calculated with time. On the base of the energy balance, the analytical cyclic steam stimulation model is established. The main contents are following:1. Considering the steam overlay phenomena, combined with sweep efficiency, a new equation to calculate the maximum heated radius is presented.2. Anatomise the energy change of the oil zone and injection steam during soak period, the reasonable calculation formula to calculate the time of soaking is deduced.3. The thermal balance equations are established and applied in each stage of cyclic steam stimulation, In the strata, because the commutation of the heat energy is continuous, the calculation should be connected up properly in the sequence of injection period, soak period and production period. In the injection period, the heat loss of the wellbore, pressure loss of the wellbore, the heat loss in the cap rock and base rock and heat conduction of the steam/liquid interface are mainly considered; in the soak period, the heat loss, the change of pressure and temperature are considered; in the production period, besides the heat loss, the heat carried by the production liquid and the change of pressure and temperature are also considered.4. For the multicycles, the effect of remaining heat form last cycle on the heated radius and the soaking time are considered. Consequently, remaining heat also influences the production performance of the following cycle.5. Using multi-index optimum method to optimize the parameters of the cycle steam stimulation. The optimized results are close to the actual values.6. To apply the models and methods to carrying out sensitivity analysis and calculating the actual example of the ninth area of Kelamayi in Xinjiang. The calculated results indicate that the mentioned method needs a small amount of parameters, shorter time, and the calculation precision satisfies the actual requirement. In conclusion, the study has practical valve to the heavy oil development.