| The heavy oil of the 10th area in the Tahe oilfield based on the Tarim Basin, can flow at the subsurface temperature. But the flowability of the heavy oil is worse when the temperature along the wellbore is decreasing during producing. The Tahe oilfield has been studied the wellbore-rising technologies and improved them. But as the oilfield is growing, the thin oil source has been unable to meet the increasing demand of heavy oil unceasingly. The containing water of oil wells is increasing, the dilute effect with the thin oil is worse and the cost is getting higher. This paper takes example by the phenomenon that the foamy oil in the cold recovery of the heavy oil can reduce the viscosity of the heavy oil. And to explore the method to reduce the viscosity of the heavy oil in the wellbore.There are three major types of the conventional viscosity reducing methods in the borehole:made with thin oil, wellbore electrical heating and the wellbore chemical method. The three kinds of viscosity reduction process have their own advantages, but they all have limitations too. Such as the cost is high for the dilution with thin oil and wellbore electrical heating which lead to the economic limitations. The cost of the wellbore chemical is relatively lower and easier to be achieved, but the later sewage treatment and the emulsion breaking are very troublesome problems;It could be a new method to produce the heavy oil for the low viscosity and the good mobility of the foamy oil in the cold recovery of the heavy oil reservoir. Investigate the related material of the foamy oil. The commercial domestic study of foam oil is only on the factors of foamy oil and some introduction of the models simulating the process of the foamy oil in the formation. And the studies introduced overseas of foamy oil have been relatively mature. On indoor research, the on-site application and the numerical simulation, there are a large number of documents on the reference. Yet the commercial dispute and uncertainty factors have always exist;We filtrated the best blister system-the B3E system based on the foamability, stability and the the comprehensive characteristics of the seven kinds of the foam agents using Waring Blender and orthogonal experiment methods.We studied the factors influencing the atmospheric stability of the foamy oil after understanding the viscosity-temperature relations of the degassing crud oil and the main factor of the viscosity of the heavy oil being the high content of pectin and asphalt. The foamy oil could not be achieved if the viscosity of crud oil is too low, well the high-viscosity crude oil is easy to form foamy oil with high quality and stability. When the salinity is 6+0.6×104mg/L, the volume and half-life period of the foamy oil have dropped sharply. There is an optimal oil-water ratio range for the stability of foamy oil. That is, in this range, the stability of the foamy oil is very good. In certain temperature range, as the temperature rises, the volume, the half-life period and the comprehensive index FCI of the foamy oil is decreased. And there is the rang of the shear rate that with the shear rate increasing the volume and the half-life period of the foamy oil increase.we conduct the wellbore physical simulation experiments at relatively appropriate experimental conditions based on the experiments to screen a suitable blister system. The results are as follow:the system of B3E has good dispersion ability which makes the heavy oil and the solution mix better, thus it can improve the liquidity of heavy oil. In the process of forming foamy oil the gas'participation can lead more bubbles, and cause the solution more evenly mixed with oil. Forming foamy oil needs the enough amount of the foaming system, and the ratio between oil and solution has an important influence to form foamy oil. The smaller the ratio is, much uniform the solution formed in the reactor and the line be, the easier the solution outflow, the more the bubbles form, the lower the fluid viscosity be. |
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