Composite brine drilling fluid solid phase content optical measurement device and measurement method

Abstract

The invention belongs to the technical field of drilling fluid measurement, and particularly provides an optical measurement device and measurement method for the solid phase content of composite brine drilling fluid, a multi-wavelength laser emits a light beam, the light beam passes through a sample test bench, a cuvette and a drilling fluid sample in the cuvette, and then enters a photoelectric detector; the photoelectric detector is used for measuring the transmission light intensity of the drilling fluid sample in the sample test bench, and the data acquisition display is used for acquiring and transmitting the transmission light intensity of the measured drilling fluid sample to SCOM calculation processing software of the computer; the problems that when an existing composite brine drilling fluid adopts a distillation method to measure the insoluble solid content, the measurement process is complex, distillation and titration experiments consume a long time, and the measurement error is large are solved. According to the method, the influence of precipitation of inorganic salt or organic salt in the distillation process on solid phase content measurement when the solid phase content of the composite brine drilling fluid is measured by a traditional distillation method is eliminated, the measurement process is simplified, the measurement time is shortened, and the measurement precision and the measurement efficiency are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling fluid measurement, and in particular relates to an optical measurement device and a measurement method for the solid phase content of a composite brine drilling fluid. Background Art

[0002] Composite brine drilling fluid (containing salts such as KCl, NaCl, composite salts and organic salts) has excellent rheological properties of inhibiting hydration and dispersion of shale and stabilizing it. It plays an important role in stabilizing the well wall and purifying the wellbore during the drilling of inclined and horizontal sections. It is a water-based drilling fluid system with wide applications.

[0003] At the same time, the solid content in the drilling fluid is closely related to the density, rheological properties, filter cake quality, lubrication ability, etc. of the drilling fluid. The increase in solid content will lead to the deterioration of the drilling fluid performance, which will in turn cause a decrease in the mechanical drilling rate, reduce the efficiency of wellbore cleaning, increase the risk of differential pressure sticking, cause reservoir damage and affect the production capacity of oil and gas wells. Therefore, it is necessary to measure and monitor the solid content of the drilling fluid at the drilling site to provide a basis for the fine-tuning of the drilling fluid performance.

[0004] However, when measuring the insoluble solid content of brine drilling fluid using the distillation method in GBT 16783.1-2014 Drilling Fluid Field Test Part 1: Water-based Drilling Fluid, the salts and insoluble solids remain in the distiller and cannot be separated. The above standard requires the measurement of Cl - Content, using Cl - The NaCl content in the brine drilling fluid can be obtained by calculating the solid content in the NaCl brine. + The ions will enter the clay mineral layers through ion exchange to inhibit their expansion and dispersion, making the K + Ion content is less than Cl - content, so through Cl - Errors will occur when calculating the KCl content and solid content. On the other hand, this method is only applicable to drilling fluids containing only one salt (NaCl or KCl), and is invalid for drilling fluids containing two or more salts. In addition, titration experiments are required to determine the ion concentration during the measurement process. The measurement process is complicated, and the distillation and titration experiments are time-consuming. In addition, some drilling fluids will spray out of the distiller during distillation and heating, which will cause certain measurement errors.

[0005] Therefore, it is urgent to develop a method and instrument that can quickly measure the solid content of drilling fluids containing a variety of salts (KCl, NaCl, etc.) to provide a decision-making basis for the refined maintenance and adjustment of on-site drilling fluid performance.

[0006] A Chinese patent document with publication number CN102305783A and publication date January 4, 2012 discloses a fiber laser Raman device for multi-parameter analysis of drilling fluid. The device can study the Raman spectrum response characteristics of hydrocarbons in drilling fluid according to the temperature and vibration conditions required by drilling detection, and analyze the influence of temperature and vibration on the spectrum. The fiber inverted microscopic laser Raman drilling fluid multi-parameter analysis device includes: four micro semiconductor lasers with wavelengths of 280nm, 428nm, 840nm and 1046nm (power> 50mw), a dye laser, a high-hardness focusing probe, an oscillator, an alloy shell, a spectrum analyzer and an analysis computer. The fiber optic probe uses sapphire as the optical window of the probe; the drilling fluid flow cell is placed on a transparent constant temperature platform (temperature range 20℃-150℃), and the influence of temperature parameters on the laser Raman scattering spectrum signal of hydrocarbons in the drilling fluid is preliminarily simulated. The device is used for the detection of hydrocarbons in drilling fluids by laser Raman spectroscopy on the ground, and can realize laboratory simulation of downhole drilling to detect hydrocarbons in drilling fluids. The document does not solve the problem that when the existing composite brine drilling fluid uses the distillation method to measure the insoluble solid content, the measurement process is complicated, the distillation and titration experiments are time-consuming, and the measurement error is large. Summary of the invention

[0007] The present invention provides an optical measuring device and method for measuring the solid phase content of a composite brine drilling fluid, aiming to overcome the problems in the prior art of measuring the insoluble solid phase content of the composite brine drilling fluid by distillation, such as complicated measurement process, long time consumption of distillation and titration experiments, and large measurement error.

[0008] To this end, the present invention provides an optical measurement device for the solid content of composite brine drilling fluid, including a laser light source module, a sample testing module, a transmitted light receiving module and a data processing and display module.

[0009] The laser light source module includes a multi-wavelength laser, and the multi-wavelength laser is used to emit a light beam;

[0010] The sample testing module comprises a sample testing stand and a cuvette, wherein the cuvette is placed in the sample testing stand, the sample to be tested is contained in the cuvette, and the light beam emitted from the multi-wavelength laser passes through the sample testing stand, the cuvette and the sample to be tested;

[0011] The transmitted light receiving module includes a photoelectric detector and a data acquisition display, the photoelectric detector is used to measure the light intensity of the sample to be tested, and the data acquisition display is used to collect the measurement data of the photoelectric detector and send the collected measurement data to the data processing and display module;

[0012] The data processing and display module includes a computer, and the computer is used for receiving and processing the measurement data.

[0013] Preferably, a connection limited position fixing frame is provided below the multi-wavelength laser, the sample test bench and the photoelectric detector.

[0014] Preferably, the color of the cuvette is white, and the light transmittance is four-sided.

[0015] Preferably, the cuvette is provided with scale lines.

[0016] Preferably, the multi-wavelength laser emits light waves with five wavelengths of 600nm to 1000nm, and the output power is 0.1 to 1000mW.

[0017] Preferably, the incident light power detected by the photodetector ranges from 0.001 μW to 1000 mW.

[0018] Preferably, the computer uses SCOM computing and processing software to process the measurement data.

[0019] A method for optically measuring the solid content of a composite brine drilling fluid comprises the following steps:

[0020] S1. Open the SCOM computing software, data acquisition display, multi-wavelength laser and photoelectric detector in the computer, and preheat the multi-wavelength laser and photoelectric detector until the working state is stable;

[0021] S2. Add the drilling fluid sample into the cuvette, put the cuvette containing the drilling fluid sample into the sample test bench, and emit a light beam from the multi-wavelength laser. The light beam passes through the sample test bench, the cuvette and the drilling fluid sample in the cuvette, and then enters the photoelectric detector. The photoelectric detector measures the transmitted light intensity of the drilling fluid sample in the sample test bench, and the data acquisition display collects and transmits the measured transmitted light intensity of the drilling fluid sample to the SCOM calculation processing software of the computer;

[0022] S3. When the test time reaches the preset time, the SCOM calculation processing software outputs the solid phase measurement results, takes out the cuvette containing the drilling fluid sample, repeats step S2 to complete the measurement of multiple drilling fluid samples, and after all drilling fluid samples are measured, turns off the multi-wavelength laser, photoelectric detector, data acquisition and display, and computer.

[0023] Preferably, preheating the multi-wavelength laser and the photodetector until the working state is stable in S1 is: when the error between the output light intensity of the multi-wavelength laser and the input light intensity of the photodetector is less than 0.01% and lasts for more than 2 minutes, it is determined that the working state of the multi-wavelength laser and the photodetector is stable.

[0024] Preferably, the preset duration in S3 is 15-30s.

[0025] Beneficial effects of the present invention:

[0026] 1. The optical measuring device and method for the solid phase content of composite brine drilling fluid provided by the present invention include a laser light source module, a sample testing module, a transmission light receiving module and a data processing and display module. The multi-wavelength laser emits a light beam, and the light beam passes through the sample testing bench, the cuvette and the drilling fluid sample in the cuvette, and then enters the photoelectric detector. The photoelectric detector measures the transmission light intensity of the drilling fluid sample in the sample testing bench, and the data acquisition display collects and transmits the transmission light intensity of the measured drilling fluid sample to the SCOM calculation processing software of the computer; by utilizing the transmittance difference and characteristics of different undissolved components in the drilling fluid under different light sources, the insoluble solid phase content in the composite brine drilling fluid is measured, and the measured solid phase result does not contain salt, eliminating the influence of inorganic salts or organic salts precipitated during the distillation process on the solid phase content measurement when the traditional distillation method is used to measure the solid phase content of the composite brine drilling fluid. Compared with the traditional distillation method, the present invention simplifies the measurement process, shortens the measurement time, has high measurement accuracy, improves its measurement efficiency, is simple to operate, and is safe and reliable.

[0027] 2. The optical measuring device and method for solid content of composite brine drilling fluid provided by the present invention have low manufacturing cost and are conducive to application and promotion.

[0028] 3. The optical measuring device and method for the solid content of composite brine drilling fluid provided by the present invention fix the relative positions of the multi-wavelength laser, the sample test bench and the photoelectric detector by setting a connecting limited position fixing frame under the multi-wavelength laser, the sample test bench and the photoelectric detector, so as to keep the beam path stable and not deviate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Figure 1 It is a schematic diagram of the structure of an optical measuring device for the solid content of composite brine drilling fluid.

[0031] Explanation of the accompanying drawings: 1. multi-wavelength laser; 2. light beam; 3. cuvette; 4. sample test bench; 5. photoelectric detector; 6. data acquisition display; 7. computer; 8. limit fixing frame. DETAILED DESCRIPTION

[0032] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0033] Embodiment 1:

[0034] like Figure 1 As shown, an optical measuring device for the solid content of composite brine drilling fluid includes a laser light source module, a sample testing module, a transmitted light receiving module and a data processing and display module.

[0035] The laser light source module comprises a multi-wavelength laser 1, and the multi-wavelength laser 1 is used to emit a light beam 2;

[0036] The sample testing module comprises a sample testing stand 4 and a cuvette 3, wherein the cuvette 3 is placed in the sample testing stand 4, the cuvette 3 contains a sample to be tested, and a light beam 2 emitted from a multi-wavelength laser 1 passes through the sample testing stand 4, the cuvette 3 and the sample to be tested;

[0037] The transmitted light receiving module includes a photodetector 5 and a data acquisition display 6. The photodetector 5 is used to measure the light intensity of the sample to be tested. The data acquisition display 6 is used to collect the measurement data of the photodetector 5 and send the collected measurement data to the data processing and display module.

[0038] The data processing and display module comprises a computer 7, and the computer 7 is used for receiving and processing the measurement data.

[0039] The present invention measures the insoluble solid content in the composite brine drilling fluid by utilizing the differences in optical characteristic parameters (including but not limited to transmittance, refractive index, extinction coefficient) of different undissolved components in the drilling fluid under different light sources and their changing patterns. The measured solid phase results do not contain salt, thereby eliminating the influence of inorganic salts or organic salts precipitated during the distillation process on the solid content measurement when the traditional distillation method is used to measure the solid content of the composite brine drilling fluid. Compared with the traditional distillation method, the present invention simplifies the measurement process, shortens the measurement time, has high measurement accuracy, improves its measurement efficiency, is simple to operate, and is safe and reliable. The provided optical measurement device for the solid content of the composite brine drilling fluid can conveniently and quickly monitor the solid content of the drilling fluid on site, and provides a basis for the refined regulation of the drilling fluid performance.

[0040] Preferably, a limited position fixing frame 8 is disposed below the multi-wavelength laser 1 , the sample test bench 4 and the photoelectric detector 5 .

[0041] By setting and connecting the limit fixing frame 8 under the multi-wavelength laser 1, the sample test bench 4 and the photodetector 5, the relative positions of the three are fixed, so that the path of the light beam 2 remains stable and does not deviate. In actual use, the above technical solution is used to fix the main measuring components, so that the light beam propagation path can be kept stable during the measurement process, and the measurement error caused by the change of the light beam propagation path can be avoided, thereby improving the accuracy of the measurement. The structure of the specific limit fixing frame 8 is the same or different, and it can meet the actual needs.

[0042] Preferably, the color of the cuvette 3 is white, and the light transmittance is four-sided.

[0043] Improve the penetration of the light beam; Specifically, the cuvette 3 is a quartz cuvette; its function is to contain the drilling fluid sample to be tested. In actual use, the light transmittance of the cuvette 3 is four-sided, and any side can be selected to align the light beam for measurement, which simplifies the measurement operation process.

[0044] Preferably, the cuvette 3 is provided with scale lines.

[0045] The scale lines include the minimum sample amount scale line. The minimum sample amount scale line required for measurement is set to ensure that the light beam 2 can pass through and measure the drilling fluid sample. Its length is 0.5-2.0 cm, width is 0.5-2.0 cm, and height is 4 cm. There are multiple size specifications, which can be selected according to actual needs.

[0046] The above-mentioned cuvettes of different sizes can be flexibly selected according to the amount of drilling fluid sample to be measured, so that the drilling fluid level in the cuvette 3 is above the minimum sample amount scale line. The minimum sample amount scale line on the quartz cuvette 3 can quickly determine whether the added sample amount meets the measurement requirements, clearly and clearly.

[0047] Preferably, a test groove is provided in the middle of the upper portion of the sample test stand 4 to facilitate placement of the cuvette 3 .

[0048] Preferably, the multi-wavelength laser 1 emits light waves with five wavelengths of 600nm to 1000nm, and the output power is 0.1 to 1000mW.

[0049] In actual use, the wavelength of the light wave emitted by the multi-wavelength laser 1 can be switched during the measurement process to perform multi-wavelength transmission measurement on the drilling fluid sample to be measured, thereby making the measurement result more comprehensive and accurate.

[0050] Preferably, the incident light power detected by the photodetector 5 ranges from 0.001 μW to 1000 mW.

[0051] The output and receiving powers of the multi-wavelength laser 1 and the photodetector 5 adopt the above technical solution, which not only meets the measurement requirements of commonly used composite brine drilling fluids, but also saves costs.

[0052] Preferably, the computer 7 uses SCOM computing and processing software to process the measurement data.

[0053] The SCOM calculation and processing software is an existing software, which is convenient for processing measurement data as needed.

[0054] Embodiment 2:

[0055] Based on Example 1, a method for optically measuring the solid content of a composite brine drilling fluid comprises the following steps:

[0056] S1, open the SCOM computing software, data acquisition display 6, multi-wavelength laser 1 and photodetector 5 in the computer 7, and preheat the multi-wavelength laser 1 and photodetector 5 until the working state is stable;

[0057] S2, add the drilling fluid sample into the cuvette 3, put the cuvette 3 containing the drilling fluid sample into the sample test bench 4, the multi-wavelength laser 1 emits a light beam, the light beam passes through the sample test bench 4, the cuvette 3 and the drilling fluid sample in the cuvette 3, and then enters the photodetector 5, the photodetector 5 measures the transmitted light intensity of the drilling fluid sample in the sample test bench 4, and the data acquisition display 6 collects and transmits the measured transmitted light intensity of the drilling fluid sample to the SCOM calculation processing software of the computer 7;

[0058] In actual operation, specifically, a certain amount of drilling fluid sample is measured with a pipette and slowly added to the quartz cuvette 3, and bubbles are avoided during the sample addition process. The drilling fluid level reaches the scale line of the quartz cuvette 3, and then the quartz cuvette 3 containing the drilling fluid sample is placed in the test groove of the sample test bench 4, so that the quartz cuvette 3 is centered in the test groove. The test groove and the left and right sides of the sample test bench are both hollow structures. The light beam 2 can be directly irradiated into the quartz cuvette 3 after being emitted from the multi-wavelength laser 1. During the propagation of the light beam, there is no other obstruction except passing through the quartz cuvette 3 and the drilling fluid sample. Then the photoelectric detector 5 measures the transmitted light intensity of the drilling fluid sample to be tested, and the transmitted light intensity of the measured sample is collected and transmitted to the SCOM calculation processing software of the computer 7 through the data acquisition display 6;

[0059] S3, when the test time reaches the preset time, the SCOM calculation processing software outputs the solid phase measurement result, takes out the cuvette 3 containing the drilling fluid sample, repeats step S2 to complete the measurement of multiple drilling fluid samples, and after all drilling fluid samples are measured, turns off the multi-wavelength laser 1, the photoelectric detector 5, the data acquisition and display 6 and the computer 7;

[0060] Preferably, preheating the multi-wavelength laser 1 and the photodetector 5 until the working state is stable in S1 is: when the error between the output light intensity of the multi-wavelength laser 1 and the input light intensity of the photodetector 5 is less than 0.01% and lasts for more than 2 minutes, it is determined that the working state of the multi-wavelength laser 1 and the photodetector 5 is stable.

[0061] In actual use, preheating the multi-wavelength laser 1 and the photodetector 5 according to the above technical solution can make the light beams emitted and received during the measurement process more stable.

[0062] Preferably, the preset duration in S3 is 15-30s.

[0063] The measurement is performed according to the preset time of the above technical solution, so that the entire process of receiving, recording, transmitting, processing and outputting the measurement results of the optical signal during the sample measurement is completed, which shortens the measurement time and improves the measurement efficiency.

[0064] Embodiment 3:

[0065] First, the following 6 kinds of composite brine drilling fluids with known solid content were prepared, and the solid content was measured by using the composite brine drilling fluid solid content optical measurement device and the composite brine drilling fluid solid content optical measurement method to verify the accuracy and reliability of the composite brine drilling fluid solid content optical measurement device and the measurement method, and compared with the measurement results of the distillation method, and the results are shown in Table 1. In addition, the single sample measurement time of the present invention and the distillation method was measured. The single measurement time of the present invention is less than 3 minutes, while the single measurement time of the distillation method is 2 to 3 hours.

[0066] 1# drilling fluid: 4% bentonite + 0.02% NaOH + 0.2% PAC-LV (polyanionic cellulose) + 2% white asphalt + 5% ultrafine calcium carbonate + 10% barite + 5% NaCl + 5% KCl

[0067] 2# drilling fluid: 4% bentonite + 0.02% NaOH + 0.2% PAC-LV (polyanionic cellulose) + 2% white asphalt + 4% ultrafine calcium carbonate + 8% barite + 5% NaCl + 10% KCl

[0068] 3# drilling fluid: 4% bentonite + 0.02% NaOH + 0.2% PAC-LV (polyanionic cellulose) + 2% white asphalt + 3% ultrafine calcium carbonate + 6% barite + 10% NaCl + 10% KCl

[0069] 4# drilling fluid: 4% bentonite + 0.02% NaOH + 0.2% PAC-LV (polyanionic cellulose) + 2% white asphalt + 3% ultrafine calcium carbonate + 3% barite + 10% NaCl + 20% KCl

[0070] 5# drilling fluid: 4% bentonite + 0.02% NaOH + 0.2% PAC-LV (polyanionic cellulose) + 2% white asphalt + 3% ultrafine calcium carbonate + 5% barite + 5% NaCl + 5% KCl + 5% potassium formate + 5% sodium formate

[0071] 6# drilling fluid: 4% bentonite + 0.02% NaOH + 0.2% PAC-LV (polyanionic cellulose) + 2% white asphalt + 3% ultrafine calcium carbonate + 5% barite + 5% NaCl + 5% KCl + 10% potassium formate + 10% sodium formate

[0072] Table 1 Comparison of solid phase measurement results of composite brine drilling fluid

[0073]

[0074] Note: Relative error of optical method = (actual solid content - optical method measurement result) / actual solid content × 100%;

[0075] Relative error of distillation method = (measurement result of distillation method - actual solid content) / actual solid content × 100%.

[0076] The results in Table 1 show that the results obtained by the optical measurement method for composite brine drilling fluid are very close to the actual solid content of the drilling fluid, with a relative error of less than 4.29%, and are almost independent of the salt content and type of salt in the drilling fluid; while the deviation between the results measured by the distillation method and the actual solid content is large, with a relative error of 39.5% to 234.2%, and the higher the salt content in the drilling fluid, the greater the error in the solid content measurement. It can be seen that the solid content of the composite brine drilling fluid measured by the present invention is closer to its actual solid content, and is not affected by the type and amount of salt in the drilling fluid, and the measurement result is highly accurate and reliable.

[0077] Moreover, during the measurement process using the distillation method, the increase in temperature will cause the high molecular organic matter and other materials in the drilling fluid to oxidize and decompose, producing smoke accompanied by a pungent odor, which is not conducive to the health of operators. However, the optical measurement method used in the present invention will not change the state of the drilling fluid sample to be measured, and no unpleasant odor will be generated, which is safe and environmentally friendly.

[0078] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. An optical measuring device for solid content of composite brine drilling fluid, Features: It includes laser light source module, sample testing module, transmitted light receiving module and data processing and display module. The laser light source module comprises a multi-wavelength laser (1), and the multi-wavelength laser (1) is used to emit a light beam (2); The sample testing module comprises a sample testing stand (4) and a cuvette (3), wherein the cuvette (3) is placed in the sample testing stand (4), the cuvette (3) contains a sample to be tested, and a light beam (2) emitted from a multi-wavelength laser (1) passes through the sample testing stand (4), the cuvette (3) and the sample to be tested; The transmitted light receiving module comprises a photodetector (5) and a data acquisition display (6), wherein the photodetector (5) is used to measure the light intensity of the sample to be tested, and the data acquisition display (6) is used to collect measurement data of the photodetector (5) and send the collected measurement data to the data processing and display module; The data processing and display module comprises a computer (7), and the computer (7) is used for receiving and processing measurement data.

2. The optical measuring device for solid content of composite brine drilling fluid according to claim 1, Features: A limited position fixing frame (8) is provided below the multi-wavelength laser (1), the sample test bench (4) and the photoelectric detector (5).

3. The optical measuring device for solid content of composite brine drilling fluid according to claim 1, Features: The color of the cuvette (3) is white, and the light transmittance is such that light can pass through from all sides.

4. The optical measuring device for solid content of composite brine drilling fluid according to claim 3, Features: The cuvette (3) is provided with scale lines.

5. The optical measuring device for solid content of composite brine drilling fluid according to claim 1, Features: The multi-wavelength laser (1) emits light waves with five wavelengths of 600nm to 1000nm, and the output power is 0.1 to 1000mW.

6. The optical measuring device for solid content of composite brine drilling fluid according to claim 1, Features: The incident light power detected by the photoelectric detector (5) ranges from 0.001 μW to 1000 mW.

7. The optical measuring device for solid content of composite brine drilling fluid according to claim 1, Features: The computer (7) uses SCOM calculation processing software to process the measurement data.

8. An optical measurement method for solid content of composite brine drilling fluid, Features: The steps include: S1, opening the SCOM computing software, the data acquisition display (6), the multi-wavelength laser (1) and the photoelectric detector (5) in the computer (7), and preheating the multi-wavelength laser (1) and the photoelectric detector (5) until the working state is stable; S2, adding a drilling fluid sample into a cuvette (3), placing the cuvette (3) containing the drilling fluid sample into a sample test stand (4), using a photoelectric detector (5) to measure the transmitted light intensity of the drilling fluid sample in the sample test stand (4), and a data acquisition display (6) to collect and transmit the measured transmitted light intensity of the drilling fluid sample to the SCOM calculation processing software of a computer (7); S3. When the test time reaches a preset time, the SCOM calculation processing software outputs the solid phase measurement result, takes out the cuvette (3) containing the drilling fluid sample, repeats step S2 to complete the measurement of multiple drilling fluid samples, and after all drilling fluid samples are measured, turns off the multi-wavelength laser (1), the photoelectric detector (5), the data acquisition and display (6) and the computer (7).

9. The optical measurement method for solid content of composite brine drilling fluid according to claim 8, Features: In S1, the multi-wavelength laser (1) and the photodetector (5) are preheated until the working state is stable: when the error between the output light intensity of the multi-wavelength laser (1) and the input light intensity of the photodetector (5) is less than 0.01% and lasts for more than 2 minutes, it is determined that the working state of the multi-wavelength laser (1) and the photodetector (5) is stable.

10. The optical measurement method for solid content of composite brine drilling fluid according to claim 3, Features: The preset duration in S3 is 15-30s.

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