阅读说明：本技术 一种富油煤原位热解反应程度监测评价方法 (Method for monitoring and evaluating degree of in-situ pyrolysis reaction of oil-rich coal ) 是由 付德亮 杨甫 田涛 王振东 段中会 马丽 李娟� 于 2021-08-30 设计创作，主要内容包括：本发明提供一种富油煤原位热解反应程度监测评价方法,包括如下步骤：建立热解反应阶段标准指标；对富油煤的原位热解开采,开采过程中,在抽采井内对进行分期产物收集,采样要求对井口所得全组分产物进行收集；获得井口产物以后进行产物的组分特征分析,获得井下热解反应阶段指标；通过热解反应阶段标准指标与井下热解产物指标的对比,判断井下热解程度。本发明基于室内富油煤热模拟实验所得热解产物演化特征,对照原位热解产物与室内热模拟实验建立的反应程度指标,进而分析和判定原位热解反应程度及转化率,为调整热解提取油气资源方法提供关键参考。(The invention provides a method for monitoring and evaluating the in-situ pyrolysis reaction degree of rich coal, which comprises the following steps: establishing standard indexes of a pyrolysis reaction stage; in-situ pyrolysis mining of the oil-rich coal, collecting staged products in a mining well in the mining process, and collecting all-component products obtained at a well mouth according to sampling requirements; performing component characteristic analysis on the product after obtaining the wellhead product to obtain indexes of the underground pyrolysis reaction stage; and judging the underground pyrolysis degree by comparing the standard index of the pyrolysis reaction stage with the index of the underground pyrolysis product. According to the method, based on the evolution characteristics of the pyrolysis product obtained in the indoor oil-rich coal thermal simulation experiment, the reaction degree index established by the in-situ pyrolysis product and the indoor thermal simulation experiment is contrasted, so that the in-situ pyrolysis reaction degree and the conversion rate are analyzed and judged, and a key reference is provided for adjusting the method for extracting the oil gas resource by pyrolysis.)

1. A method for monitoring and evaluating the in-situ pyrolysis reaction degree of oil-rich coal is characterized by comprising the following steps: the method comprises the following steps:

step A, establishing a standard, and sampling a coal bed in an in-situ pyrolysis area to obtain a representative pyrolysis sample; carrying out a simulation experiment under the same underground pyrolysis condition by using an indoor experimental device, accurately obtaining pyrolysis products of each reaction stage in the experimental process, carrying out component characteristic analysis on the products, and respectively establishing standard indexes of the pyrolysis reaction stages;

b, carrying out in-situ pyrolysis mining on the oil-rich coal, wherein in the mining process, stage product collection is carried out in an extraction well, and sampling requirements are carried out on all-component products obtained at a well mouth;

c, analyzing the component characteristics of the product after obtaining the wellhead product to obtain indexes of the underground pyrolysis reaction stage;

and D, judging the underground pyrolysis degree through comparing the standard index of the pyrolysis reaction stage with the index of the underground pyrolysis product. And respectively judging the underground pyrolysis degree through the comparison of indexes of the pyrolysis reaction stage obtained by the experiment and indexes of underground pyrolysis products, and determining the conversion rate of the in-situ pyrolysis reaction of the oil-rich coal in a specific interval of the obtained in-situ pyrolysis reaction degree.

2. The method for monitoring and evaluating the reaction degree of in-situ pyrolysis of oil-rich coal according to claim 1, characterized by comprising the following steps: the component characteristics comprise gaseous components and yield generated by pyrolysis, methane carbon isotope, liquid hydrocarbon components and yield.

3. The in-situ pyrolysis reaction of oil-rich coal according to claim 1 or 2The degree monitoring and evaluating method is characterized in that: the indexes of the underground pyrolysis reaction stage and the standard indexes of the pyrolysis reaction stage comprise product gas-oil ratio and CO₂Gas proportion, gas drying coefficient and indexes of methane-carbon isotope pyrolysis reaction stage.

4. The method for monitoring and evaluating the in-situ pyrolysis reaction degree of the oil-rich coal according to claim 3, characterized by comprising the following steps: the staged product is collected as: in the stage of increasing the yield of the product in the initial stage of pyrolysis, the sampling interval is once every week, and the sampling interval is gradually adjusted to once every three days along with the progress of pyrolysis mining operation until once every day in the later stage.

Technical Field

The invention belongs to the technical field of underground in-situ development of energy resources, and particularly relates to an in-situ pyrolysis reaction degree monitoring and evaluating method for oil-rich coal, which is used in the field of unconventional energy in-situ mining of oil-rich coal, oil shale, heavy oil and the like.

Background

In recent years, the underground in-situ pyrolysis technology of oil shale and coal is more and more emphasized by people, the method manufactures an artificial fracture network in a rock stratum through the existing drilling technology and fracturing method, then high-temperature heat carriers such as superheated steam or superheated hydrocarbon gas are injected into the artificial fracture network, the underground rock stratum is heated, organic matters are promoted to be pyrolyzed to form oil gas, and finally the formed oil gas resources are extracted to the ground and utilized. The main patents disclosed at present are 'a coal bed convection heating system (202010989880.5) for in-situ pyrolysis of rich coal', 'a process for in-situ pyrolysis mining and utilizing deep coal' (202110074115.5) 'a system and a method for underground in-situ pyrolysis of coal (202010991619.9)'.

The method has the advantages of reducing ground dry distillation engineering, avoiding the need of constructing an underground mining roadway, having a large coal mining depth range, reducing carbon emission, avoiding surface subsidence and the like, but is limited in that the pyrolysis process is carried out underground, the pyrolysis degree of underground rich oil coal resources cannot be directly judged, and certain limitations are brought to the efficient operation of in-situ pyrolysis engineering. Firstly, if the heat injection and extraction operation is stopped before complete pyrolysis, the waste of underground resources is caused; secondly, when the pyrolysis product output is less due to incomplete pyrolysis caused by heat loss or other reasons, if the pyrolysis reaction degree cannot be judged correctly, the operation may be stopped because the pyrolysis of the oil-rich coal is close to termination; in addition, when the pyrolysis reaction approaches the final stage, if the judgment cannot be made correctly, the pyrolysis products caused by other reasons may be reduced by mistake, and unnecessary resource waste is caused when the reasons are searched.

At present, the general idea about judging the degree of in-situ pyrolysis reaction comprises methods such as in-situ coal seam sampling and in-situ coal seam monitoring, but a specific scheme is not formed due to the fact that the corresponding cost is too high and the implementation performance is not strong. The indoor thermal simulation experiment is mature in development at the present stage and low in cost, and meanwhile, the difference between pyrolysis products in different stages in the underground pyrolysis process and the indoor pyrolysis process is small, so that the comparison analysis of the underground pyrolysis process and the indoor pyrolysis process has good pyrolysis degree judgment and evaluation application value.

Disclosure of Invention

Aiming at the explanation of the background technology, the invention provides a method for monitoring and evaluating the in-situ pyrolysis reaction degree of oil-rich coal.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for monitoring and evaluating the in-situ pyrolysis reaction degree of oil-rich coal comprises the following steps:

step A, establishing a standard, and sampling a coal bed in an in-situ pyrolysis area to obtain a representative pyrolysis sample; carrying out a simulation experiment under the same underground pyrolysis condition by using an indoor experimental device, accurately obtaining pyrolysis products of each reaction stage in the experimental process, carrying out component characteristic analysis on the products, and respectively establishing standard indexes of the pyrolysis reaction stages;

b, carrying out in-situ pyrolysis mining on the oil-rich coal, wherein in the mining process, stage product collection is carried out in an extraction well, and sampling requirements are carried out on all-component products obtained at a well mouth;

c, analyzing the component characteristics of the product after obtaining the wellhead product to obtain indexes of the underground pyrolysis reaction stage;

and D, judging the underground pyrolysis degree through comparing the standard index of the pyrolysis reaction stage with the index of the underground pyrolysis product. And respectively judging the underground pyrolysis degree through the comparison of indexes of the pyrolysis reaction stage obtained by the experiment and indexes of underground pyrolysis products, and determining the conversion rate of the in-situ pyrolysis reaction of the oil-rich coal in a specific interval of the obtained in-situ pyrolysis reaction degree.

In the above technical scheme, the component characteristics include gaseous components and yield, methane carbon isotope, liquid hydrocarbon components and yield generated by pyrolysis.

In the above technical scheme, the indexes of the underground pyrolysis reaction stage and the standard indexes of the pyrolysis reaction stage comprise product gas-oil ratio and CO₂Gas proportion, gas drying coefficient and indexes of methane-carbon isotope pyrolysis reaction stage.

In the above technical scheme, the collection of the stage products is as follows: in the stage of increasing the yield of the product in the initial stage of pyrolysis, the sampling interval is once every week, and the sampling interval is gradually adjusted to once every three days along with the progress of pyrolysis mining operation until once every day in the later stage.

The method is based on the evolution characteristics of pyrolysis products obtained by an indoor oil-rich coal thermal simulation experiment, and specifically comprises a product gas-oil ratio, gas components, a drying coefficient, a methane isotope and the like, on the basis, an oil-rich coal pyrolysis reaction degree evaluation index is established, products of an oil-rich coal in-situ pyrolysis extraction well are sampled in stages, characteristic analysis such as the pyrolysis product gas-oil ratio, the gas components, the drying coefficient and the methane isotope is carried out, on the basis, the in-situ pyrolysis reaction degree and the conversion rate are analyzed and judged by contrasting the in-situ pyrolysis products and the reaction degree index established by the indoor thermal simulation experiment, and a key reference is provided for adjusting the underground in-situ pyrolysis oil gas resource extraction method.

Drawings

In order to more clearly illustrate the embodiments of the patent of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the patent of the present invention, and other drawings can be obtained by those skilled in the art without inventive exercise.

FIG. 1 shows the results of the calculation of each index and the fitting of a polynomial in example 1.

FIG. 2 shows the results of the calculation of each index and the fitting result of the polynomial in example 2.

FIG. 3 is a schematic flow chart of the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given in the present patent application without inventive step, shall fall within the scope of protection of the present patent application.

Referring to fig. 1, an in-situ pyrolysis reaction degree monitoring and evaluating method for oil-rich coal as an embodiment includes the steps of:

step A, establishing a standard, and sampling a coal bed in an in-situ pyrolysis area to obtain a representative pyrolysis sample; carrying out a simulation experiment under the same underground pyrolysis condition by using an indoor experimental device, accurately obtaining pyrolysis products of each reaction stage in the experimental process, and carrying out component characteristic analysis on the products, wherein the component characteristics comprise gaseous components and yield, methane carbon isotopes, and liquid hydrocarbon components and yield generated by pyrolysis; respectively establishing standard indexes of a pyrolysis reaction stage, wherein the standard indexes of the pyrolysis reaction stage comprise product gas-oil ratio, CO2 gas ratio, gas drying coefficient and indexes of a methane carbon isotope pyrolysis reaction stage;

and B, carrying out in-situ pyrolysis mining on the oil-rich coal, wherein in the mining process, stage product collection is carried out in an extraction well, sampling requirements are carried out on all-component products obtained at a well mouth, and the stage product collection is as follows: in the stage of the initial stage of pyrolysis, the yield of the product is gradually increased, the sampling interval is once every week, and the sampling interval is gradually adjusted to once every three days along with the progress of pyrolysis mining operation until the sampling interval is once every day finally;

c, analyzing the component characteristics of the product after obtaining the wellhead product to obtain indexes of the underground pyrolysis reaction stage, wherein the indexes of the underground pyrolysis reaction stage and the standard indexes of the pyrolysis reaction stage comprise product gas-oil ratio, CO2 gas proportion, gas drying coefficient and indexes of the methane carbon isotope pyrolysis reaction stage;

and D, judging the underground pyrolysis degree through comparing the standard index of the pyrolysis reaction stage with the index of the underground pyrolysis product. And respectively judging the underground pyrolysis degree through the comparison of indexes of the pyrolysis reaction stage obtained by the experiment and indexes of underground pyrolysis products, and determining the conversion rate of the in-situ pyrolysis reaction of the oil-rich coal in a specific interval of the obtained in-situ pyrolysis reaction degree.

First, taking the injection of high-temperature N2 at 550 ℃ for in-situ pyrolysis mining of rich coal as an example, the detailed description of the process is carried out:

and secondly, obtaining an oil-rich coal sample of the target coal bed through drilling construction.

Weighing 100g of an oil-rich coal sample, utilizing a pyrolysis experimental device in a laboratory, wherein the experimental device adopts an experimental device ZL2020200960488 for coal pyrolysis, carrying out an indoor pyrolysis experiment of the oil-rich coal, the experimental temperature is 550 ℃, the reaction atmosphere is N2, the gas flow rate is 20ml/min, along with the progress of pyrolysis reaction, respectively collecting one part of pyrolysis gaseous hydrocarbon and one part of liquid hydrocarbon every 20 minutes at a product collecting end, and the reaction time is 240 minutes, so that 12 parts of gaseous hydrocarbon and liquid hydrocarbon products are obtained.

Thirdly, the gas hydrocarbon and the liquid hydrocarbon products obtained by pyrolysis are respectively subjected to qualitative and quantitative component determination by using a chromatographic internal standard method, and a mass spectrometer is used for performing methane carbon isotope determination.

Fourthly, standard indexes of the pyrolysis reaction stage are established after the data are obtained, and the calculation results of the indexes in the embodiment 1 of the table 1 are shown as follows:

the calculation method of the gas-oil ratio comprises the following steps: GOR is Mg/Mo. Wherein GOR is the gas-oil ratio and is dimensionless; mg is the mass of hydrocarbon gas, kg; mo is the mass of liquid hydrocarbon, kg.

The ii CO2 gas proportion calculation method comprises the following steps: CDMI (Nc/(Nc + Nm) × 100%. Wherein CDMI is CO2 gas proportion and is dimensionless; nc is the concentration of CO2 in the gas component, mol/L; nm is the methane concentration in the gas component, mol/L.

And iii, calculating a gas drying coefficient by the following method: Dc-C1/C1-5-100%. Wherein Dc is the gas drying coefficient, and C1 is the methane concentration in the gas component, mol/L; c1-5 is total gaseous hydrocarbon concentration, mol/L.

And iv, actually measuring the methane carbon isotope index by an isotope mass spectrometer.

Table 1 calculation results of each index of example 1

And fifthly, injecting 550 ℃ high-temperature N2 into the underground rich oil coal bed while establishing the indexes, carrying out underground in-situ pyrolysis exploitation to extract coal-based oil and gas resources, collecting products in an extraction well in the exploitation process, gradually adjusting the sampling interval to once every three days at the stage of gradually increasing the product yield in the initial stage of pyrolysis until once every day in the later stage along with the implementation of pyrolysis exploitation operation once every week, and collecting all-component products obtained from a wellhead according to sampling requirements.

Sixthly, analyzing the component characteristics of the products after obtaining the wellhead products, wherein the components specifically comprise gaseous components and yield generated by pyrolysis, methane carbon isotopes, liquid hydrocarbon components and yield.

Obtaining index parameters of gas-oil ratio, CO2 gas ratio, gas drying coefficient and methane carbon isotope based on pyrolysis products, wherein the parameters are gas-oil ratio GOR (21), CO2 gas ratio CDMI (35), gas drying coefficient Dc (89) and methane carbon isotope delta 13C (36.8) per mill on 80 days.

Comparing the pyrolysis reaction stage index and the downhole pyrolysis product index obtained through experiments, and respectively judging the downhole pyrolysis degree, wherein the conversion rate is about 69% based on the gas-oil ratio GOR of 21, the conversion rate is about 67% based on the CO2 gas ratio CDMI of 35, the conversion rate is about 71% based on the gas drying coefficient Dc of 89, and the conversion rate is about 69% based on the methane carbon isotope δ 13C of-36.8%.

GOR conversion equation：y＝2E-07x⁵-4E-05x⁴+0.002x³-0.039x²+ 0.3578x-0.3495 R²＝0.9998

Conversion equation for CDMI: y 2E-06x⁴-0.0006x³+0.0566x²-2.8062x +98.539 R²＝0.9998

Dc conversion equation: y 6E-09x⁶-2E-06x⁵+0.0002x⁴-0.0135x³+ 0.3911x²-4.6338x+67.235 R²＝0.9562

Formula for conversion of carbon methane isotope δ 13C: y 1E-09x⁶-4E-07x⁵+ 5E-05x⁴-0.0031x³+0.0874x²-0.9499x-39.402 R²＝0.9653

Wherein: y is corresponding GOR, CDMI, Dc, methane carbon isotope delta 13C numerical value, x is each index calculation result numerical value in the embodiment, and finally a curve can be generated for visual representation.

The ninthly conversion rate judgment result is based on the four different parameter indexes, different reaction degree results can be obtained, and the specific interval of the in-situ pyrolysis reaction degree can be obtained based on the result, so that the conversion rate of the in-situ pyrolysis reaction of the rich oil coal can be determined to be about 67-71% based on the four-parameter comprehensive judgment.

The prior art of this conversion can refer to geological science and technology intelligence 2018, 37 (1): 108-114, which is disclosed in the Bohai middle area under different pyrolysis experimental conditions.

In the second embodiment, the following is a detailed description of the process of the method by taking the injection of superheated steam with a high temperature of 550 ℃ for in-situ pyrolysis and mining of rich coal as an example:

and secondly, obtaining an oil-rich coal sample of the target coal bed through drilling construction.

Weighing 100g of an oil-rich coal sample, carrying out an indoor pyrolysis experiment of the oil-rich coal by using a pyrolysis experimental device in a laboratory, wherein the experiment temperature is 550 ℃, the reaction atmosphere is water vapor, the steam flow rate is 20ml/min, along with the progress of the pyrolysis reaction, respectively collecting one part of pyrolysis gaseous hydrocarbon and one part of pyrolysis liquid hydrocarbon at a product collecting end every 20 minutes, and the reaction time is 240 minutes, so that 12 parts of gaseous hydrocarbon and liquid hydrocarbon products are obtained.

Thirdly, the gas hydrocarbon and the liquid hydrocarbon products obtained by pyrolysis are respectively subjected to qualitative and quantitative component determination by using a chromatographic internal standard method, and a mass spectrometer is used for performing methane carbon isotope determination.

And fourthly, starting to establish index parameters of the pyrolysis reaction degree after data are obtained, and referring to the calculation results of each index in the embodiment 2 of the table 2, wherein:

the calculation method of the gas-oil ratio comprises the following steps: GOR is Mg/Mo. Wherein GOR is the gas-oil ratio and is dimensionless; mg is the mass of hydrocarbon gas, kg; mo is the mass of liquid hydrocarbon, kg.

The ii CO2 gas proportion calculation method comprises the following steps: CDMI (Nc/(Nc + Nm) × 100%. Wherein CDMI is CO2 gas proportion and is dimensionless; nc is the concentration of CO2 in the gas component, mol/L; nm is the methane concentration in the gas component, mol/L. And (3) calculating the result:

and iii, calculating a gas drying coefficient by the following method: Dc-C1/C1-5-100%. Wherein Dc is the gas drying coefficient, and C1 is the methane concentration in the gas component, mol/L; c1-5 is total gaseous hydrocarbon concentration, mol/L.

And iv, actually measuring the methane carbon isotope index by an isotope mass spectrometer.

Table 2 calculation results of each index of example 2

And fifthly, injecting 550 ℃ high-temperature N2 into the underground rich oil coal bed while establishing the indexes, carrying out underground in-situ pyrolysis exploitation to extract coal-based oil and gas resources, collecting products in an extraction well in the exploitation process, gradually adjusting the sampling interval to once every three days at the stage of gradually increasing the product yield in the initial stage of pyrolysis until once every day in the later stage along with the implementation of pyrolysis exploitation operation once every week, and collecting all-component products obtained from a wellhead according to sampling requirements.

Sixthly, analyzing the component characteristics of the products after obtaining the wellhead products, wherein the components specifically comprise gaseous components and yield generated by pyrolysis, methane carbon isotopes, liquid hydrocarbon components and yield.

Obtaining index parameters of gas-oil ratio, CO2 gas ratio, gas drying coefficient and methane carbon isotope based on pyrolysis products, wherein the parameters are gas-oil ratio GOR (good oil ratio) 148, CO2 gas ratio CDMI (60), gas drying coefficient Dc (94) and methane carbon isotope delta 13C (36.7) thousandth at the 95 th day.

Comparing the pyrolysis reaction stage index and the downhole pyrolysis product index obtained through experiments, and respectively judging the downhole pyrolysis degree, wherein the conversion rate is about 79% based on the gas-oil ratio GOR ═ 148, about 75% based on the CO2 gas ratio CDMI ═ 60, about 73% based on the gas drying coefficient Dc ═ 94, and about 78% based on the methane carbon isotope δ 13C ═ 36.7 ‰.

GOR conversion equation: y-5E-09 x6+2E-06x5-0.0002x4+ 0.0062x3-0.099x2+0.681 x-0.4978R²＝0.9998

Conversion equation for CDMI: y-1E-09 x⁶+3E-07x⁵-4E-05x⁴+ 0.0022x³-0.0634x²+0.8959x+51.921 R²＝0.9877

Dc conversion equation: y-8E-09 x⁶-2E-06x⁵+0.0003x⁴-0.0153x³+ 0.4222x²-4.5931x+65.491 R²＝0.9457

Formula for conversion of carbon methane isotope δ 13C: y 2E-09x⁶-6E-07x⁵+ 7E-05x⁴-0.0037x³+0.0941x²-0.9156x-40.54 R²＝0.958

Wherein: y is corresponding GOR, CDMI, Dc, methane carbon isotope delta 13C numerical value, x is each index calculation result numerical value in the embodiment, and finally a curve can be generated for visual representation.

Ninthly, based on the four-parameter comprehensive judgment, the conversion rate of the in-situ pyrolysis reaction of the rich-oil coal can be determined to be about 73-79%.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and shall be covered by the protection scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the protection scope of the claims.