I. Overview.
Oilfield joint station existing injection pump, Taiwan Taiwan standby.
As of deadline, the cumulative operation hours of the water injection pump ( pump pipe) all surpass that of "Taiwan has approached 10000. Although it has been repaired many times, the prospect of using the pump is not optimistic from the overall operation of the pump. First, the water suction pressure Higher, about pump pressure, the moment may exceed the rated pressure of the pump, the pump operation is always in high load condition; second injection of sewage, poor water quality, strong corrosive, high water temperature, likely to cause the valve body , Pump head, packing assembly and other vulnerable parts of the damage, so that the pump in a high opportunity to damage the state; Third maintenance personnel regular maintenance, replacement parts, the pump is not in a continuous working condition.
Pump running status does exist some worries, to analyze the causes of some common pump failures, and to make timely diagnosis and monitoring diagnosis system to make judgments and prevention, both from a security point of view or from the economic aspects are particularly important.
Second, injection pump condition analysis. .
The basic structure is: the crankshaft, connecting rod, crosshead and other components of the power end; by the pump head, pump valve, plunger and seal device composed of hydraulic end, in addition to columnar, spherical nitrogen regulator and safety valve. The hydraulic end of the horizontal straight through the combination of the overall structure of the pump head.
Work, when the plunger moves backward, the outlet valve is closed, while the suction valve is open, start absorbing process; When the plunger forward movement, the suction valve is closed, the valve is opened at the same time. This cycle, continue to absorb water, drainage. . Water Pump Overview.
Since the pump was put into operation, with the increase of running time, the aging of various components one after another, the original working conditions have undergone great changes.
First of all, as the development of the oilfield requires the continuous improvement of water injection strength, the pump pressure is also on the rise. At present, some of the operating pressures have reached or exceeded the rated pressure of the water injection pump. For these overpressure operation of the water pump easily lead to equipment safety incidents.
Secondly, fatigue damage may occur to the moving parts of the water injection pump. Because the water injection pump belongs to the reciprocating piston pump, the five crankshaft connecting rod shoes and the crankshaft bearing cyclical heavy load act as the number of operating hours increases. Easy to appear off pieces, crankshaft journal wear and so on.
Again, the water pump increases the gap between the movement, due to long hours of operation, the crosshead and crosshead copper sleeve, connecting rod tile and small head tile will exacerbate wear and tear, increased gap leading to increased pump vibration, oil temperature, Pump operation noise is also significantly increased. The current crankcase oil temperature has risen to around.
Third, the impact of sewage water quality on the pump.
Sewage, which is separated from the crude oil during dehydration, is separated by oil-water separation, deoxygenated and de-treated, and then injected into the oil layer. Although treated to a certain extent, the injected water is still oil-bearing (polymer) sewage, which is generally alkaline, has low hardness, low iron content, high salinity and low water quality compliance rate. Due to the repeated use of sewage, Its suspended solids, artificial additives, etc. will be relatively high, widespread corrosion, scaling and plugging and other issues, of which the greatest damage to corrosion.
Combined with the special geographical environment of the oilfield (saline-alkali and marsh area), reservoir characteristics (low-porosity and low-permeability condensate reservoir) and characteristics of output fluids (high salinity), various metal pipelines and equipment Corrosion is more serious, especially the joint station oily sewage treatment system corrosion is more prominent, put into operation two months on the emergence of equipment corrosion perforation, seriously affected the normal production.
Water quality on the injection pump parts corrosion.
When the water injection pump is used to transport the sewage medium, the minerals and additives therein tend to precipitate on the sealing device, reducing the sealing effect. The solid particles also cause excessive wear to the sealing device, increasing the leakage of the water injection pump and shortening the service life. Therefore, the quality of sewage water is the main reason for the failure of the plunger pump seal.
From the pump room operation shows that the injection of water two pumps are particularly serious corrosion, not only for the pump itself, the water quality will also corrode other water injection facilities, such as the pipeline connected to the perforated phenomenon.
Corrosion reason can be attributed to the following aspects.
(1) Dissolved Oxygen In highly salinized water, dissolved oxygen plays a role of cathode depolarization during the corrosion process, which intensifies the corrosion of the steel by the wastewater.
(") Sulfate-reducing bacteria and hydrogen sulphide wastewater contain large amounts of sulfate-reducing bacteria, which have a significant impact on the local corrosion of steel.
(3) When the content of suspended solids and oily oil is large, they stick together and adsorb and deposit on the inner wall of the system, resulting in conditions that are more conducive to the growth and reproduction of sulfate-reducing bacteria. At the same time the dirt will increase the adsorption of germicides, bactericidal effect worse, to promote bacterial corrosion. Dirt deposition on the steel surface, the lower the potential to become the anode, in the absence of dirt at the cathode, the formation of scale corrosion.
Field often use infrared temperature detector on the pump hydraulic cylinder temperature detection, and the injection of sewage pump prone to over-temperature conditions, because the sewage itself is too hot, the heat is large, if the heat is not easy to cause packing and packing Abnormal wear between the plunger to speed up the packing replacement frequency; but also lead to a gradual increase in oil injection pressure, resulting in increased water injection energy consumption.
Fourth, water pump common fault analysis and solutions.
Cylinder temperature rise and solution.
Cylinder temperature increase is a common failure of the power side, as mentioned earlier, crankcase oil temperature has been greatly increased. Mainly due to the increase in water pump operating hours, the various parts of the cyclical cyclical load caused by serious, there are: Bearing serious wear and tear, crankshaft wear, lubricant emulsification or viscosity decline, the power side of the phenomenon of partial wear (such as crank limp Grinding), even more serious changes in trajectory connecting rod, crankshaft fixed bearing wear and so on.
In addition, when the pump valve loosening phenomenon, some components may fall into the pump cylinder, which will result in decreased sealing performance. Seal failure (usually packing damage), connecting rod serious leakage of thorns, the seal must be replaced immediately. Otherwise, the water will enter the crankcase along the connecting rod to emulsify the oil, resulting in severe damage to the power end (especially the crankshaft) and even the entire pump in a short time.
As the crosshead in the slide constantly back and forth movement, prone to the slide injury, etc., in serious cases will cause the pump shell scrapped, even if it can be repaired, because this type of pump is the integration of the pump casing Design, so the repair is equal to the entire pump overhaul. It is understood that the station has been scrapped - a pump casing (each value & million multivariate), and to be overhaul to be shipped to Dagang Oilfield, freight, maintenance costs and other costs are quite high. The solution is to promptly replace parts, lubricants and calibration.
Reasons and Analysis of Leakage of Sealing Packing.
Water pump plunger seal more use of soft asbestos packing for sealing, on the one hand these types of materials easily damaged, such as the above-mentioned water quality causes packing corrosion or even need to constantly replace the packing; On the other hand due to the high pressure medium in the delivery state, the abnormal plunger movement will lead to uneven packing force, resulting in the phenomenon of media leakage; In addition, the packing box gland due to running too long will appear too loose Phenomenon, resulting in seal leakage.
The solution is to repeatedly replace the packing when the final shape; in order to prevent uneven force, pressure and pressure required, and measured with a torque wrench; routine maintenance need to adjust the gland tightness.
two. Plunger seal failure reasons.
Due to the long service life of water injection pumps and poor weather conditions in the oil zone, as well as serious water erosion on the plunger, many grooves and pitting points that can not be seen by the naked eye are gradually formed on the surface of the plunger. Xu More tiny waterways. The minor erosion of the plunger surface and the failure of the packing are the main causes of the plunger seal leakage. The aqueous medium also drips into the piston chamber through the plunger seal under the effect of internal high pressure.
In addition, the scaling will have an impact on the seal, the sewage contains calcium and magnesium ions and carbonate ions, easy to produce carbonated scale. When the plunger pump is out of service, there is sewage between the plunger and the seal. When the water evaporates, crystals are precipitated. When the plunger is replaced or overhauled, white crystals are attached on the surface, which will cause the plunger pump to run Hard wear, resulting in seal failure.
Reasons and Analysis of Pump and Pipe Vibration.
From the scene of the pump operation point of view, the vibration of the pump body is more serious, feel more strongly by hand touch the pipeline, observe the installation of thermometers and other instruments on the pump body is also in an unstable state, buried pump line cement floor also Cracks and reinforced several times, and then the site of high-intensity noise and vibration over a great relationship and so on.
After investigation and analysis, the general reasons are summarized as follows.
(1) Foundation is not strong.
(2) A large cylinder or a few large hydraulic losses, resulting in uneven pressure on the pump head.
(3) crankshaft axial movement.
(4) Plunger connection clip loose.
(5) crankcase internal failure and so on.
summary.
Pump in operation, in addition to wearing parts need to replace the normal wear and tear repair, the most important is to avoid the internal crankcase failure, this failure may cause burning tile, pulling cylinder phenomenon, resulting in equipment operation accident, resulting in serious Equipment completely scrapped. The reasons for burning tiles are many, there are: the viscosity of oil failed to meet the requirements; the presence of impurities in the oil; emulsified oil and other water. Of course, crankshaft and bush clearance is too large or too small; crankshaft axial bearing clearance is too large or too small; connecting rod deformation, etc., may also cause internal crankcase failure.
The significance of failure analysis.
Because of water pump failure accident occurred, such as causing power plant blackouts and water fall (caused by the pressure drop), the loss of millions. At present, the danger can only be avoided by prompt repairs based on the abnormal changes of the motor and pump, but at this time a lot of losses have been caused. Pump damage after the overhaul costs, transportation costs, such as a large number of pump parts replacement will affect the production lead to more economic losses.
After rough statistics, the annual comprehensive maintenance cost of each pump is about RMB10,000, while overhauls cause stoppages about every day in Taiwan, less oil production, about RMB or so, and may cause other situations such as water blockage.
Research on the fault diagnosis of water injection pump is of great practical significance, both to ensure the safe operation of equipment, to avoid causing serious accidents, to ensure the safety of workers; at the same time from the economic point of view, can greatly save a variety of maintenance costs .
Sixth, the conclusion.
In order to better exploit existing underground oil storage and ensure Nissan's oil production, it is necessary to ensure the long-term, safe, reliable and efficient operation of water injection station equipment. Therefore, it is very important to analyze the failure of the water injection pump at the water filling station and to adopt the on-site monitoring technology to realize the modern equipment management, improve the production efficiency and ensure the normal operation of the equipment. At the same time, it is the only way to realize the modern management of water injection equipment for water injection station through fault diagnosis, promptly reporting the operation status of water injection pumps, preventing accidental accidents and ensuring daily water injection.