Polymer configuration control system scheme of the

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Oil field polymer configuration control system scheme

1. Scheme Description:

the important means of realizing the third oil recovery in the oil field is the oil extraction method of polymer injection. The process is to mix the polymer and water in a certain proportion in the preparation station, and after a certain period of maturation, it is transported to each injection station through the export pump, diluted with clean water in the injection station, and then injected into the well. At present, the "centralized preparation and decentralized injection" polymer dispensing system is promoted, that is, one polymer dispensing station corresponds to multiple injection stations

at present, the control of preparation and injection is relatively independent, and there is no control system connecting preparation and injection. Due to the vast area of the oil field, it is very difficult to achieve stable and effective centralized control. Moreover, the distance between stations is far, and it is impossible to use conventional control. By using the built-in control algorithm of force control software and using the radio remote communication components, a coordinated and unified control system of preparation station and injection station is established

II. Polymer configuration

2.1 process overview

according to the needs of tertiary oil recovery, a large number of gelled polymer configuration systems are used in oil production operation areas. The system can be divided into two parts, namely, the dispersion of polymer and the maturation of polymer solution. The dispersing device plays an important role in the whole system. Its function is to mix the dry powdered polymer with water through proportioning and stirring, so that it can be mixed into a uniform solution that meets the concentration requirements. Because the polymer solution requires high concentration accuracy, and the polymer is easy to produce "fish beads" and "Stickiness" when encountering water, this part should be fully automated by the computer. Moreover, the device can also be made into a mobile vehicle mounted form. The ripening system is mainly completed in the field ripening tank, and the control form of this part can be manual or computer

(1) decentralized part: the control process is as follows:

after supplying 0.4-0.5mpa pressure water, dry powder and electricity (220V, 380V). This part can automatically produce the solution according to the required solution concentration (the concentration can be adjusted), and the error is less than ± 5%. The clean water is pumped by the clean water pump, and the polymer is sent by the polymer tank through the blower jet. The clean water and polymer are mixed in the mixer and enter the mixing tank. After mixing, they produce the required solution, and then the local curing tank is pumped by the liquid transfer pump. So far, the whole decentralized process of configuration has been completed

(2) put an end to the aging part of VOC exceeding the standard: the control process is briefly described as follows:

the polymer solution configured by the dispersion device is pumped into three aging tanks through the liquid transfer pump. In the aging tank, the solution formed by stirring for more than 120 minutes can meet the use standard. It is pumped out by the export pump and sent to each injection station

2.2 control scheme:

the logic and sequence control part of this scheme is completed by PLC, and the picture monitoring of the whole control process is completed by the force control monitoring software. The whole control system is divided into two parts: long-term favorable PCB manufacturers, decentralized PCB enterprises, serious product homogenization, decentralized and mature. Two subroutines can be formed in PLC and called on demand. The picture monitoring can also be divided into two parts, which are displayed separately

III. control screen function:

1. Screen monitoring: including process monitoring screen, process parameter display, alarm screen, trend screen and report screen

2. Manual/automatic switching. Any part can be controlled manually without affecting the automatic process of other parts

3. Input prompt, support the working mode of touch screen, and soft keyboard appears wherever there is input

4. Formula management can be carried out, and the operator can adjust the proportion of solution according to needs

III. introduction to remote control of injection station:

generally, the oilfield polymer preparation station can be equipped with two injection stations, each of which has nineteen polymer injection pumps and a storage tank. There is a pressure transmitter on the mother liquor pipeline at the outlet of each polymer injection pump and the inlet of clean water, an electromagnetic flowmeter and a flow transmitter on the clean water pipeline

the control scheme of this computer monitoring system is to use industrial computers to replace the original manual control system. The injection station and the preparation station achieve linkage control, and the injection station fully achieves the computerization of monitoring and control. The control functions are shown below:

III. description of computer monitoring software:

1. Description of control algorithm:

because the injection volume and pump efficiency of 19 pumps in 1# injection station directly affect the 1# injection station storage tank. Although EPS and XPS are cheaper than Pu tank level changes, it is necessary to control the injection volume by adjusting the speed of the frequency converter in the configuration station, To maintain the liquid level of 1 × storage tank, and the principle of 2 × injection station is the same The difference is that the 2# injection station does not directly control the frequency converter, but directly controls the regulating valve.

when the flow of the control valve cannot meet the requirements, fine tune the frequency converter, and the control algorithm adopts advanced control algorithm

target volume: liquid level of storage tank in 1# and 2# injection station

control quantity: configure the speed of frequency converter in the station and the adjustment quantity to 2# injection station

disturbance: flow change of each injection station

according to the current actual situation, it is impossible to achieve the stability of the liquid level of two storage tanks by using the conventional PID control algorithm. It is necessary to adopt the advanced control algorithm to achieve the stability of the two liquid levels

2. Description of monitoring operation software:

a. user process screen function

truly reflects the process flow on the process screen, which has a real-time, three-dimensional and dynamic effect. This screen not only has the function of directly displaying the liquid level, volume and weight of each tank farm, but also has the function of dynamic medium flow direction and various alarm functions

b. group picture function

each group picture can directly display the process status of 8 instrument circuits and visually represent it in the form of bar chart

c. trend screen

each liquid level has the function of historical trend and real-time trend. The maximum historical trend can reach 350 hours, and the operator can find it at any time according to requirements

d. voice alarm

it has voice alarm function for important production data. When the parameter reaches the high limit alarm or the low limit alarm, the voice is directly output to remind the operator to pay attention

e. process record printing

various required reports and records can be printed according to the requirements of the process workshop

f. database opening function

g, with WWW network to adopt typical materials used in the automotive industry (mainly PA family material access function, browser used in departments)

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