Elastomer is the core component of progressing cavity pump (PCP) which influences the running life of PCP considerably. Conventional elastomer performance tests only show basic mechanical and physical properties mainly simulate the static mechanic performance of elastomer. Numerical simulation indicates that dynamic performance is much more valuable in evaluating PCP's running life, while elastomer's dynamic test has not common criteria in the industry, especially for dynamic fatigue property test. This paper presents a novel simulated experimental design which could effectively evaluate dynamic fatigue properties of PCP elastomer.
Based on the operating conditions of PCP lifting system, a special experiment system has been designed and tested. It consists of power transmission system, friction pair system, and temperature control system. After implementing a series of contrasted tests, a special structure of elastomer sample and testing process were designed which showed best performance in accelerating dynamic fatigue process of elastomer as well as to simplify simulated test principle.
In order to verify the evaluation result of this fatigue testing system, three candidate elastomer formula (sample A, B, C) were evaluated. Experiments showed that dynamic fatigue properties of sample C were better than A and B. The fatigue properties of sample A was the worst. Statistics indicated that average running life of elastomer A was about 550 days, while running life of Elastomer B was 590 days and Elastomer C was 670 days. The application results had the same principle with experimental results. Experiments indicated that this simulated experimental system could describe the dynamic fatigue performance directly and clearly.
This paper presented a new experimental design which could evaluate the dynamic fatigue properties of PCP elasomer based on simulating PCP's operating conditions in practice. This experimental system has been applied to guide the design of elastomer formula and showed good results. This experimental system and testing process are of great significance in evaluating PCP elastomer's performance and developing high performance PCP elastomer in various operating conditions.
Chen, Mingzhan (Daqing Oilfield Co., Ltd. Northeast Petroleum University) | Cheng, Jiecheng (Daqing Oilfield Co., Ltd.) | Zhou, Wanfu (Daqing Oilfield Co., Ltd.) | Huang, Youquan (Daqing Oilfield Co., Ltd.) | Sun, Xiaoming (Daqing Oilfield Co., Ltd.) | Cao, Gang (Research Inst. Petroleum Exploration and Development, PetroChina) | Han, Song (Daqing Oilfield Co., Ltd.) | Wang, Guoqing (Daqing Oilfield Co., Ltd.) | Jiang, Tao (Daqing Oilfield Co., Ltd.) | Li, Ping (Daqing Oilfield Co., Ltd.) | Wang, Yanyan (Daqing Oilfield Co., Ltd.)
Scaling issue of artificial lift systems is the main bottleneck for ASP flooding, and has considerably negative influence in commercial stage. In the past decade, different anti-scaling technologies have been developed and applied in Daqing Oilfield. However, high pump failure still exists in severely scaling producers. This paper presents an innovative artificial lift method – a patented bailing pumping unit production system, which has been applied successfully in field test stage in Daqing Oilfield.
The system consists of soft plunger, special designed wire line, winch system and surface control. Produced liquid mixed with large quantity of scale particles is lifted to surface by the soft plunger connected to wire line. The plunger is made of high molecular materials and steel skeleton support which ensures good flexibility and reliability after long term of operation in abrasive environment. The wire line is specified designed and processed to enhance operation life. It connects downhole gauge and surface control. Down hole pressure can be monitored in real time, which provides references for adjustment.
This innovative bailing pumping unit production system has been applied in 80 wells in 3 ASP flooding blocks with severe scaling issue in Daqing Oilfield. The average running life was improved from several weeks to 710 days. Considerable benefits have been achieved by the 60% operation cost decline. It has been the premier artificial lift method for the severely scaling producers. Additionally, there is no need for flushing or acidizing treatment to deal with scale deposited in downhole pump, rod string, and tubing string compared with pumping unit production system in ASP flooding, which significantly reduces normal management intensity and cost.
Field test showed that this innovative bailing pumping unit production system has outstanding scale resistance capability for severe scaling wells in ASP flooding. It also provides a great reference for other oilfields in worldwide with similar issues both in ASP flooding and high salinity conditions.
Cheng, Jiecheng (Daqing Oilfield Co. Ltd.) | Zhou, Wanfu (Daqing Oilfield Co. Ltd.) | Wang, Qingguo (Daqing Oilfield Co. Ltd.) | Cao, Gang (Daqing Oilfield Co. Ltd.) | Bai, Wenguang (Daqing Oilfield Co. Ltd.) | Zhao, Changming (Daqing Oilfield Co. Ltd.) | Luo, Meie (Daqing Oilfield Co. Ltd.)
Pilot tests commenced from 1980s in Daqing Oilfield have proved that ASP flooding could improve the recovery rate by 20% based on water flooding, while scaling issue in producers was the only factor which made it hard to reach that objective. Investigation in site indicated that more than 70 percent producers had scaling issues, and scaling types and degree in ASP producers varied dramatically in different wells and different period. In the peak of scaling period, the averaged running life was only a couple of months.
A project focused on the harness of scaling issue in ASP producers was implemented from 2002. In the first stage, the study aimed at getting the scaling principle in ASP producers. A series of monitoring and analysis on producing fluid’s ion concentration were implemented in different APS producers. The scale deposited on tubing in different depths were picked out and analyzed. The scaling mechanism of ASP producing liquids in artificial lift systems were created which presented the varying principle of scaling ions as well as the characteristics of scale in ASP producers. A set of scaling principle prediction plates was also created with a success ratio being above 90%.
In the second stage, a series of anti-scaling artificial lift techniques were developed including new anti-scaling pump, chemical scale removers and scale inhibitors, and other matching techniques. The new anti-scaling techniques were put into application from several wells up to near 1,000 wells. The number of pump failure was decreased by 4.13 percent as well as the operating cost by 72.77%.
The technical breakthrough in production engineering improved the operating life of ASP producers considerably. It applied solid foundation for ASP flooding to become a beneficial method for mature oilfield development in commercial scale.
Key words: ASP flooding scaling issue in producers, scaling principle, anti-scale artificial lift technique
Chen, Jie (University of Science & Technology of China) | Wu, Hengan (University of Science & Technology of China) | Liu, He (PetroChina Research Inst. Petr. Expl/Dev) | Wang, FengShan (Petrochina Daqing Oil Field Limited Company) | Shi, GuoCheng (Petrochina Daqing Oil Field Limited Company) | Cao, Gang (Petrochina Daqing Oil Field Limited Company) | Sun, YanAn (Petrochina Daqing Oil Field Limited Company) | Sun, ChunLong (Petrochina Daqing Oil Field Limited Company) | He, Yan (Petrochina Daqing Oil Field Limited Company) | Ge, WeiTao (PetroChina Daqing Oil Field Limited Company)
Progressive cavity pumps (PCPs) have been widely used as an artificial lifting device in various oilfield productions due to their numerous advantages. However, some problems still exist during practical applications. In order to improve the performance and promote the application, it is of great significance to optimize the design of PCPs.
In this study, we established a finite element model of PCP, which consists of the stator, the rotor, the lifted fluid and the fluid-solid interaction. The controlling equations of solid deformation and fluid dynamics are solved using different solvers for solid domain and fluid domain respectively, and their results are exchanged through the fluid-solid interface. Partitioned solution algorithm is employed to tackle the problem of this two-way fluid-solid interaction.
For specified design parameters, our computed laden torque and volumetric efficiency of PCP agree well with experimental results of laboratory test, which can verify our model and simulation method. Furthermore, the developed model is used to optimize the design parameters of PCPs, which primarily include interference, stator thickness, elastic modulus and Poisson’s ratio of stator. The goal is to choose the appropriate parameters to make the best performance of PCPs. We studied the influence of these parameters on the main performance of PCPs such as laden torque, volumetric efficiency. According to the simulation results, the interference and stator thickness are found to be the two main factors influencing the performance. The influencing rules are summarized, and a comprehensive optimization system of the design parameters is established. Based on these results, we can choose the appropriate parameters and optimize the design of PCPs. Our work can be of great significance for guiding the design and optimization of new PCPs.
Surface-driving single-lobe progressive cavity pumps (PCPs), which are a kind of artificial lift devices devised by Moineau in the 1930s (Moineau, 1930), have been commercially used for lifting liquids in oil production mainly in heavy oil fields. They have unique technical advantages such as low investment, simple structure, easy operation, remarkable energy saving effect and wide application (Liu et al., 2005; Wu and Li, 2010). PCPs in their simplest form consist of a single-threaded screw (rotor) turning eccentrically inside a double-threaded nut (stator), forming consecutive cavities separated by seal lines, as illustrated in Fig.1. As the rotor moves, the cavities move helically and the fluid is promoted from low to high pressure cavities (Moreno and Romero, 2007).
Chen, Jie (University of Science and Technology of China) | Liu, He (Research Institute of Petroleum Exploration & Development) | Wang, Fengshan (Petrochina Daqing Oil Field Limited Company) | Shi, Guocheng (Petrochina Daqing Oil Field Limited Company) | Cao, Gang (Petrochina Daqing Oil Field Limited Company) | Sun, Yanan (Petrochina Daqing Oil Field Limited Company) | Sun, Chunlong (Petrochina Daqing Oil Field Limited Company) | Ge, Weitao (Petrochina Daqing Oil Field Limited Company) | Wu, Hengan (University of Science and Technology of China)
During the operation of Progressive Cavity Pumps (PCPs), the problem of internal slip which defines the pump performance in terms of volumetric efficiency and lifting capacity always occurs. However, due to the complex geometrical structure and coupling interactions between the stator and the oil lifted, it is difficult to solve the internal slip analytically.
In our study, a new finite element model of PCP with fluid-solid interaction is developed to investigate the internal slip. We established the simulation models of fluid and solid respectively, solved the control equations of them in different solvers and exchanged the results through the fluid-solid interface. Partitioned solution algorithm is employed to tackle the problem of two-way fluid-solid interaction.
Two leakage mechanisms, longitudinal slippage and transversal slippage, were found from our numerical simulation results. For specified design parameters, the fluid leakage can be computed with different hydraulic pressure, thus the volumetric efficiency of PCPs can be obtained. Our computed volumetric efficiency is consistent with experimental results of laboratory test, which can verify our model and simulation method. Furthermore, we studied the influence of different material and structure parameters on internal slip of PCP. The developed model could also be used to compare the volumetric efficiency of different PCPs and optimize the design of PCPs. Our work can be of great significance for the optimization design of new specified PCPs.
A three-dimensional finite element model for Progressive Cavity Pump (PCP) is constructed. The steel stator is simplified as a rigid body and the deformation of the rubber rotor is considered in the model according to the characteristic of the stator and rotor materials. The laden torque of friction due to the interference between stator and rotor is calculated with the model. The obtained numerical results are consistent well with experimental data. The effect of parameters on laden torque is performed and discussed. The parameters include the amount of interference between stator and rotor, eccentricity of the track of the rotor moving etc. The results demonstrate that the amount of interference between stator and rotor is the major factor of influencing the laden torque and the laden torque reduces as eccentricity decrease.
In the past 50 years, the oil production of Daqing Oilfield has maintained 50 million tons (near 350 million bbls) per year for 27 years. To date, Daqing Oilfield is still the largest continental oilfield in China. Separated layer development technology is one of the key techniques contributed to this great achievement. In order to monitor dynamic performance of separated layer production, it was necessary to implement logging technique periodically in a large number of selected injectors and producers. Due to the limit of annulus size is too small for sensor to be run into down hole of progressing cavity pump (PCP) wells, traditional PCP system design couldn't meet the requirement of well logging for separated layer production.
Since separate layer development technology is more and more popular in oilfield development, PCP logging technique has become a bottleneck issue which limited PCP application in larger scale. This paper presented an innovative design for logging technique in PCP wells. In this design, a unique drive head design was developed as well as several special downhole tools which applied the path for sensor and wire to be run into the appointed place.
Till the end of 2009, this technique has been applied in more than 200 PCP wells in Daqing Oilfield. The operation was simple and safety, the successful ratio was 95%. This technique could also be applied in other conditions which has a brilliant future.