The rock is made into thin sections and placed in a hot and cold table, which is then placed under a microscope. Control the temperature rise and fall of the cooling and heating table. The formation temperature of gas-liquid inclusions was determined by homogenization method, and the freezing point of brine solution was determined by freezing method.
1.1 Principle of homogenization method
Selection of gas-liquid two-phase inclusions (single-phase inclusions when trapped).When heated to a certain temperature, the gas-liquid two-phase changes into one phase, and the phase state of inclusion formation is restored. The instantaneous temperature of phase recovery is the homogenization temperature of the inclusion.
1.2 Principle of freezing method：
The freezing point TM of the fluid phase is measured. Based on the principle that different concentrations of brine solutions have different freezing points, the liquid phase salinity of inclusions can be obtained by using the corresponding phase diagram according to the freezing points of inclusions.The inclusion of NaCl-H2O solution is usually expressed by the corresponding percentage concentration of NaCl solution, i.e. wi (NaCl).The salinity of inclusions can be calculated by the following formula:
Wi（NaCl）= -1.76958D – 0.042384D2 – 0.00052778D3
Where:
Wi（NaCl）—It is equivalent to the percentage concentration of NaCl solution, i.e. salinity, dimensionless
D—Freezing point, in centigrade (℃).
2.1 Fluorescence microscope: with long focal length objective lens, purple-ultraviolet fluorescence system and blue fluorescence system.
2.2 Hot table: the highest temperature should not be lower than 300℃, resolution 1℃
2.3 Cold station: temperature should be below -100℃, resolution 0.2℃
2.4 Calibration standard: the standard samples of substances or inclusions shall be analytically pure and above. The melting points of several commonly used compounds are shown in Table A.1. Inclusion standard sample temperature refers to the temperature value given by the manufacturing unit.
3.1 Sampling: Slice according to sample delivery requirements.
3.2 Cementing: use “502” or “501” glue for cementing
3.3 ground plane
3.4 Flat polishing: the polished flat rock sample is polished on the polishing machine with polishing fluid until the flat surface is as bright as a mirror
3.5 Adhesive sheets: Solid fir adhesive sheets, or “501” or “502” adhesive sheets.
3.6 Grinding: The rock sample glued on the loading plate is coarsely ground with no. 100 and no. 120 emery mixed with water on the grinding machine, and then with No. 280 and W20 emery mixed with water on the grinding machine step by step, and finally with W10, W7 and W5 emery mixed with water on the glass plate. When the particle size of rock minerals is greater than 2mm, the thickness of thin sections should be 0.1mm~1mm; When the grain size of rock minerals is less than or equal to 2mm, the thickness of thin sections should be 0.05mm~0.1mm
3.7 Wafer polishing
3.8 Dissolution of rock flakes: Slowly warm the rock flakes to be dissolved on an alcohol lamp, gently push the rock flakes to one end of the slide with medical tweezers, slowly remove them, put them into a beaker filled with alcohol, gently brush the rock flakes with a brush, and then remove the flakes; Use “501”, “502” adhesive rock slices and acetone bubble.
According to the genetic classification: inherited inclusion, diagenetic fluid inclusion
Classification by composition: brine inclusions, hydrocarbon inclusions
They are classified by phase: single-phase fluid inclusions (pure gas inclusions, pure liquid inclusions, solid inclusions), two-phase inclusions and multiphase inclusions
5.1 Microscopic characteristics of fluid inclusions
(1) Description of mineral characteristics
(2) release characteristics, morphology, size and abundance of fluid inclusions
(3) phase state, composition, gas-liquid ratio and type of fluid inclusion
(4) Color, phase and fluorescence characteristics of hydrocarbon inclusions
(5) The stages of hydrocarbon inclusions
(6) GOI and EGOI of hydrocarbon inclusions
(7) Epigenetic changes of inclusions
5.2 Determination of brine inclusion associated with hydrocarbon inclusion
5.3 Selection of inclusion for temperature measurement
6.1 Calibration of cold and hot table
6.1.1 Correction of hot table
If the standard sample temperature error is less than ±1℃, no correction will be made. If the standard sample temperature error is more than ±1℃, the temperature of the hot table shall be corrected
6.1.2 Calibration of freezing point of cold platform
If the standard freezing point error is less than ±0.2℃, no correction will be made. If the standard freezing point error is more than ±0.2℃, the cooling station temperature shall be corrected
6.2 Determination of homogenization temperature
The thin section of inclusion was placed in the hot table, and the microscope was adjusted to focus to find the desired inclusion. The heating rate was controlled between 3℃/min and 10℃/min, and the heating rate was less than 2℃/min when the inclusion was nearly uniform. The temperature at which the gas or liquid phase of the fluid inclusion disappears is observed. Repeat the operation for two or three times, take the average, and fill in the measurement record.
6.3 Freezing point determination
The temperature of the cooling and heating table was cooled until the inclusion was completely frozen, and then the temperature gradually rose. Before the last ice crystal disappeared, the heating rate was reduced to 0.5℃/min~1.0℃/min. The temperature when the last ice crystal disappeared was recorded, that is, the freezing point. Repeat the operation for two or three times, take the average reading, and fill in the measurement record.
6.4 Determination of the initial melting point
The temperature of the cooling and heating table was cooled until the inclusions were completely frozen, and then the temperature gradually rose. When the heating rate was reduced to 0.5℃/min~1.0℃/min, the temperature at the beginning of melting of the ice crystals in the inclusions was recorded, namely, the initial melting point. Repeat the operation for two or three times, take the average reading, and fill in the measurement record.
7.1 Quality requirements for instrument calibration
The instrument should be calibrated at least once a year. After the instrument is moved, it needs to be calibrated. When calibration with standard sample, the same standard sample should be selected for each calibration.
7.2 Homogenization temperature quality requirements
The absolute deviation of homogenization temperature measured parallel to inclusions should not be more than 2℃
7.3 Freezing point quality requirements
The absolute deviation of freezing point measured in parallel with the same inclusion should not be more than 0.2℃
SY/T6010-2011 Test method for fluid inclusion in sedimentary basins by microthermometry