CN-121992064-A - Method for evaluating under-scale sterilization effect of bactericide

CN121992064ACN 121992064 ACN121992064 ACN 121992064ACN-121992064-A

Abstract

The invention discloses a method for evaluating the under-scale sterilization effect of a bactericide, which comprises the steps of culturing SRB bacteria in a water body and under-scale in a closed environment, removing a film by an electrolytic method, removing a surface covering of a metal sample, and further obtaining a solution with the under-scale SRB bacteria, thereby evaluating the content of the under-scale SRB bacteria. The method combines the measured values of the bacterial content of the water body and the under-scale SRB before and after the bactericide is added, calculates and obtains the sterilizing effect (sterilizing rate) of the bactericide under the water body and the under-scale SRB, fills the defect that the traditional evaluation method cannot detect the bacterial content under-scale and cannot evaluate the performance of the bactericide under-scale, and has important popularization value.

Inventors

GUO LIANG
ZHANG JIANQIANG
LIN HAI
HUANG CHAO
CHEN XIAORONG
CHEN PING
XU JUN
XUE YAN
ZHANG XINRAN
SU YONG

Assignees

中国石油天然气集团有限公司
中国石油集团川庆钻探工程有限公司

Dates

Publication Date: 20260508
Application Date: 20241105

Claims (10)

1. The method for evaluating the under-scale sterilization effect of the bactericide is characterized by comprising the following steps of: S1, forming a scale cover layer on the surface of a metal sample by adopting an electrochemical cathode polarization pre-scaling method; S2, preparing an anaerobic solution with sulfate reducing bacteria, wherein the concentration of the sulfate reducing bacteria in the anaerobic solution is more than or equal to 100/mL; s3, placing the metal sample in the step S1 into the anaerobic solution in the step S2, hermetically soaking for 3-5 hours at the soaking temperature of 35 ℃ plus or minus 1 ℃, and detecting the concentration of sulfate reducing bacteria in the water body when no bactericide is added; S4, adding a bactericide into the solution for sterilization after the soaking in the step S3 is completed, and detecting the concentration of the sulfate reducing bacteria in the water body after the bactericide is added; S5, respectively placing the metal sample soaked in the step S3 and the metal sample sterilized in the step S4 into an anaerobic sealed electrolytic cell, removing the film by adopting an electrolytic method, respectively carrying out ultrasonic treatment on the solution after the film removal for 3-8min, detecting the concentration of the under-scale sulfate reducing bacteria when the bactericide is not added, and detecting the concentration of the under-scale sulfate reducing bacteria after the bactericide is added; S6, calculating the concentration of the sulfate reducing bacteria detected in the steps S3-S5 to obtain the sterilization rate of the bactericide under the water body and scale.
2. The method for evaluating the under-scale sterilization effect of a bactericide according to claim 1, wherein in the step S1, the electrochemical cathodic polarization pre-scaling method is performed in a simulation solution which is manually configured and is a mixed solution of 0.5-1 g/L Ca (NO 3 ) 2 and 0.5-1 g/L NaHCO 3 ).
3. The method for evaluating the under-scale sterilization effect of a bactericide according to claim 2, wherein 100-1000 sulfate-reducing bacteria per ml of the simulated solution are added.
4. The method for evaluating an under-scale sterilization effect of a bactericide according to claim 1, wherein in the step S1, the electrochemical cathodic polarization pre-scaling method is a three-electrode method, and a cathodic potential of-1.0V is applied to the surface of the working electrode.
5. The method for evaluating an under-scale sterilization effect of a bactericide according to claim 1, wherein in the step S1, the time for pre-scaling by electrochemical cathodic polarization is 5-8 hours.
6. The method for evaluating an under-scale sterilization effect of a bactericide according to claim 1, wherein in the step S2, the anaerobic solution is a NaCl solution with a mass concentration of 1.5-3.5% according to the water quality configuration of the on-site stratum.
7. The method for evaluating the sterilizing effect under the scale of the bactericide, which is characterized in that a graphite or platinum anode is adopted for electrolytic membrane removal, a metal sample with scale after soaking is taken as a cathode, the current density of the cathode is 100A/m < 2>, and the membrane removal time is 5 minutes.
8. The method for evaluating the under-scale sterilization effect of a bactericide according to claim 1, wherein in the step S5, electrolytic film removal is performed in an anaerobic ammonium citrate solution, and the ratio (V/S) of the amount V (mL) of the ammonium citrate solution to the exposed area S (cm 2 ) of the metal sample with scale is more than 20 mL/cm 2 .
9. The method for evaluating an under-scale sterilization effect of a bactericide according to claim 1, wherein in the step S6, the sterilization rate of the bactericide in the water body is calculated as follows: wherein E s is the sterilization rate (%) of the bactericide to the sulfate reducing bacteria in the water body, C s0 is the concentration ((in/mL) of the sulfate reducing bacteria in the water body when the bactericide is not added, and C s1 is the concentration (in/mL) of the sulfate reducing bacteria in the water body after the bactericide is added.
10. The method for evaluating the under-scale sterilization effect of a bactericide according to claim 1, wherein the under-scale sterilization effect (sterilization rate) of the bactericide is calculated as follows: Wherein E d is the sterilization rate (%) of the bactericide to the under-scale sulfate reducing bacteria, C d0 is the concentration (in/mL) of the under-scale sulfate reducing bacteria when the bactericide is not added, and C d1 is the concentration (in/mL) of the under-scale sulfate reducing bacteria after the bactericide is added.

Description

Method for evaluating under-scale sterilization effect of bactericide Technical Field The invention relates to the technical field of oilfield development, in particular to a method for evaluating the under-scale sterilization effect of a bactericide. Background In oilfield production, various microorganisms such as Sulfate Reducing Bacteria (SRB), saprophytes (TGB), iron Bacteria (IB), sulfur bacteria, yeasts, algae, protozoa, and the like are commonly present. These bacteria can cause metal corrosion, formation plugging, and deterioration of chemicals. Among them, sulfate reducing bacteria are the most harmful, and 70% of U.S. oil well corrosion is reported to be caused by sulfate reducing bacteria. The current indoor evaluation method of the performance of the bactericide in the petroleum and natural gas industry is based on SY-T5890-93 'method for evaluating the performance of the bactericide', however, the standard can only detect the bactericidal performance of the bactericide in water, and cannot effectively evaluate whether the bactericide can penetrate a scale layer or not and whether the bactericide has a bactericidal effect on bacteria under the scale. Industrial piping, vessels, and other related equipment are often susceptible to bacterial growth during operation. Especially in the production process of oil and gas fields, complex sediments generated in the process are attached to the surface of metal, so that a scale-down closed environment is easy to form, and bacteria are further caused to grow. Particularly, the breeding of Sulfate Reducing Bacteria (SRB) can lead to serious under-scale corrosion and massive H2S release, and seriously affect the safe production. The traditional SRB detection and bactericide evaluation mainly aims at SRB bacteria in water, and the SRB detection and bactericide evaluation of the under-scale environment cannot be considered. Therefore, a series of problems such as incomplete SRB killing, shortened dosing period, increased under-scale corrosion and the like can be caused. Therefore, the method for effectively detecting the under-scale SRB content and evaluating the sterilization effect of the under-scale bactericide has important engineering practical value. However, the prior detection of the under-scale sulfate reducing bacteria and the evaluation of the under-scale bactericides have defects or shortcomings, which are mainly reflected in that a reliable under-scale sulfate reducing bacteria evaluation method cannot be established, and the detection of the under-scale SRB content and the sterilization effect of the under-scale bactericides lack corresponding evaluation methods. Disclosure of Invention The invention aims to provide an evaluation method of the under-scale sterilization effect of a bactericide, which comprises the steps of manually simulating an under-scale environment, culturing SRB bacteria in a water body and under-scale in a closed environment, removing a film by an electrolytic method, removing a surface covering of a metal sample, and further obtaining a solution with the under-scale SRB bacteria, thereby evaluating the content of the under-scale SRB bacteria. The method combines the measured values of the bacterial content of the water body and the under-scale SRB before and after the bactericide is added, calculates and obtains the sterilizing effect (sterilizing rate) of the bactericide under the water body and the under-scale SRB, fills the defect that the traditional evaluation method cannot detect the bacterial content under-scale and cannot evaluate the performance of the bactericide under-scale, and has important popularization value. In order to achieve the above object, the present invention has the following technical scheme: S1, forming a scale cover layer on the surface of a metal sample by adopting an electrochemical cathode polarization pre-scaling method; S2, preparing an anaerobic solution with sulfate reducing bacteria, wherein the concentration of the sulfate reducing bacteria in the anaerobic solution is more than or equal to 100/mL; s3, placing the metal sample in the step S1 into the anaerobic solution in the step S2, sealing and soaking for 3-5 hours, wherein the soaking temperature is 35 ℃ plus or minus 1 ℃, and detecting the concentration of sulfate reducing bacteria in the soaked solution; s4, adding a bactericide into the solution for sterilization after the soaking in the step S3 is completed, and detecting the concentration of the sulfate reducing bacteria in the water body after the bactericide is added; S5, respectively placing the metal sample soaked in the step S3 and the metal sample sterilized in the step S4 into an anaerobic sealed electrolytic cell, removing the film by adopting an electrolytic method, respectively carrying out ultrasonic treatment on the solution after the film removal for 3-8min, detecting the concentration of the sulfate reducing bacteria under the scale when the bactericide is not ad