Quality Reliability Test and Improvement of the Main Body of Filter Element

Abstract: Combining with the actual situation of the oil production site, through a comprehensive analysis of the manifestations of filter element failure, the filter element material, main tube wall thickness, and water hole density are used as the three main reliability factors that affect the life of the filter element on-site, and the pole is reasonably determined. Scientifically design the test plan; through the screening test of the filter element body, it is determined that the filter element body is economical and reasonable and meets the needs of the site. The new filter element body realizes the improvement of the pressure strength of the filter element while maintaining the water injection flow rate, and the reliability is enhanced ? The main body of the new filter element is in a normal working pressure environment. The average use time is 3 () days, which is 3 times that before the improvement. It adopts a removable filter structure, which is convenient and quick to replace the filter, reduces the labor intensity of the workers, and can effectively save the cost of the filter element. The promotion and application prospects are broad.

Whether a product can meet the characteristics of the specified requirements is mainly evaluated from two aspects: first, whether the performance of the product meets the technical indicators that meet the functional requirements; second, whether the functional requirements can continue to be met in the process of production, the former is the technical performance of the product The problem; the latter is the reliability problem of the product, which studies the relationship between the possibility of the product meeting the specified function and the T working time, the reasons for the failure to meet the specified function and the improvement measures. Therefore, reliability is the main content of ensuring product quality.

At present, crude oil prices are operating at a high level. Oilfield production companies must take effective measures to maintain high extraction efficiency. On the other hand, it is necessary to adapt to the needs of building a harmonious development society and conservation-oriented industries, and reduce environmental pollution. Reducing production costs Henan Oilfield is an old oilfield in eastern my country. In 2004, the comprehensive water cut of the thin oil old oilfield reached 92.4%, and the recoverable reserves reached 79.6%, which has entered the late stage of exploitation. Old oil wells have fully entered the stage of water flooding and even tertiary oil recovery: in order to compensate for the energy loss of the formation caused by high liquid production, it is necessary to ensure the large injection water required for efficient production, and at the same time to ensure that the injected water does not cause secondary formation due to water quality problems. Pollution. There are high technical requirements for the quality of the injected water. Therefore, in the development of crude oil water injection, the on-site reliability of the main body of the water injection filter directly affects the production, economy and safety of crude oil mining enterprises. The large amount of wastewater produced by the oil well produced fluid after dehydration is injected into the formation through certain technical measures. The purpose is to maximize the use of water resources on the one hand, and to avoid the environment caused by the discharge of wastewater from the industry. damage. In order to meet the requirements of formation water injection pressure and water quality. The treated T industry sewage is pressurized by the Zengle pump at the oil production metering station, filtered by the water injection filter, and transported to the water injection well to be injected into the formation to achieve the purpose of water injection. Current status of the use of water injection filters Henan Oilfield currently uses sewage reinjection for water injection development. The re-injected sewage contains a certain amount of fine particle suspended solids and slick oil. To ensure the quality of water injection. Need to use water injection filter to filter the re-injection sewage. The slick oil and impurities in the sewage are blocked on the filter screen outside the filter element through the filter element in the filter. Avoid contamination of the ground. The water injection filter consists of a cylindrical shell and a filter element. See Figure 1 for its working principle. The bottom of the filter housing is the water outlet. 1:3 connection with water injection well: outside the filter

There is a water inlet on the lower side of the shell, which is connected with the water inlet of the booster pump in the treated oil well liquid production sewage metering station. The filter element is mainly composed of the filter element body, upper and lower glands. The pull rod and the filter are composed of 4 parts, and the filter is wrapped on the main body of the filter element during operation. Then fix it by the gland and the tie rod. The main body of the filter element is usually a mesh-shaped tubular material. It is a key component of the filter element and plays a vital role in the service life of the filter element. Figure 2 is a schematic diagram of the structure of the filter element.

During the water injection process, the dirty oil and impurities are continuously filtered out and accumulated on the filter screen outside the main body of the filter element. Blocking the water hole causes the pressure difference between the inside and outside of the filter element body to increase continuously. When the pressure difference reaches a certain level, the filter element body is crushed and damaged. Frequent replacement of the filter element body. Not only increases the cost of oil extraction. It also has an adverse effect on the quality of water injection and the formation environment. A total of 18 water injection wells in Henan Oilfield Shuanghe Oil Mine were equipped with water injection filters. In 2003, a total of 816 water injection filter elements were replaced (times), and the cost of filter elements reached 1.06 million yuan. Among them, the main body of the filter element is damaged 507, the frequency is the highest, accounting for 62.3% of the total (see Table 1), and the average single-well replacement of the main body of the filter element per year reaches 28.

This shows that. Improving the quality and reliability of the main body of the filter element is an urgent production technical problem to be solved

The total length of the filter used in this oil mine is 920mm, the outer diameter of the filter element body is 58mm, the wall thickness is 1.2mm, and there are 3500 water holes with a diameter of 5mm evenly distributed on it. The working environment pressure is between 18-20MPa, and the main material of the filter element is ordinary 45 steel. Through a comprehensive analysis of the manifestation of filter element failure, combined with the working principle of the filter, it can be known that the main body material of the filter element, the thickness of the tube wall, and the density of the water holes are important factors that affect the quality and reliability of the main body of the filter element. Therefore, we take the material of the main body of the filter element, the thickness of the tube wall, and the density of the water holes as the main technical factors that affect its reliability. The different levels of the three factors and their cooperation are designed, and they are screened through field experiments to reveal the defects in the design and manufacturing of the experimental objects. Evaluate its reliability objectively, and then select a filter element that is economical and reasonable and meets the needs of the site.

Experimental design and implementation

Reliability experiment is a general term for testing to improve or verify the reliability of products (including systems, equipment, parts and materials). Life test is a very important part of reliability test. It is a test for evaluating and analyzing product life characteristics. Regarding the issue above. We use the existing mining conditions. Under the premise of ensuring that the filter element's water flow and injection pressure meet the injection requirements, the reliability screening test is carried out on the design of different filter elements. To achieve the purpose of extending the service life of the filter element, aiming at the above three reliability factors. According to the existing technical strength of the oil production team and the site 1=mine situation. First, we determine the three poles respectively, and carry out the experimental design. Orthogonal experiment design is mainly to apply the orthogonality principle of "balanced dispersion, neat and comparable" in mathematics to rationally arrange related experimental programs. Through the implementation of the program. Observe and study the degree of influence of various factors on the reliability of the filter element under the interaction of different potentials from many aspects, and determine a certain scheme or a certain combination of factors in the test as the best design scheme. Determine the final process parameter design plan through the experiment of the plan. Therefore, we use orthogonal design to implement the reliability test of the filter element body.

We list the filter element material as factor A, the first pole A1=45 steel pipe, the second pole A2=35CrMo steel pipe: the main wall thickness of the filter element is listed as factor B, the first pole B1=3mm, the second pole B2= 5mm; the number of water holes is listed as factor C, the first pole C1=1200 holes, the second pole C2=800 holes. After the factors and levels are determined, use the L(2) orthogonal table (see Table 2). In addition, in order to make the test results comparable. The test wells are uniformly set in the 23-station H40HD3 well of the 5th team of Shuanghe Oil Mine, and when the pressure difference between the inlet and the water inlet is selected as 1.5MPa, the damage of the main body of the filter element and the water passing capacity (compared with the injection rate) are used to judge Experimental results. Experiment 1. A1B1C1: The filter element material uses 45 steel pipes, and the main tube wall thickness of the filter element is 3mm. The number of water holes is 1200 holes. After 18 days of field application, the inlet and outlet pressure gauges showed a pressure difference of 1.5 MPa. After removing the filter element from the filter, it was found that the middle part was deformed. Before replacing the filter element, the flow rate was measured by an ultrasonic flowmeter to be 88m3/day. It meets the requirement of 72~88m3/day for the daily injection volume of the well. Experiment 2, A2B1C2: 35CrMo steel pipe is used as the filter element material, the main pipe wall thickness of the filter element is 3mm, and the number of water holes is 800. After 20 days of field application, the pressure difference between the inlet and outlet was 1.5MPa: the filter element was taken out of the filter and the middle part was slightly deformed. Before replacing the filter element, use an ultrasonic flowmeter to measure the flow rate of 70m3/day, which did not meet the daily injection requirements of the well

Experiment 3, A1B2C2: The filter element material uses 45 steel pipes, the main tube wall thickness of the filter element is 5 ram, and the number of water holes is 800. After 20 days of field application, the inlet and outlet pressure gauges showed a pressure difference of 1.5 MPa; the filter element was removed from the filter and the middle part was slightly deformed. Before replacing the filter element, use an ultrasonic flowmeter to determine the water flow rate to be 70m3/Et, which did not meet the Et injection requirements of this well. Experiment 4, A2B2C1: The filter element material uses 35CrMo steel pipe, the main tube wall thickness of the filter element is 5ram, and the number of water holes is 1200. After 30 days of field application, the pressure difference was 1.5 MPa. The filter element was taken out from the filter and disassembled for inspection and found that the entire filter element was intact. The ultrasonic flowmeter was used to measure the amount of water passing to be 88m3/Et, which reached the Et injection requirement of the well.

Combining the above 4 experiments, we get the orthogonal experiment results shown in Table 3. Comparing the use time and the size of the numbers I and II, the factor rank II in the first and second columns is larger than I, indicating that the material factor 35CrMo pipe is better than 45 steel pipe. Wall thickness factor The main body thickness of the filter element is 5 ram thickness better than 3 ram thickness. The factor rank I in the third column is larger than that of Ⅱ, indicating that the number of water-passing holes is 1200 holes better than 800 holes. The size of the range is used to measure the effect of the corresponding factors in the experiment. The range of the first and second columns is R=12, which is the largest; the range of the third column is R=4, which is smaller than the range of the first and second columns=12 This shows that the material factor A and wall thickness factor B are the most important factors affecting the service time of the filter element, and the number of water holes is the secondary factor affecting the service time of the filter element.

In summary, through orthogonal experiments, the implementation results of No. 4 test plan show that: the filter element has no deformation after 30 days of use, and the time is the longest; the amount of water passing also meets the injection requirements. This scheme is a better scheme (see Table 3). See Figure 3 for the improved filter element.