Method for increasing filtering speed of filter material

Abstract

The invention discloses a method for increasing the filtering speed of a filter material, wherein the method comprises the following steps: 1) firstly, adding strong oxidant gas into sewage to oxidize and decompose or / and crush a water-soluble polymer or / and polymer residue in the sewage so as to enhance the ability of the sewage to pass through the filter material; and 2) filtering the sewage by using the filter material so as to enable the sewage to reach the standard for reinjection. The method can effectively solve the problem that a water-soluble polymer and emulsified oil severely influence the filtering speed and filtering performance of the filtering material, can greatly reduce the dosage and operation cost of demulsification and dehydration and sewage treatment of the combination station, and can greatly reduce the sludge yield; and the method has the advantages of being easy to implement, safe, reliable, wide in application, easy to popularize and the like.

Description

technical field [0001] The invention relates to the fields of oil and gas production and / or water treatment, in particular to a method for increasing the filtration speed of a filter material. Background technique [0002] At present, a large amount of sewage generated in the process of crude oil exploration and production is usually treated by sedimentation (or air flotation), filtration and other methods, and then re-injected into the oil layer or formation; figure 1 As shown, the sewage treatment method can be summarized as follows: the water-containing crude oil (also known as production fluid) produced by oil well 100 enters the separation and dehydration device (also known as three-phase separator) through valve 101 and oil collection pipeline (also known as oil production pipeline) 102 ) 103; in the separation and dehydration device 103, the separated associated gas (also known as natural gas) enters the natural gas pipeline 104 for further processing, the separated c...

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Problems solved by technology

[0010] However, at present, after the water-soluble polymer flooding method is applied to the oil wells under the jurisdiction of the joint station, the polymer content of the sewage after removal is about 20mg / L, and the suspended solid content is as high as 360mg / L or more; although the four filter tanks used in the station The material is still the mixed filter material of quartz sand + walnut shell, and the backwashing intensity (i.e. backwashing water flow rate) is increased by 1.5 times, and the backwashing frequency (or frequency) is increased by 1 times (i.e., after filtering the sewage for 4 hours, it can be used after filtration. However, the suspended solids content of the sewage filtered by the filter tank is still as high as 70mg / L, and the suspended solids content of the reinjected sewage is still as high as 60mg / L, which has exceeded the water injection in clastic rock reservoirs. The water quality index and analysis method SY / T5329-2012" and Shenyang Oilfield stipulated that the water injection index is more than 30 times, which has led to a substantial increase in the pressure of the water injection system; moreover, the pressure difference between the inlet and outlet of the filter tank is higher than that of the oil well using the water-soluble polymer flooding method The amount of filtered water (i.e. the filtration rate) is more than 60% lower than that before the water-soluble polymer flooding method was applied to the oil well, and the amount of backwash water increased by more than 150% compared to the oil well before the water-soluble polymer flooding method; As a result, the joint station is currently unable to use the existing 4 filter tanks to meet the task of sewage filtration

[0011] 2. The method of soaking and washing the filter material with detergent or / and acid and alkali is ineffective, and cannot effectively solve the problem of slow filtration rate of the filter material and substandard water after filtration

[0013] In order to solve the problems of slow filtration speed, increased pressure difference, poor backwashing effect, and greatly reduced filtered water volume of the existing 4 filter tanks, the joint station conducted a production test of chemical cleaning of the filter material of the filter tanks. The results showed that: the washing After fully soaking and washing the mixed filter material of quartz sand + walnut shell, the suspended solids content of the filtered sewage is still greater than 30mg / L, and the filter material is mixed with detergent or / and There is no significant difference before acid and alkali soaking and washing, and none of them meet the water injection indicators stipulated in "Water Quality Indicators and Analysis Methods for Clastic Reservoir Injection SY / T5329-2012" and Shenyang Oilfield; moreover, the filter material uses detergent or / After soaking and washing with acid and alkali, there is no significant change (or improvement) in the pressure difference of the filter tank, the filtration rate of the filter material, the amount of filtered water, the amount of backwash water and the frequency of backwash

[0014] 3. This method cannot solve the problems of demulsification and dehydration of polymer-containing production fluid (or water-containing crude oil) and a large increase in the amount of sewage treatment chemicals, and cannot solve the problems of large amount of polymer-containing sewage sludge and frequent tank cleaning. The operating cost and oil production cost have increased significantly, which has led to a substantial increase in management workload and labor intensity, and increased the difficulty of environmental protection governance

[0017] But at present, after applying the water-soluble polymer flooding method to the oil wells under the jurisdiction of the joint station, the amount of demulsifier has doubled to more than 100 kg / day, and the amount of water purifier (cationic polyacrylamide) has reached 800 kg / day; A large amount of mud and mucus containing suspended solids are continuously formed at the bottom of the three-phase separator and water injection storage tank, and production must be stopped for cleaning every 6 months; the amount of sludge generated has increased several times to more than 15,000 cubic meters per year

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