China Library Classification. : TE626.3 file identification code: A 0 brief introduction the main oil production equipment at home and abroad are pumping unit, oil pump, sucker rod, electric submersible pump, various hydraulic pumps and gas lift equipment. Among them, the pumping unit was produced and used as early as 120 years ago, and it is still one of the two most commonly used ground lifting equipment in oilfield production.

Production status, classification and performance characteristics of 1 pumping units at home and abroad

There are more than 1 10,000 mechanical oil wells in the world, including more than 900,000 pumping wells, and the number is increasing year by year. The number of pumping units in China is about 1 10,000 units, with an annual increase of about 5,000 units.

The development of pumping units in China has a history of nearly 40 years. In 1950s, CKH imported conventional beam pumping units from the former Soviet Union, supplemented by repairs. In the 1960s and 1970s, conventional beam pumping units were manufactured on the basis of imitating the former Soviet Union, and 1975 formulated and improved the technical standards of domestic pumping units. Since 1980s, all pumping units have been made in China, which not only satisfies self-sufficiency, but also partially exports. During this period, the pumping unit technology has advanced by leaps and bounds, aiming at the world advanced level, adopting the American API standard equivalently or partially, and introducing the advanced technology of Ravdin company, making our pumping unit rank among the world advanced ranks and enter the international market.

There are 10 pumping unit manufacturers in China, and the product types have been diversified. There are 45 pumping units in 6 categories, but the beam pumping unit is still dominant. Every year, about 30 patents of pumping units are added, and more than one pumping unit 10 is newly trial-produced, which basically meets the needs of land oil field exploitation. Various new energy-saving beam pumping units, such as double donkey head pumping unit, front pumping unit, out-of-phase crank balance pumping unit, front gas balance pumping unit, lower barbell series energy-saving pumping unit, narrow V-belt transmission conventional pumping unit, etc., have been popularized and applied in various oilfields in China, and achieved remarkable economic benefits.

The manufacturing of pumping units abroad has been quite concentrated. For example, in the United States, since 1992, the main pumping unit manufacturers have either adopted the technology of Ravdin Company or become the subsidiaries of Ravdin Company, adopting unified technology for production, and their products are highly serialized and standardized. The general development direction of pumping unit is overload, long stroke and low stroke times; Automation and intelligence; Efficient and energy-saving; Strong adaptability; No beam, long stroke, large scale.

There are many new pumping units in the world. If the modern pumping units are divided into two categories according to the past classification methods, the technical development of modern pumping units can not be fully expressed. Reversing system and balance system are the main components of pumping units, so the classification and naming of pumping units should be based on the characteristics of these two parts and should also conform to the naming and classification habits of oil fields. The new classification method is:

The pumping unit (1) contains a walking beam, which is reversed by a connecting rod mechanism and the weight of the crank is balanced. It can be classified as a beam crank balance pumping unit, which is generally referred to as a beam pumping unit for short, but it cannot be interpreted as crank balance.

(2) For the balanced beam pumping unit, special instructions shall be given.

(3) If the pumping unit changes direction through some mechanism, the beam will become shorter or even disappear, and the donkey head will become round due to the large swing angle (greater than or close to 180 degrees). This kind of pumping unit generally adopts the balance mode of walking beam close to the suspension point, and the balance of donkey head is made into a whole with arc and evolved into a wheel-shaped part, which is called crown block. It is more appropriate to call this kind of pumping unit a beam-less pumping unit or a crown wheel pumping unit with a certain mechanism reversing.

(4) The motor-commutated pumping unit generally drives the suspension point to work through the drum-driven steel wire rope, which should be called the motor-commutated drum-type pumping unit.

(5) The pumping unit that drives the drum to rotate forward and backward through various devices (with switching) or mechanisms (without switching) and drives the suspension point to move up and down should be called mechanical reversing drum pumping unit.

(6) There are two kinds of control systems for pumping units: common electronic control and numerical control. Numerical control pumping unit is generally called numerical control pumping unit.

Composition and working principle of pumping unit

There are many kinds of beam pumping units, but their structural principles are the same. The pumping unit is mainly composed of beam-connecting rod-crank structure, deceleration device, power device and auxiliary device, as shown in figure 1.

1. base; 2. brackets; 3. Rope hanger; 4. Shantou; 5. Walking beam; 6. Beam bearing seat; 7. Cross beam; 8. Connecting rod; 9. Crank pin device; 10. Crank device; 1 1. reducer; 12. Brake safety device; 13. Brake device; 14. Motor; 15. junction box

The power machine provides power, and the high-speed rotation of the power machine is changed into the low-speed rotation of the crank of the pumping unit through the reducer, and the rotary motion is changed into the up-and-down reciprocating motion of the donkey head of the pumping unit through the crank connecting rod beam mechanism to drive the deep well pump to work.

3 Main lubrication parts of pumping unit and their lubrication performance requirements

Although the structure and performance parameters of various pumping units are different, the main lubrication parts and varieties are basically the same. The motor, tail bearing, connecting rod upper pin, crank pin, intermediate bearing, donkey head pin and braking system of pumping unit need grease lubrication. Lithium-based grease or synthetic lithium-based grease is generally used for lubrication.

Gear box is the key component of pumping unit, which is generally a simple three-axis (transmission shaft, intermediate shaft and output shaft) parallel two-stage deceleration structure. The gears in the gearbox are lubricated by oil bath splash, and the joint surface of the gearbox is coated with sealant to prevent splash oil from leaking. An oil tank (with an oil scraper) is installed between the left and right rotating gears and the gear box, and the joint surface of the gear box is provided with an oil tank to provide lubricating oil for each bearing. There is an inspection window above the box body, and there is a labyrinth ventilation cover on it. There are three plugs with different heights at the back of the box, the lower one is used to drain oil, and the upper two are used to check the height of oil level. Generally, medium-pressure and extreme-pressure industrial gear oils are used for lubrication.

For the control system of hydraulic pump and hydraulic pumping unit motor, hydraulic oil is generally used for lubrication.

The lubrication of the gearbox of pumping unit plays a vital role in the normal operation of pumping unit, so it has been paid more and more attention by various oil fields. However, the main oil-producing areas in China are located in the northern region, where Leng Xia is hot in winter, and the working environment of each oilfield is different. Therefore, the overall requirements for lubrication are slightly different. The general requirements of lubrication are good viscosity-temperature performance, wear resistance, thermal oxidation stability, rust resistance, emulsification resistance and water resistance.

Oxidation stability is required because the special gear oil for the reducer of pumping unit is constantly stirred during the working process and contacts with air, metal and impurities. It is easy to oxidize and deteriorate at high temperature; The requirement of low temperature performance is due to the large temperature difference of oil pumping units. In order to ensure the normal operation of equipment in winter, higher requirements are put forward for the low temperature performance of oil products. Extreme pressure wear resistance is the bearing capacity of gears, which is mainly related to the performance of lubricating oil additives besides the viscosity of lubricating oil. Corrosion resistance is due to the acidic substances produced by the oxidation of gear oil used in the reducer of pumping unit, which will corrode the gear. Under the action of water vapor produced by temperature difference change, the tooth surface and oil tank will be corroded and eroded, which will not only destroy the geometric characteristics and lubrication state of the gear, but also further deteriorate the oil. The water resistance is due to the fact that the pump unit works outdoors. If the equipment is not well sealed, it is easy to get water. The moisture in the oil will accelerate the corrosion of organic acids to metals in gear oil of pumping unit reducer, resulting in corrosion of mechanical equipment, poor emulsifying performance and hydrolysis of additives, which will seriously affect the quality of lubricating oil.

Although the overall level of oilfield equipment management is improving year by year, the oil-water management of equipment is gradually improving, but the design, manufacture, management and field use of crude, large and stupid equipment such as pumping units do not pay enough attention to lubrication. The main problems of pumping unit oil (reducer oil for pumping unit) are: the selection of reducer oil is not uniform, and most designers and manufacturers have no standards for the selection of reducer oil, which is mostly based on experience and user feedback information, resulting in confusion in oil use. Change the lubricating oil at will. Due to the neglect of the management of coarse, large and stupid equipment, the gearbox of pumping unit can rotate with more oil and less oil, and the gearbox of pumping unit can also use oil or water. There are 68 machine oil, regenerated machine oil, semi-fluid anti-theft grease and so on. This obviously increases the damage of the gearbox of the pumping unit. The phenomenon of untimely oil change, poor working conditions of pumping unit (continuous operation in the field), serious external pollution of equipment, emulsification and deterioration of gearbox lubricating oil, long-term use of liquid level decline, oil leakage or theft and no oil output. , causing huge losses to the oil field. Oil leakage from gearbox is a common problem of pumping unit, which not only wastes oil, but also affects normal production. It is of great significance to standardize the quality of pumping unit oil for oilfield to prolong the service life of pumping unit and ensure safe production.

Production and research of pumping unit oil

Pumping unit is one of the important equipment for crude oil exploitation. Working in the field all the year round, the environmental temperature difference changes greatly. Whether its operation is normal or not is directly related to the economic benefits and safe production of the oilfield. However, for a long time, there have been irregular and inconsistent oil use in oil fields. The quality of lubricating oil used is uneven. Some oil fields still use 46 # and 68 # machine oil or waste oil to lubricate the reducer of pumping unit. Due to improper lubrication of equipment, when the ambient temperature is low or the load changes in winter, the equipment can not be well lubricated and protected, resulting in equipment damage.

In 2007, Dalian Lubricating Oil Research and Development Center of China Petroleum conducted a simple investigation on the use of oil for pumping units in a large domestic oilfield, and found that the pumping units of different drilling teams used more than 10 varieties and more than 20 products with viscosity grades, such as gear oil, mechanical oil, vehicle gear oil, turbine oil, total loss system oil, engine oil, semi-fluid grease, etc., and the quality was uneven, which could not provide good protection for the pumping unit gearbox.

At present, there are about 654.38 million pumping units in China, and about 5,000 pumping units are added every year. According to the calculation that the gearbox oil tank of conventional pumping unit is about 654.38+0.60 ~ 200 L and the pumping unit oil is replaced once a year, the oil consumption of pumping unit is about 6.5438+0.8 million t/a.

Because there are relatively many structures and varieties of pumping units, and the main lubricating parts-gear boxes are also different, OEM manufacturers have different requirements for lubrication performance. In addition, the application unit of pumping unit-the corresponding unit of oil field has different equipment management for the reducer of pumping unit, which leads to different pumping oil used by different oil fields, oil production plants and even different well teams of an oil production plant. There are gear oil, mechanical oil, vehicle gear oil, turbine oil, total loss system oil, engine oil, semi-fluid grease and other products. And the quality is uneven, which can not guarantee that the gearbox of pumping unit is in good condition.

The research and development of pumping unit oil has been carried out in China, mainly in the related lubricating oil plants near the oil field, China Petroleum and China Petrochemical. Among them, the small lubricating oil plant near the oil field is superior in supply, but inferior in technology.

Yumen Oilfield Research Institute of Refining and Chemical Technology has developed a semi-fluid lubricant for pumping units, which is made of refined mineral oil and various additives, in view of the climatic characteristics that Yumen Oilfield is located in the northwest Hexi region, with a monthly average maximum temperature of 2 1℃ and a monthly average minimum temperature of-1.5℃. It is also a special gear lubricant, which has certain fluidity and better adhesion than ordinary lubricating oil, and has the advantages of impact load resistance, rust prevention, leakage prevention, cold resistance and easy start-up, and is widely used in gear boxes of oil pumping units in oil fields. Its products are relatively simple, which can not meet the lubrication of pumping units in domestic oil fields. Daqing Blackbird Co., Ltd. developed a semi-fluid lubricating grease pump oil with good low temperature performance, certain bearing capacity, anti-wear ability and anti-leakage according to the specific oil production technology and climatic conditions of Daqing Oilfield and Jilin Oilfield. However, its products still have some shortcomings, such as poor low temperature performance and relatively single viscosity variety. According to the climatic characteristics of Daqing and the lubrication requirements of pumping oil, the Quality, Safety and Environmental Protection Department of Daqing Oilfield Company put forward a pumping oil standard with a quality grade equivalent to CKB 100 but good low-temperature performance, but this quality standard can not be widely used in its oilfield. China Petrochemical Lubricating Oil Company has developed gear oil for pumping units with quality grade equivalent to CKC 100. This product has been applied in two different types of pumping unit gearboxes in Shengli Oilfield, which can meet the requirements of all-weather use of oilfield equipment. However, the low-temperature performance of its products can not meet the lubrication requirements of pumping units in northern oilfield in winter.

In 2007, Dalian Lubricant Research and Development Center of China Petroleum and the quality, safety and environmental protection departments of Daqing, Xinjiang and Changqing oilfields jointly established a project in the exploration department of the joint-stock company-Technical Conditions of Lubricating Oil for Pumping Units in Cold Areas (see table 1 and table 2). Mainly referring to the mechanical industry standard JB/T 883 1 Selection Method of Lubricating Oil for Industrial Closed Gear and some technical requirements of L-CKC viscosity grades 100, 150 and 220 in the national standard GB 5903 Industrial Closed Gear Oil, and according to the actual working conditions of pumping units, Proposed by the Standardization Technical Committee of Exploration and Production Specialty of China Petroleum and Natural Gas Co., Ltd., this standard stipulates the technical content, sampling, inspection method and judgment principle of lubricating oil for pumping unit reducer in cold areas, and is suitable for production, acceptance and quality inspection of lubricating oil for pumping unit reducer in cold areas of oil fields. The quality level is equivalent to CKC closed industrial gear oil, and its viscosity grade and low temperature performance can meet the performance requirements of pumping units in various oilfields in China.

The naming rules are as follows:

China Petroleum Dalian Lubricating Oil Research and Development Center adopts Class I and Class II base oils, and adds a pumping unit oil complex agent composed of complex antiwear agents, antiwear agents, rust inhibitors, metal passivators, antioxidants and other additives, which can prepare pumping units with different viscosity grades and different low-temperature properties that meet the Technical Requirements for Lubricating Oils for Pumping Units in Cold Regions (Q/SY1138-2008).

5 conclusion

Pumping unit is one of the main equipment to ensure oil field output. Due to the characteristics of field work, the lubrication performance of its equipment is very high. Special gear oil for pumping units with good oxidation stability, wear resistance, low temperature performance and water separation performance must be used to ensure equipment lubrication and effectively reduce equipment energy consumption.

China Petroleum Lubricant Company can produce a series of pumping unit oil products with different viscosity grades and low temperature performance, which can meet the lubrication requirements of pumping unit equipment in China petroleum and different domestic oilfields.

Date of receipt: 20 10-06-02.

About the author: Yuan Maoquan (1970-), male, engineer, 1992 graduated from the Department of Applied Chemistry of Liaoning University of Petrochemical Technology, majoring in industrial analysis. Now he is engaged in the sales and management of lubricating oil and has published many papers.