SY/T 5253-1991 Natural gamma ray spectrum analysis method for rock cores High purity germanium detector method SY/T5253-1991 standard download decompression password: www.bzxz.net

Petroleum and Natural Gas Industry Standard of the People's Republic of China SY / T 5253-91
Natural Gamma Spectroscopy Analysis Method for Rock Cores
High Purity Germanium Detector Method
1991-07-19 Issued
Ministry of Energy of the People's Republic of China
1991-11-01 Implementation
1 Subject Content and Scope of Application
Petroleum and Natural Gas Industry Standard of the People's Republic of China Natural Gamma Spectroscopy Analysis Method for Rock Cores
High Purity Detector Method
SY / T 5253- -91
This standard specifies the measurement time, steps and analysis error requirements for samples when using high purity germanium detectors for natural gamma spectroscopy analysis of rock cores.
This standard is applicable to the analysis of natural gamma spectroscopy characteristics of rock cores using high purity germanium detectors. 2 Basic method of measurement using high-purity germanium detectors Crush the core and grind it into 100-200 grams of powder. Take the same volume of the powder as the standard sample and put it into the sample box. Seal it for 28 days and place it in a low-background lead chamber for energy spectrum measurement. Then print out the measurement results in a data table or energy spectrum diagram. According to the peak area of ​​each characteristic energy peak of K, Th, U and CPS (counts/s), calculate the content of radioactive elements K, Th and U. 2.1. Measuring device
a. High-purity germanium detector:
b. Low-background lead chamber;
c. Spectral weight amplifier;
d. Multi-channel analyzer;
e. Computer and printer.
The system resolution is 1.9keV and the relative efficiency is 35%. For *K1460keV? The attenuation factor of the background radiation is 234 times, and the attenuation factor of the integrated background in the energy range of 40-2633keV is 90 times. 2.2 Supporting tools
a. Dewar flask
b. Crusher;
c. Grinder;
d. Electronic balance: maximum weight 1000g, accuracy 0.1ge Beaker-type plastic rock sample box: height 74mm, diameter 74mm. 2.3 Parameters of standard samples
Pure quartz sand with extremely weak radioactivity is crushed to 100-200g, and then dried and mixed with standard uranium powder and spectral pure KCl powder prepared by a special unit according to the specified proportion. Take 180cm of the above mixture and seal them into sample boxes respectively. Recommended parameters of standard samples: K content 8.74%: error 1%, mass 300g: Th content 203.33×10-, error 5%, mass 310g: U content 209.3×10-, error 5%, mass 320g. (Specific parameters depend on the actual situation in the region) 2.4 Preparation and processing of core samples
First crush and grind the sample into 100-200 "powder, dry and take the same volume of powder as the standard sample, weigh it and put it into the sample box, seal the box mouth, and measure it after 28 days. 2.5 Provisions on measurement time
2.5.1 Background measurement is 8h,
Approved by the Ministry of Energy of the People's Republic of China on July 19, 1991-07-19, implemented on November 1, 1991
2.5.2 Measurement time of standard samples
SY / T 525391
Depends on the error of the net area of ​​the main energy peak, and the error is required to be less than 1%. 2.5.3 Measurement time of core samples
Depends on the radioactive strength of the rock sample and the measurement accuracy. The net area of ​​the weakest main energy peak is required to be above 200 counts. 2.6 Linear scale of the measurement system
Before measuring the sample, use the standard sample to perform linear scale on the measurement system to determine the linear relationship between several main energy peaks and their addresses. The main energy peaks are 351.9, 583.1, 609.3, 911.0, 1120.4, 1460.7, 1764.5, 2614.5keV. 2.7 Steps for measuring core samples
2.7.1 Fill the Dewar flask of the detector with liquid nitrogen. 2.7.2 Perform linear scale of the system according to the provisions of 2.6. 2.7.3 Bias the detector to 2 500V, 2.7.4 40min after adding bias, measure background for 8h 2.7.5 Measure three standard samples of K, Th and LI respectively. The measurement time of each standard sample is shown in 2.5. 2.2.7.6 Measure the core sample. The measurement time is shown in 2.5.3. 2.8 Provisions for background measurement
Before measuring each batch of samples, the background must be measured once. Provisions for measuring standard samples
After each bottom measurement, the standard sample must be measured once. 2.10 Calculation and analysis of measurement results
2.10.1 According to the net area and CPS of each main energy peak of the background spectrum, standard sample spectrum and core sample spectrum, calculate the content of K, Th and U.
2.10.2 Use the following formula to calculate the content of the corresponding isotope of each main energy peak: D
Where:
(Cni-B,) /Wr
-Use the CPS of the (main energy peak of the jth parent nucleus system to calculate the content of the jth parent nucleus in the sample, 10~'; the content of the ith parent nucleus in the standard sample, 10-
sample mass:;
standard sample mass,
CPS of the ith energy peak of the ith parent nucleus system of the sample: CPS of the ith energy peak of the ith parent nucleus system in the standard sample CPS of the ith energy peak of the ith parent nucleus system in the background spectrum. The average value of the contents obtained from different energy peaks of the same isotope is calculated to obtain the content of this isotope. 2.11 Analysis error of rock samples
2.11,1 Analysis error formula:
G=Om—QR
Where:
Relative standard deviation;
Standard deviation:
x 100%
analyzed content of mixed standard sample;
SY /TS25391
R——actual content of mixed standard sample. According to the above formula, the K, Th and U contents obtained by measuring a mixed standard sample should meet the measurement tolerance compared with the actual content of the mixed standard sample.
2.11.2 Measurement allowable deviation
The allowable deviation of core sample analysis is shown in Table 1
Table 1 Allowable deviation of core sample analysis
Measurement range
>12 × 10 6
12 × 10~
>6× 10-6
6×[0~
2.11.3 Inspection standard of core sample analysis error
11×[0-
± 0.5 × 10*6bZxz.net
Relative standard deviation, %
In the process of measuring a batch of core samples, the mixed standard sample is measured three times at different times as the basis for checking the accuracy of the measurement system.
Additional remarks:
This standard is proposed and technically coordinated by the Oil Well Logging Professional Standardization Committee. This standard was drafted by the Institute of Well Logging Company of North China Petroleum Administration Bureau. The main drafter of this standard is Cheng Ling.
This standard is still valid after the review in 199, and the review result has been approved by the State Administration of Petroleum and Chemical Industry.
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