With the development of science and technology, mechanical oil extraction plays a more and more important role in oil exploitation. Compared with the traditional manual operation, its technology is more mature, the operation is more convenient, and the performance is more stable. It plays an important role in the oil field exploitation of various countries in the world. At present, China’s oil field development has gradually entered the later stage of oilfield development after mature development, and the advantages of mechanical mining are more obvious. In recent years, the newly developed dry screw pump has become the main equipment of mechanical oil recovery. It has a very broad application prospect and has injected new vitality into the oil field production in China.
1、dry screw pump type analysis
Dry screw pump is mainly divided into two forms, one is the ground driven single screw pump, the other is the screw pump driven by submersible motor, which are the two main oil production systems in China. The former mainly uses the ground power to drive the rod string to rotate, and finally achieves the rotor low speed rotation to carry out the green lift mining. The latter mainly uses downhole submersible to drive screw pump directly to carry out oil production. These two types of dry screw pump have more market in domestic oilfield production.
2、 Analysis of working characteristics of dry screw pump
As the main system of oilfield production in China, dry screw pump has unique working characteristics and working principle. In view of the shortcomings found in the use, the improvement analysis of dry screw pump is increased. The working characteristics of dry screw pump are described from three aspects of volume efficiency, stator profile and interference.
(1.)Volumetric efficiency of screw pump
Through the experiment, we found that the effect of medium temperature and viscosity on the volume efficiency of screw pump is obvious. In this study, the actual working characteristic curve of the dry screw pump was numerically simulated, and the obvious influence of the stator rubber swelling on the volume efficiency of the dry-type screw pump was discussed. A large number of research results show that the structure of the dry-type screw pump is improved The structural optimization of parameters and working parameters can significantly improve the equipment loss and prolong the service life and working cycle of screw pump.
Through the analysis, we also found that the actual service life of the oil production screw pump often depends on the oil resistant rubber performance of the stator bushing, and the rubber stator is affected by many factors, which directly affects the working characteristics of the screw pump. At present, NBR is used in the research at home and abroad, and the modified rubber derived from NBR is also very effective in improving the service life of the screw pump Effective.
(2.) Stator profile of screw pump
On the basis of analysis and research, a simple modification method of stator profile is proposed to improve the accuracy of bushing profile to improve the sealing performance. The operation is very simple. In order to fully ensure the bushing profile of stator rubber, Han Xiuting thinks that the rubber should be modified according to different rubber formulations in the design of stator mold core, so as to enhance its stability and ensure its rubber to a large extent The profile of rubber bushing.
The deformation law of stator rubber is obvious, especially the deformation of stator rubber profile is more regular, but the research based on this aspect is relatively backward, almost no recognized law. With the development of technology, especially the wireless geometry and physical linearity have played an important role in the detection of the limitations of rubber materials. In these methods, finite element method is commonly used. Rubber has incompressible deformation of elastic material. Based on this research, the effectiveness is studied. The Pann invariant decomposition is introduced into rubber, which plays an important role in enhancing the stability and convergence of displacement solution.
(3.)Interference of dry screw pump
The former Soviet Union first improved the working principle of the screw pump with low head. On the basis of establishing the corresponding volume loss, mechanical loss and empirical calculation, it took the lead to conduct in-depth research and Analysis on the structural parameters and working performance of the screw pump through experiments, so as to understand and grasp its overall working principle and working characteristics. Through the research, we found that the stator lead, rotor diameter and eccentricity of screw pump have certain internal correlation. Only when the numerical value of each structure is reasonable can we ensure its existence and effective operation. The main structure parameters of single screw pump are optimized on the basis of ensuring high efficiency and long cycle working time. Through experiments, experts and scholars concluded that the interference between stator and rotor will greatly affect the actual work of screw pump. Even if we can reduce the volume loss by reducing the surplus, it will also lead to the increase of mechanical loss. Of course, the above analysis is only applicable to low-pressure head screw pump, not applicable to all types of screw pump The screw pump with high pressure head needs further research and analysis.
3、 Technical development and application analysis of dry screw pump production system
The special working characteristics of dry screw pump determine its technical application and implementation process. Dry screw pump can be used for swelling operation under high temperature and high pressure. It can modify and improve the downhole working characteristics to meet the needs of production, and modify the working characteristics and oil well productivity in the future. Only by selecting the pump type reasonably can the lifting coordination between oil well production and dry screw pump be obtained.
It can help to select appropriate oil recovery technology. Dry screw pump can be used for matching process selection of oil production process. There are many choices. In addition to selecting appropriate tubing, it is also necessary to select appropriate sucker rod to help select reasonable parameter setting and driving. Only on the basis of the above work can the design be reasonable and accurate, and the operation can be safe and reliable, and the dry screw can be extended to a certain extent Pump maintenance cycle, improve the actual operation efficiency, better promote the next step of work. To improve the oil production efficiency, through the research and analysis of the working characteristics of the dry screw pump, we can extend the service life and improve the production efficiency, and better promote the production research of the oil field dry screw pump, and make it gradually mature and perfect. As a new type of artificial lifting method, its investment is less, the structure design is simple, the operation is flexible and convenient, and has obvious energy-saving effect. It is the incomparable advantage of the plunger pump and electric submersible pump.