Method for testing oil and gas content parameters of shale

Abstract

The invention relates to the technical field of shale oil and gas reservoir exploration, in particular to a shale oil and gas content parameter testing method which comprises the following steps: taking a rock core just taken out of a cylinder as an original sample, performing sample desorption on the original sample, recording the total desorption gas amount Gad, and obtaining a desorption sample; preparing a frozen sample and a normal-temperature sample based on the desorption sample, applying the frozen sample and the normal-temperature sample to a pyrolysis test, and obtaining a corresponding hydrocarbon content parameter group S at a set temperature based on the pyrolysis test; and combining the total desorption gas quantity Gad and the hydrocarbon content parameter group S into a corresponding oil-gas content calculation formula to obtain related parameters of the oil-gas content. According to the technical scheme, the steps of sample desorption, sample preservation and sample pyrolysis are formulated according to the characteristics of substances contained in the core, the oil and gas content in the medium-high maturity shale oil and gas reservoir sample can be tested at the same time, and compared with the prior art, the technical scheme considers more comprehensive problems and can ensure that the test result is accurate and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of shale oil and gas reservoir exploration, and in particular to a method for testing shale oil and gas content parameters. Background Art

[0002] At present, unconventional oil and gas resources have been developed on a large scale, among which shale oil and gas are expected to become the main force for increasing crude oil and natural gas reserves and production. In the exploration and evaluation of shale oil and gas reservoirs, oil content is the basic parameter for predicting its resource potential and an important reference for in-depth research on the enrichment mechanism of shale oil and gas.

[0003] For medium-to-high maturity shale reservoirs, which have just entered the gas generation stage after the oil generation window, the reservoir contains a certain amount of gaseous hydrocarbons and crude oil at the same time. When evaluating the resource potential of the reservoir, both should be quantitatively evaluated. At the same time, the quantitative characterization of the gas-oil ratio has a certain reference significance in evaluating and predicting the mobility of crude oil in shale oil reservoirs. At present, according to the "Method for Determination of Gas Content in Shale Gas" (SY / T6940-2020), the gas content of high-to-overmature marine shale reservoirs is tested, but the oil content of the reservoir cannot be tested. The oil content evaluation methods include chloroform asphalt "A", rock pyrolysis method and nuclear magnetic resonance testing method. The above methods do not perform special treatment on the rock samples when characterizing the hydrocarbon content in the reservoir. Since the light hydrocarbon component content in the medium-to-high maturity shale reservoir is high and volatile, it is impossible to accurately measure the gaseous hydrocarbon content in the sample and the light component content in the crude oil.

[0004] In order to accurately measure the amount of crude oil in the reservoir, the low-temperature freezing method is currently used to preserve and crush samples to avoid hydrocarbon loss during the surface circulation of core samples. Then a small amount of powder samples are taken to perform programmed heating of rock pyrolysis according to "Rock Pyrolysis Analysis" (GB / T18602-2012) to measure the hydrocarbon content. Although this method avoids the loss of some light liquid hydrocarbons to a certain extent, it cannot distinguish the residual gaseous hydrocarbon content in the test sample and calculate the gas loss of the sample, and it cannot estimate the recoverable crude oil content in the sample. Therefore, it is urgent to establish a method that can quickly, continuously and accurately test the gas content and recoverable oil content in the sample. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, the present invention proposes a method for testing shale oil and gas content parameters, which can quickly, continuously and accurately quantitatively characterize the gas content and recoverable oil content in medium-to-high maturity shales, and solve the technical problems in the prior art that the gaseous hydrocarbon content cannot be tested and the recoverable oil, bound oil and solid hydrocarbon content cannot be distinguished.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A method for testing shale oil and gas content parameters comprises the following steps:

[0008] S1, obtaining samples: taking the core just out of the barrel as the original sample, and after measuring and recording the mass of the original sample, putting the original sample into the desorption tank of the shale gas content determination device and sealing it;

[0009] S2, sample desorption: put the desorption tank containing the original sample into the constant temperature device, so that the original sample is desorbed at a constant temperature. After the sample desorption is completed, record the total desorbed gas volume G ad , and obtain the desorption sample;

[0010] S3, sample preservation: two pieces are knocked out from the desorption sample as pyrolysis samples; one piece of pyrolysis sample is frozen in liquid nitrogen and preserved as a frozen sample; the other piece of pyrolysis sample is preserved at room temperature as a room temperature sample;

[0011] S4, sample pyrolysis: using the frozen sample and the room temperature sample for pyrolysis test, and obtaining the corresponding hydrocarbon content parameter group S at a set temperature based on the pyrolysis test;

[0012] S5, calculation of oil and gas content: the total desorbed gas volume G ad The hydrocarbon content parameter group S is combined with the corresponding oil and gas content calculation formula to obtain relevant parameters of the oil and gas content.

[0013] Preferably, the sample desorption comprises the following steps:

[0014] S21, prepare a constant temperature device, adjust the temperature in the constant temperature device to the drilling fluid circulation temperature, and then place the desorption tank containing the original sample into the constant temperature device;

[0015] S22, setting a gas content detection time based on a shale gas content measuring device;

[0016] S23, the shale gas content measuring device intermittently detects and records the desorbed gas volume of the desorption tank according to the set gas volume detection time, and obtains the corresponding desorption rate V based on the detected desorbed gas volume 解 ;

[0017] S24, determine the desorption rate V 解 Is it less than the minimum allowed rate V t ; If not, return to S23, if so, end sample desorption;

[0018] S25, using the shale gas content measuring device to detect and record the total desorbed gas volume G ad ;

[0019] S26, opening the desorption tank, and taking out the desorbed core as a desorption sample.

[0020] Preferably, in S22, setting the gas volume detection time includes: setting the shale gas content measuring device to count once every 5 minutes in the first hour of sample desorption, once every 10 minutes in the second hour, once every 15 minutes in the third hour, and once every 30 minutes after the third hour.

[0021] Preferably, in S23, the minimum rate V is allowed t 3cm 3 / 30min.

[0022] Preferably, during the pyrolysis of the sample, the pyrolysis test comprises the following steps:

[0023] S41, prepare a pyrolyzer and set working parameters of the pyrolyzer, including pyrolysis temperature and constant temperature time, that is, the constant temperature times t1, t2, t3, and t4 correspond to each other at formation temperature, 350°C, 450°C, and 600°C, respectively;

[0024] S42, after crushing the two pyrolysis samples, take a part of each and put them into the pyrolysis instrument for pyrolysis, and record the hydrocarbon content parameter group S during the pyrolysis process; the hydrocarbon content parameter group S includes the hydrocarbon contents S0, S1 and S2 measured at the formation temperature, 350°C, 450°C and 600°C at the corresponding constant temperatures t1, t2, t3 and t4 of the frozen samples. 1-1 , S 1-2 , S2, and the hydrocarbon content S0 of the normal temperature sample at formation temperature, 350℃, 450℃ and 600℃, corresponding to constant temperature t1, t2, t3, and t4 * , S 1-1 * , S 1-2 * 、S2 * ;

[0025] S43, mixing the remaining frozen sample powder and the room temperature sample powder in S42, and mixing them evenly to obtain a mixed sample;

[0026] S44, taking the mixed sample and loading it into a Soxhlet extractor, using dichloromethane to perform oil washing on the mixed sample, and using the mixed sample after the oil washing as extraction sample I;

[0027] S45, placing the extracted sample I in an oven to completely evaporate the dichloromethane in the extracted sample I to obtain an extracted sample II;

[0028] S46, take the extracted sample II and put it into the pyrolyzer for pyrolysis, and record the pyrolysis gas volume parameters during the pyrolysis process, that is, record the hydrocarbon content S0', S0' measured at the formation temperature, 350℃, 450℃ and 600℃, corresponding to the constant temperature t1, t2, t3, t4 1-1 '、S 1-2 ', S2', and the hydrocarbon content S0', S 1-1 '、S 1-2 ', S2' are added to the hydrocarbon content parameter group S.

[0029] Preferably, in S41, setting the working parameters of the pyrolyzer also includes setting the heating rate, and the heating rate is 50° C. / min.

[0030] Preferably, in S41, t1=t2=t3=1 min, t4=2 min.

[0031] Preferably, the oil and gas content calculation includes gas content calculation, and the gas content calculation includes the following steps:

[0032] S51, based on formula G ls =V lost / m t Gain loss G ls ; Among them, V lost is the volume of lost gas, determined by USBM direct method;

[0033] S52, based on the hydrocarbon content S0 of the frozen sample in S42, combined with the calorific value conversion relationship G S0 = S0 / 0.717; where the hydrocarbon content S0 is also the thermally released gaseous hydrocarbon content. According to the aforementioned calorific value conversion relationship, the thermally released gaseous hydrocarbon content is converted into the natural gas content G S0 ;

[0034] S53, according to the total desorbed gas volume G ad , gas loss G ls and natural gas content G S0 Obtain the gas content G in the rock, that is, G = G S0 +G ad +G ls .

[0035] Preferably, the oil and gas content calculation includes obtaining the recoverable oil volume S y , that is, S y =S 1-1 .

[0036] Preferably, the bound oil content S is obtained by calculating the oil and gas content s , that is, S s =S 1-2 * +S2* -S2'.

[0037] Preferably, the calculation of the oil and gas content includes calculating the gas-oil ratio GOR, that is, GOR=(G ad+ G ls+ G S0 ) / (S y +S s ).

[0038] Preferably, the oil and gas content calculation includes obtaining the solid hydrocarbon content S g , that is, S g =S2'.

[0039] Beneficial technical effects brought by the present invention:

[0040] 1. This technical solution combines the gas content test and rock pyrolysis experimental principles to develop a set of shale oil and gas content test methods. According to the characteristics of the substances contained in the core, this method develops a step-by-step process of sample desorption, sample preservation and sample pyrolysis. Based on this, the oil and gas content in medium-to-high maturity shale oil and gas reservoir samples can be tested simultaneously. Compared with the existing technology, this technical solution considers the issues more comprehensively and can ensure that the test results are accurate and reliable.

[0041] 2. This technical solution can obtain the gas content and oil content at the same time. Based on this, the gas-oil ratio can be further obtained to provide an evaluation basis for the evaluation of the mobility of reservoir crude oil.

[0042] 3. The present invention avoids the escape of light components of crude oil contained in medium-high maturity samples in a conventional (normal temperature) indoor environment and during the sample crushing process, making the oil content analysis results more realistic, thereby greatly improving the accuracy of oil content determination in medium-high maturity samples.

[0043] 4. The present invention uses the evaporation and cracking temperatures of crude oils in different occurrence states and hydrocarbons of different components to set the pyrolysis experimental temperature ladder, and calculates the actual recoverable oil content, adsorbed oil content and solid hydrocarbon content in the sample, which can provide more effective evaluation parameters for the optimization of favorable shale oil reservoir sections and resource calculation.

[0044] 5. The present invention obtains frozen samples, room temperature samples and extracted samples, conducts pyrolysis experiments on samples of the same depth with different preservation, sample preparation and pre-treatment methods, and establishes calculation formulas for recoverable oil content, bound oil content and solid hydrocarbon content according to the occurrence of recoverable oil, bound oil and solid hydrocarbons under different sample experimental conditions. The formulas can be more accurate than the values ​​obtained under one sample experimental condition.

[0045] 6. According to the law of hydrocarbon emission, the present invention establishes a correction formula for conventional pyrolysis parameters by fitting the parameter values ​​of frozen samples and room temperature samples during rock pyrolysis through linear curve fitting, calculates the content of various parameters of conventional sample preparation samples before hydrocarbon emission, and uses the content to calculate the recoverable oil content, which can reduce the number of frozen sample preparation samples and the test time, while ensuring the accuracy of the calculation of recoverable oil content. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a preferred implementation flow chart of this technical solution. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0048] Therefore, the following detailed description of the invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] This example discloses a method for testing shale oil and gas content parameters, which, as a preferred embodiment of the present invention, comprises the following steps:

[0051] S1, get the sample: take the core just out of the tube as the original sample, and record the mass m of the original sample in the measurement t Finally, the original sample is placed in the desorption tank of the shale gas content measuring device and sealed. In this process, the length of the original sample is determined according to the capacity size of the desorption tank. For example, according to the desorption tank currently used, the length of the original sample can be controlled at 25±5cm.

[0052] S2, sample desorption: put the desorption tank containing the original sample into the constant temperature device, so that the original sample is desorbed at a constant temperature. After the sample desorption is completed, record the total desorbed gas volume G ad (Unit: cm 3 / g), and obtain the desorption sample (i.e. the solid matter remaining in the desorption tank). ad =V ad / m t , V ad represents the desorbed gas volume under standard conditions (20°C, 0.101325MPa), and V ad =(293.15P m×V d ) / [0.101325×(273.15+T m )]; P m Indicates atmospheric pressure, V d represents the desorbed gas volume, T m Indicates the ambient temperature.

[0053] S3, sample preservation: two pieces are knocked out from the desorption sample as pyrolysis samples; one piece of the pyrolysis sample is frozen in liquid nitrogen (to lock the dispersible substances in the desorption sample) as a frozen sample; the other piece of the pyrolysis sample is stored at room temperature as a room temperature sample.

[0054] S4, sample pyrolysis: the frozen sample and the room temperature sample are used for pyrolysis test, and based on the pyrolysis test at a set temperature, a corresponding hydrocarbon content parameter group S is obtained. Specifically, the pyrolysis gas volume parameter in the hydrocarbon content parameter group S is specifically a hydrocarbon content parameter.

[0055] S5, calculation of oil and gas content: the total desorbed gas volume G ad The hydrocarbon content parameter group S is combined with the corresponding oil and gas content calculation formula to obtain relevant parameters of the oil and gas content.

[0056] Example 2

[0057] This example discloses a method for testing shale oil and gas content parameters. As a preferred embodiment of the present invention, in Example 1, sample desorption includes the following steps:

[0058] S21, prepare a constant temperature device, adjust the temperature in the constant temperature device to the drilling fluid circulation temperature, and then place the desorption tank containing the original sample into the constant temperature device.

[0059] S22, desorption refers to the reverse process of adsorption, which is the operation of separating the absorbed gas from the absorbent (corresponding to the core in the technical solution). During the desorption process, as the gas adsorbed in the core decreases, the desorption rate will gradually decrease. Based on this, it can be determined whether the desorption has been completed according to the method of obtaining the desorption rate. The simplest way to obtain the rate is to obtain the desorbed gas volume in different time periods. Based on this, the gas volume detection time can be set by the shale gas gas content determination device.

[0060] S23, the shale gas content measuring device intermittently detects and records the desorbed gas volume of the desorption tank according to the set gas volume detection time, and obtains the corresponding desorption rate V based on the detected desorbed gas volume 解 .

[0061] S24, due to the special structure inside the core, there is always some gas inside, so the desorption rate V 解This makes it difficult to determine whether desorption has been completed. To address this, a minimum allowable rate V can be preset. t , determine the desorption rate V 解 Is it less than the minimum allowed rate V t ; If not, return to S23, if so, the sample desorption is terminated.

[0062] S25, after the sample desorption is completed, the total desorbed gas volume G is detected and recorded using a shale gas content measuring device. ad , more specifically, the total desorbed gas volume G ad It is the volume of natural gas contained in the core per unit mass under standard conditions (20°C, 0.101325MPa), that is, the total desorbed gas volume G ad The unit is cm 3 / g.

[0063] S26, opening the desorption tank, and taking out the desorbed core as a desorption sample.

[0064] Example 3

[0065] This example discloses a method for testing shale oil and gas content parameters. As a preferred embodiment of the present invention, in Example 1, sample desorption includes the following steps:

[0066] This example discloses a method for testing shale oil and gas content parameters. As a preferred embodiment of the present invention, in Example 1, sample desorption includes the following steps:

[0067] S21, prepare a constant temperature device, adjust the temperature in the constant temperature device to the drilling fluid circulation temperature, and then place the desorption tank containing the original sample into the constant temperature device.

[0068] S22, setting the gas volume detection time through the shale gas content measuring device. In particular, based on the characteristics of the desorption rate becoming slower and slower, it is not very meaningful to perform gas volume detection multiple times in a short period of time in the later stage of desorption, and it will also increase the amount of data processing. Based on this, the characteristics of the desorption rate becoming slower and slower are combined, and the gas volume detection time is set specifically as follows: the shale gas content measuring device is set to count once every 5 minutes in the first hour of sample desorption, once every 10 minutes in the second hour, once every 15 minutes in the third hour, and once every 30 minutes after the third hour.

[0069] S23, the shale gas content measuring device intermittently detects and records the desorbed gas volume of the desorption tank according to the set gas volume detection time, and obtains the corresponding desorption rate V based on the detected desorbed gas volume 解 , desorption rate V 解 It can be the average desorption rate in each counting time interval.

[0070] S24, due to the special structure inside the core, there is always some gas inside, so the desorption rate V 解 This makes it difficult to determine whether desorption has been completed. To address this, a minimum allowable rate V can be preset. t , determine the desorption rate V 解 Is it less than the minimum allowed rate V t If not, return to S23, if so, the sample desorption is terminated; wherein the minimum rate V t 3cm 3 / 30min.

[0071] S25, after the sample desorption is completed, the volume of natural gas contained in the core per unit mass under standard conditions (20°C, 0.101325MPa) is detected and recorded using a shale gas content measuring device, i.e., the total desorbed gas volume G ad , unit is cm 3 / g.

[0072] S26, opening the desorption tank, and taking out the desorbed core as a desorption sample.

[0073] Example 4

[0074] This example discloses a method for testing shale oil and gas content parameters, which, as a preferred embodiment of the present invention, comprises the following steps:

[0075] S1, get the sample: take the core just out of the tube as the original sample, and record the mass m of the original sample in the measurement t Finally, the original sample is placed in the desorption tank of the shale gas content measuring device and sealed.

[0076] S2, sample desorption: put the desorption tank containing the original sample into the constant temperature device, so that the original sample is desorbed at a constant temperature. After the sample desorption is completed, record the volume of natural gas contained in the core per unit mass under standard conditions (20℃, 0.101325MPa), that is, the total desorbed gas volume G ad (Unit: cm 3 / g).

[0077] S3, sample preservation: knock two pieces from the desorption sample as pyrolysis samples; one piece of the pyrolysis sample is frozen in liquid nitrogen as a frozen sample to ensure that the dispersible substances are completely locked in the desorption sample; the other piece of the pyrolysis sample is stored at room temperature as a room temperature sample.

[0078] S4, sample pyrolysis: the frozen sample and the room temperature sample are used for pyrolysis test, and based on the pyrolysis test at a set temperature, a corresponding hydrocarbon content parameter group S is obtained. Specifically, the pyrolysis gas volume parameter in the hydrocarbon content parameter group S is specifically a hydrocarbon content parameter.

[0079] The pyrolysis test includes the following steps:

[0080] S41, prepare the pyrolyzer, and set the working parameters of the pyrolyzer, including the pyrolysis temperature and the constant temperature time, that is, the constant temperature times t1, t2, t3, and t4 correspond to each other at the formation temperature (that is, the temperature of the bottom layer where the original sample was originally located), 350°C, 450°C, and 600°C, respectively; specifically, t1=t2=t3=1min, t4=2min, that is, the internal temperature in the pyrolyzer is kept constant for t1=1min after reaching the formation temperature, the internal temperature in the pyrolyzer is kept constant for t2=1min after reaching 350°C, the internal temperature in the pyrolyzer is kept constant for t3=1min after reaching 450°C, and the internal temperature in the pyrolyzer is kept constant for t4=2min after reaching 600°C.

[0081] S42, after the two pyrolysis samples are crushed (below 100 mesh), a portion (100±5 mg) of each sample is taken and placed in a pyrolyzer for pyrolysis (specifically, the frozen sample is sealed and crushed in a frozen sealed crusher, and the room temperature sample is crushed in a non-sealed crushing method), and the hydrocarbon content parameter group S is recorded during the pyrolysis process; the hydrocarbon content parameter group S includes the hydrocarbon content parameters of the frozen sample and the hydrocarbon content parameters of the room temperature sample.

[0082] Hydrocarbon content parameters for frozen samples include:

[0083] S0: During the pyrolysis process of the frozen sample, the pyrolysis hydrocarbon content per unit mass of the core detected by the pyrolyzer after the pyrolyzer reaches the formation temperature and is kept at a constant temperature for t1, in mg / g;

[0084] S 1-1 : During the pyrolysis of frozen samples, the pyrolysis hydrocarbon content per unit mass of the core is detected by the pyrolyzer after the temperature reaches 350°C and the temperature is kept constant for t2. The hydrocarbon content here is the hydrocarbon content pyrolyzed during the process of heating from the formation temperature to 350°C and keeping the temperature constant for t2, and the unit is mg / g;

[0085] S 1-2 : During the pyrolysis of frozen samples, the pyrolysis hydrocarbon content per unit mass of the core is detected after the pyrolyzer reaches 450°C and keeps the temperature constant for t3. The hydrocarbon content here refers to the pyrolysis hydrocarbon content during the process of heating from 350°C to 450°C and keeping the temperature constant for t3, in mg / g;

[0086] S2: During the pyrolysis process of the frozen sample, the pyrolyzer detects the hydrocarbon content per unit mass of the core after the temperature reaches 600°C and is maintained at a constant temperature of t4. The hydrocarbon content here is the hydrocarbon content pyrolyzed in the process of heating from 450°C to 600°C and maintaining a constant temperature of t3, and the unit is mg / g.

[0087] Hydrocarbon content parameters for ambient temperature samples include:

[0088] S0 * : During the pyrolysis process of the room temperature sample, the pyrolysis hydrocarbon content per unit mass of the core detected by the pyrolyzer after the pyrolyzer reaches the formation temperature and maintains a constant temperature t1, in mg / g;

[0089] S 1-1 * : During the pyrolysis of room temperature samples, the pyrolysis hydrocarbon content per unit mass of the core is detected after the pyrolyzer reaches 350℃ and maintains a constant temperature of t2. The hydrocarbon content here is the hydrocarbon content of the pyrolysis in the process of heating from the formation temperature to 350℃ and maintaining a constant temperature of t2, and the unit is mg / g;

[0090] S 1-2 * : During the pyrolysis of room temperature samples, the pyrolysis hydrocarbon content per unit mass of the core is detected after the pyrolyzer reaches 450°C and maintains a constant temperature of t3. The hydrocarbon content here refers to the pyrolysis hydrocarbon content during the process of heating from 350°C to 450°C and maintaining a constant temperature of t3, in mg / g;

[0091] S2 * :During the pyrolysis process of room temperature samples, the pyrolyzer detects the hydrocarbon content per unit mass of the core after reaching 600℃ and maintaining the constant temperature at t4. The hydrocarbon content here refers to the hydrocarbon content pyrolyzed in the process of heating from 450℃ to 600℃ and maintaining the constant temperature at t3, and the unit is mg / g.

[0092] S43, mixing the remaining frozen sample powder and the room temperature sample powder in S42, and obtaining a mixed sample after mixing evenly.

[0093] S44, take the mixed sample (100±5mg) and put it into the Soxhlet extractor, use dichloromethane to extract and wash the mixed sample (extraction treatment), and use the mixed sample after the oil washing treatment as the extraction sample I. The extraction can be terminated when the fluorescence of the solvent dropped into the mixed sample is below level 3.

[0094] S45, placing the extracted sample I in an oven to completely evaporate the dichloromethane in the extracted sample I to obtain an extracted sample II;

[0095] S46, take the extracted sample II and put it into the pyrolyzer for pyrolysis, and record the pyrolysis gas volume parameters during the pyrolysis process, that is, record the hydrocarbon content S0', S0' measured at the formation temperature, 350℃, 450℃ and 600℃, corresponding to the constant temperature t1, t2, t3, t4 1-1 '、S 1-2 ', S2', and the hydrocarbon content S0', S 1-1 '、S 1-2 ', S2' are added to the hydrocarbon content parameter group S. Where:

[0096] S0': The content of hydrocarbons per unit mass of the core that is pyrolyzed when the pyrolyzer reaches the formation temperature and is kept at a constant temperature for t1 during the pyrolysis of the extracted sample II, in mg / g;

[0097] S 1-1 ': The hydrocarbon content of the unit mass of the core detected by the pyrolysis instrument after the pyrolyzer reaches 350℃ and keeps the temperature constant for t2 during the pyrolysis of the extracted sample II. The hydrocarbon content here is the hydrocarbon content of the pyrolysis in the process of heating from the formation temperature to 350℃ and keeping the temperature constant for t2, in mg / g;

[0098] S 1-2 ': The hydrocarbon content of the unit mass of the core detected by the pyrolysis instrument after the pyrolysis instrument reaches 450℃ and maintains the constant temperature t3 during the pyrolysis of the extracted sample II. The hydrocarbon content here refers to the hydrocarbon content of the pyrolysis during the process of heating from 350℃ to 450℃ and maintaining the constant temperature t3, in mg / g;

[0099] S2': During the pyrolysis process of the extracted sample II, the pyrolysis hydrocarbon content per unit mass of the core is detected by the pyrolyzer after the pyrolyzer reaches 600°C and maintains a constant temperature of t4. The hydrocarbon content here is the pyrolysis hydrocarbon content in the process of heating from 450°C to 600°C and maintaining a constant temperature of t3, and the unit is mg / g.

[0100] S5, calculation of oil and gas content: the total desorbed gas volume G ad The hydrocarbon content parameter group S is combined with the corresponding oil and gas content calculation formula to obtain the relevant parameters of the oil and gas content. It should be noted that the above content describes that the hydrocarbon content parameter group S includes hydrocarbon content parameters S0, S 1-1 , S 1-2 , S2, S0 * , S 1-1 * , S 1-2 * 、S2 * , S0', S 1-1 '、S 1-2', S2', these data are recorded to ensure the integrity of the pyrolysis test data, to facilitate understanding of the specific conditions of sample pyrolysis, and to facilitate later analysis of the pyrolysis properties of the core. Not all hydrocarbon content parameters are required to participate in the calculation of relevant parameters obtained by this technical solution.

[0101] Further, according to the change of the pyrolysis temperature of the pyrolyzer required to be set in S41, it can be seen that the pyrolyzer has a heating process. Based on this, setting the working parameters of the pyrolyzer also includes setting the heating rate, and the heating rate is 50°C / min.

[0102] Example 5

[0103] This example discloses a method for testing shale oil and gas content parameters. As a preferred embodiment of the present invention, in Example 4, the oil and gas content calculation includes the gas content calculation, and the gas content calculation includes the following steps:

[0104] S51, based on the formula Gls = V lost / m t Gain loss G ls ; Among them, V lost The lost gas volume is determined by the USBM (United States Bureau of Mines) direct method, with the accumulated desorption volume under standard conditions as the ordinate and the square root of the desorption time as the abscissa. The absolute value of the intercept of the reverse extension line and the ordinate axis in the graph of desorption gas volume and the square root of desorption time is defined as the lost gas.

[0105] S52, based on the hydrocarbon content S0 of the frozen sample in S42, combined with the calorific value conversion relationship G S0 = S0 / 0.717; where the hydrocarbon content S0 is also the thermally released gaseous hydrocarbon content. According to the aforementioned calorific value conversion relationship, the thermally released gaseous hydrocarbon content is converted into the natural gas content G S0 , unit is cm 3 / g. It should be noted that 0.717kg / m 3 is the density of methane at normal temperature and pressure, and S0 is mainly composed of methane gas, so the methane gas density is used here instead of the S0 gaseous hydrocarbon density.

[0106] S53, according to the total desorbed gas volume G ad , gas loss G ls and natural gas content G S0 Obtain the gas content G in the rock, that is, G = G S0 +G ad +G ls , unit is cm 3 / g.

[0107] Furthermore, the calculation of oil and gas content includes obtaining the recoverable oil volume S y , that is, S y =S 1-1 .

[0108] Furthermore, the bound oil content S is obtained by calculating the oil and gas content s , that is, S s =S 1-2 * +S2 * -S2'.

[0109] Furthermore, the calculation of oil and gas content includes the calculation of gas-oil ratio GOR, that is, GOR = (G ad+ G ls+ G S0 ) / (S y +S s ).

[0110] Furthermore, the calculation of oil and gas content includes obtaining the solid hydrocarbon content S g , that is, S g =S2'.

[0111] The principles of the above calculation design include: shale oil in different occurrence states has different molecular thermal volatility. For medium-high maturity shale oil reservoirs, the crude oil produced is mainly light-medium oil components, and the corresponding evaporation temperature is between the formation temperature and 350°C. At the same time, the chromatographic characteristics of thermally released hydrocarbons in this temperature range are similar to those of crude oil. Therefore, S 1-1 Characterize the recoverable oil content. Bound oil is mostly large molecular heavy hydrocarbons, colloidal asphaltene components, and light-medium oil adsorbed in the micro-nano pores of kerogen and clay minerals. Its evaporation, cracking and thermal desorption temperatures are mainly between 350℃-450℃, but the cracking temperature of such large molecular bound oils as high wax hydrocarbons adsorbed in the micro-nano pores of kerogen and clay minerals is above 450℃. Therefore, the principle of like dissolves like is adopted, and dichloromethane is used to extract the kerogen (solid hydrocarbons) in the remaining samples of the light-heavy oil components in the sample. The degradation and hydrocarbon generation temperature of kerogen needs to be above 450℃, so S2' characterizes the solid hydrocarbon content. Therefore, the kerogen and bound hydrocarbon content above 450℃ can be distinguished, S 1-2 * +S2 * - S2' is the bound oil content.

[0112] Example 6

[0113] This example discloses a method for testing shale oil and gas content parameters. As a preferred embodiment of the present invention, in Example 5, hundreds of original samples may be collected in a wellbore. If each original sample involves a pyrolysis test of a frozen sample, the workload of the shale oil and gas content test will be greatly increased. Therefore, in order to reduce the workload, some (such as 10) original samples are selected to participate in the pyrolysis test of the frozen sample, and then the parameter values ​​(hydrocarbon content parameters) of the same temperature section obtained by the frozen pyrolysis and room temperature pyrolysis experiments are used to make a correlation scatter plot, and then a one-dimensional linear relationship is used to fit the scatter points to establish a correction formula for the room temperature pyrolysis parameters; S0 can be obtained according to the room temperature pyrolysis experiment (pyrolysis test of room temperature samples). * , S 1-1 * , S 1-2 * 、S2 * , S0 * , S 1-1 * , S 1-2 * 、S2 * Substituting the correction formula into the above formula, the corresponding frozen pyrolysis (pyrolysis of frozen samples) values ​​S0, S 1-1 , S 1-2 , S2.

Claims

1. A method for testing shale oil and gas content parameters, characterized in that: The following steps are involved: S1, get the sample: take the core just out of the tube as the original sample, and record the mass m of the original sample in the measurement t Afterwards, the original sample is placed in a desorption tank of a shale gas content determination device and sealed; S2, sample desorption: put the desorption tank containing the original sample into the constant temperature device, so that the original sample is desorbed at a constant temperature. After the sample desorption is completed, record the total desorbed gas volume G ad , and obtain the desorption sample; S3, sample preservation: two pieces are knocked out from the desorption sample as pyrolysis samples; one piece of pyrolysis sample is frozen in liquid nitrogen and preserved as a frozen sample; the other piece of pyrolysis sample is preserved at room temperature as a room temperature sample; S4, sample pyrolysis: using the frozen sample and the room temperature sample for pyrolysis test, and obtaining the corresponding hydrocarbon content parameter group S at a set temperature based on the pyrolysis test; S5, calculation of oil and gas content: the total desorbed gas volume G ad The hydrocarbon content parameter group S is combined with the corresponding oil and gas content calculation formula to obtain relevant parameters of the oil and gas content.

2. A method for testing shale oil and gas content parameters as claimed in claim 1, characterized in that: The sample desorption comprises the following steps: S21, prepare a constant temperature device, adjust the temperature in the constant temperature device to the drilling fluid circulation temperature, and then place the desorption tank containing the original sample into the constant temperature device; S22, setting a gas content detection time based on a shale gas content measuring device; S23, the shale gas content measuring device intermittently detects and records the desorbed gas volume of the desorption tank according to the set gas volume detection time, and obtains the corresponding desorption rate V based on the detected desorbed gas volume 解 ; S24, determine the desorption rate V 解 Is it less than the minimum allowed rate V t ; If not, return to S23, if so, end sample desorption; S25, using the shale gas content measuring device to detect and record the total desorbed gas volume G ad ; S26, opening the desorption tank, and taking out the desorbed core as a desorption sample.

3. A method for testing shale oil and gas content parameters as claimed in claim 2, characterized in that: In S22, setting the gas volume detection time includes: setting the shale gas content measuring device to count once every 5 minutes in the first hour of sample desorption, once every 10 minutes in the second hour, once every 15 minutes in the third hour, and once every 30 minutes after the third hour.

4. A method for testing shale oil and gas content parameters as claimed in claim 2, characterized in that: In S23, the minimum rate V is allowed t 3cm 3 / 30min.

5. The method for testing shale oil and gas content parameters according to claim 1, characterized in that: During the pyrolysis of the sample, the pyrolysis test includes the following steps: S41, prepare a pyrolyzer and set working parameters of the pyrolyzer, including pyrolysis temperature and constant temperature time, that is, the constant temperature times t1, t2, t3, and t4 correspond to each other at formation temperature, 350°C, 450°C, and 600°C, respectively; S42, after crushing the two pyrolysis samples, take a part of each and put them into the pyrolysis instrument for pyrolysis, and record the hydrocarbon content parameter group S during the pyrolysis process; the hydrocarbon content parameter group S includes the hydrocarbon contents S0, S1 and S2 measured at the formation temperature, 350°C, 450°C and 600°C at the corresponding constant temperatures t1, t2, t3 and t4 of the frozen samples. 1-1 , S 1-2 , S2, and the hydrocarbon content S0 of the normal temperature sample at formation temperature, 350℃, 450℃ and 600℃, corresponding to constant temperature t1, t2, t3, and t4 * , S 1-1 * , S 1-2 * 、S2 * ; S43, mixing the remaining frozen sample powder and the room temperature sample powder in S42, and mixing them evenly to obtain a mixed sample; S44, taking the mixed sample and loading it into a Soxhlet extractor, using dichloromethane to perform oil washing on the mixed sample, and using the mixed sample after the oil washing as extraction sample I; S45, placing the extracted sample I in an oven to completely evaporate the dichloromethane in the extracted sample I to obtain an extracted sample II; S46, take the extracted sample II and put it into the pyrolyzer for pyrolysis, and record the pyrolysis gas volume parameters during the pyrolysis process, that is, record the hydrocarbon content S0', S0' measured at the formation temperature, 350℃, 450℃ and 600℃, corresponding to the constant temperature t1, t2, t3, t4 1-1 '、S 1-2 ', S2', and the hydrocarbon content S0', S 1-1 '、S 1-2 ', S2' are added to the hydrocarbon content parameter group S.

6. A method for testing shale oil and gas content parameters as claimed in claim 5, characterized in that: In the S41, setting the working parameters of the pyrolyzer also includes setting the heating rate, and the heating rate is 50°C / min.

7. A method for testing shale oil and gas content parameters as claimed in claim 5, characterized in that: In the S41, t1=t2=t3=1min, t4=2min.

8. The method for testing shale oil and gas content parameters according to claim 5, characterized in that: The oil and gas content meter The calculation includes the calculation of gas content, and the calculation of gas content includes the following steps: S51, based on formula G ls =V lost / m t Gain loss G ls ; Among them, V lost is the volume of lost gas, determined by USBM direct method; S52, based on the hydrocarbon content S0 of the frozen sample in S42, combined with the calorific value conversion relationship G S0 = S0 / 0.717; wherein the hydrocarbon content S0 is also the thermally released gaseous hydrocarbon content. According to the aforementioned calorific value conversion relationship, the thermally released gaseous hydrocarbon content is converted into the natural gas content G S0 ; S53, according to the total desorbed gas volume G ad , gas loss G ls and natural gas content G S0 Obtain the gas content G in the rock, that is, G = G S0 +G ad +G ls .

9. A method for testing shale oil and gas content parameters as claimed in claim 5, characterized in that: The oil and gas content calculation includes obtaining the recoverable oil volume S y , that is, S y =S 1-1 .

10. A method for testing shale oil and gas content parameters as claimed in claim 9, characterized in that: The bound oil content S is obtained by calculating the oil and gas content s , that is, S s =S 1-2 * +S2 * -S2'.

11. A method for testing shale oil and gas content parameters as claimed in claim 10, characterized in that: The calculation of gas and oil content includes the calculation of gas-oil ratio GOR, that is, GOR=(G ad+ G ls+ G S0 ) / (S y +S s ).

12. A method for testing shale oil and gas content parameters as claimed in claim 11, characterized in that: The oil and gas content calculation includes obtaining the solid hydrocarbon content S g , that is, S g =S2'.

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