The Principle Of VAPEX Technology And Its Application On Thin Heavy Oil Reservoir Recovery In Daqing

As for the geological features and oil properties of thin layer heavy oil reservoirs,this paper makes a systematic research on VAPEX technical principles,theoretical models and application methods.VAPEX effect on oil recovery will be predicted with numerical simulation;furthermore,sand-packing model will be applied to evaluate the experimental results of VAPEX.Analysis shows that the controlling factors on VAPEX is mainly due to the fact that solvents are vaporized,diffused,mixed with oil;oil viscosity is decreased and diluted oil discharges downward under the gravity.According to Fick law,numerical model of VAPEX process is settled.Theoretical model can be applied to analyze the variation of solvent cavity,caculate the production rate of VAPEX quantitatively,which povides a new theory and way to VAPEX process design and optimization of technical parameters.Indoor experiment data verifies the validation of the theory.And the caculation corresponds with the actual value,which proves that this theory can be used to analyze problems in VAPEX process.This paper develops an analogy conerning the similarity between VAPEX process and SAGD process.This method will make the thought more clear,physical meaning of theoretical model more precise,the expression more concise.The experiment verifies that this analogy is applicable and effective.With reference to the common chemical process theory,the author analyzes the process of solvent deasphalting and describes the mechanism and influencing factors of propane taken as a solvent deasphalting.It concludes that propane can be made to deasphalte at 50℃ to 90℃.The result of experiment shows that Jiang 37 heavy oil is very sensitive to temperature,with the increase of the temperature,viscosity decreased significantly;Jiang 37 heavy oil in low temperature 40℃ is manifested as non Newtonian Bingham plastic fluid;its specific heat capacity builds up with the increase of temperature.The value of specific heat capacity changes a lot,ranging from 1.684 to 4.4939J at 20 ℃ to 300℃.Thermal parameter decreases with the increace of termpreture and is very close to the value.Thermal conductivity changes little from 0.1196 to 0.165w/(m-℃)at 20℃ to 300℃.Numerical simulation research results show that it is propane rather than butane that is more suitable for VAPEX;Well pattern of one horizontal well and four vertical wells is an optical choice.Parameters of optimization results show that the velocity is from 6000m3/d to 8000m3/d.When fluid velocity is 10m3/d,the production time is six years and recovery efficiency can reach 68.88%.Indoor experiment and numerical simulation research results show that VAPEX technology is more applicable to heavy oil reservoirs of Daqing.Indoor experiment indicates the higher the temperature is,the better the effects of propane gas injections are under the same number of PV injection.When gas drive is transformed into waterflooding,recovery factor is increased to 64.05%in 28 ℃.When the transformation happens in 50 ℃,recovery factor is increased to 74.69%.Temperature has an obvious effect on oil drive.With the increase of propane injection,recovery factors are soaring.When the injection rate of propane is 0.3PV,recovery factor will be increased to 37.22%by transformation(gas drive to waterflooding).When the injection rate of propane is 0.7PV,recovery factor will be increased to 66.53%.As the author takes the cost into consideration,the rate of propane ranges from 0.3～0.5PV.The higher injection pressure is,the better results of oil drive are,which goes with recovery of propane gas drive under different pressure conditions.Huff followed by gas drive then waterflooding is superior to gas drive followed by huff then waterflooding.After propane is injected,the lower water content is,the higher recovery factor is.Characterization results indicate that the composition of oil experienced a series of changes before and after propane’s extraction.That’s to say,the light component of oil is increased,but the heavy component is decreased.As a result,the fat group of side chain becomes richer.VAPEX for recovery thin layer heavy oil is economical and extraction solvent can be recycled.VAPEX can improve the quality of recovery of heavy oil.The author proposes the usage of vapor extraction technology for thin layer thick oil.This research provides for instructional suggestions on the improvement of development effect of heavy oil in periphery of Daqing so as to strive for more thorough and more effective stimulation.Meantime,the study also gives aid to people who intend to make a design on development of oil field and oil production.