Research On High-efficiency Mixing Technology Of Heavy Oil Mixed With Thin Wells

As one of the important energy resources in 21th century,the high efficient mining technology for heavy oil reservoir has been one difficulty in human's exploration.The Tahe Oilfield,one world class region to exploit in china,is still reforming its heavy oil recovery technology.At present,the main productive mode of heavy oil dilution wells in Tahe Oilfield is combining technology of blending light oil for viscosity reduction and pumps suited to heavy oil,but it is faced with following problems:abnormal wellhead production,serious broken off of sucker rod and shortage of light oil.Therefore,it is urgent to find out the root cause of existing problems in heavy oil wells and improve the technology of blending light oil.In view of the above questions,this article surveyed the developments of heavy oil wells in Tahe oilfield specifically and designed a new blending light oil model combining the key structure of pump with oil tube and casing pipe by Solidworks.Further more,this article came up with a transient numerical method based on pressure boundaries,which achieved synchronous solution combining pumping motion and flow field calculation with dynamic mesh technology and UDF programming.With the numerical simulation software-Fluent,this article has calculated the results of blending in casing pipe,blending with SK stactic mixer and automatic rotating mixer.Under the same external conditions,these results were compared and analyzed,which indicate following points:Firstly,The results reflect the real situation of the blending effect more intuitively,and reveal the fundamental factor influencing the situation of abnormal wellhead production—because of continuous injection of thin oil and pumping of oil pump,the height of light-heavy oil dynamic surface changes every time.While there is only one entrance to oil tube,which lead to irregular inflow of light and heavy oil into the tube,resulting in alternate appearance of heavy oil with light oil.Secondly,comparing the diluting results with different numbers of SK mixing elements in oil tube,this article has found that SK mixing elements can not change the abnormal phenomenon of wellhead.The more SK elements are installed,the more heavy oil flow into oil tube,the more pressure drop and velocity decrease.And the middle length of SK static mixer is the best choice than anthor two lengths to decrease the viscosity of heavy oil.Thirdly,comparing different blade inclination angles of automatic rotating mixer in oil tube,this article has found that installing automatic rotary mixer can increase blending speed and greatly promote the light oil flowing into the oil tube,resulting in the waste of light oil by pumped out without diluting heavy oil.And under the rotating action of automatic rotating mixer,the flow state in oil tube will change from laminar to turbulent,which can lead to pulsation phenomenon.In particular,30°blade is the most serious in causing turbulence while 45°is relatively stable.Based on above research,this artcle puts forward a new thinking for blending light oil viscosity reduction,and designs a new blending technology-technology for certain viscosity reduction ratio with blending valve.The results of Fluent simulation show that using the new certain ratio blending valve installed in bottom of oil tube with now available technology of blending light oil can control the flow rate of light oil and heavy oil per stroke,and eliminate abnormal production and stabilize viscosity reduction ratio.Further more,it can save light oil resources,greatly improve the production effect of heavy oil dilution wells.