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, 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.
Wanfu, Zhou (Daqing Oilfield Co. Ltd.) | Guochen, Shi (Daqing Oilfield Co. Ltd.) | Gang, Cao (Daqing Oilfield Co. Ltd.) | Mingyan, Lu (Daqing Oilfield Co. Ltd.) | Mingzhan, Chen (Daqing Oilfield Co. Ltd.) | Yu, Hou (Daqing Oilfield Co. Ltd.) | Yongxin, Liu (Daqing Oilfield Co. Ltd.) | Mingyi, Zhang (Daqing Oilfield Co. Ltd.)
This paper presented the development of Progressing Cavity Pump (PCP) technologies in Daqing Oilfield during the past 27 years, covering the successful experiences and lessons learned. The history of PCP lifting technology development was reviewed in the round. Several main PCP techniques were presented in detailed as well, including high efficiency and low profile PCP drivehead, hollow rotor PCP water flushing technique, PCP trouble-shooting technique, and PCP logging technique, etc.
Daqing Oilfield was the largest continental oilfield in China developed from 1960. Beam pumping units was the main
artificial lift method. To date, there are more than 40,000 beam pumping wells. PCP was applied in Daqing Oilfield from 1983. In the past 27 years, the scale of PCP increased at a higher rate. Till the end of 2010, 6,000 plus PCP wells were applied in Daqing Oilfield. PCP has become the second largest artificial lift method in Daqing Oilfield.
To date, a series of PCP products have been developed covering the displacement and lift arrangement for different blocks in Daqing Oilfield. Based on the study and experiences for years, a set of completed PCP system design methodology was also created for water flooding, polymer flooding, ASP flooding and other complicated conditions. The fast improvement of PCP mainly resulted from two respects: Firstly, the quick development of PCP production techniques. The adaptability and reliability of elastomer was improved effectively and matching techniques were developed as well. Secondly, the requirement of low energy consumption and environmental protection in petroleum production policies enhanced the application of PCP technologies considerably.
This paper applied a successful case study of a novel technology developed in the mature oilfield which could be a great reference for the industry.
Daqing Oilfield was discovered in 1959. It is the largest continental oilfield and the petroleum industry base in China. In the beginning of the development, natural flowing was the main producing method of the oilfield. From 1982, artificial lift method was widely used in the oilfield manily including beam pumping system and ESP. Till the end of last century, nearly 30,000 beam pumping systems and over 2,000 ESP pumping systems were in operation in Daqing Oilfield. See Figure 1.
In 2000, the average water cut for the whole oilfield reached nearly 90%. High cost on investment and operating of beam pumping system has become a bottleneck problem influencing the economy of oilfield development. In 2002, the total power consumption of artificial lifting systems was nearly 10 billion kW•h, which was over one third of the whole oil field's power consumption.
From 1990s, polymer flooding, APS flooding were applied in Daqing oilfield. The recovery of the oilfield improved
considerably. On the other hand, the failure rate for the artificial lift system increased dramatically due to the changing
properties of production fluid. For example, the average running life of beam pumping systems in polymer flooding areas from more than 600d down to 270d. Cost for overtime also increased by ten million RMB per year.
As for ASP flooding area, the results were even more serious. Due to high scaling in pumps and strings, the average running life of the beam pumping system was less than 60d, while the shortest running life was within a month. Artificial lifting technology has become a "bottleneck?? problem for Daqing Oilfield in EOR period.
PCP system was chosen to be the first alternative. It has lower investment and operation cost, higher efficiency, and a high viscosity and sandy liquid production.