Method and device for eliminating coal seam interference in accurate identification of gas well reservoirs

Abstract

The present application relates to gas well reservoir identification method technical field, it is a kind of gas well reservoir accurate identification method and device for eliminating coal seam interference, including using while drilling gamma curve, resistivity curve and lithology logging coal content ratio, confirm the existence of coal seam;Dynamic influence factor is calculated;Based on gas logging data correction formula, obtain the gas logging correction value of any depth point, based on resistivity correction formula, obtain correction resistivity;Combining gas logging correction value, correction resistivity, gas logging humidity ratio and acoustic time difference, distinguish reservoir type.The present application first corrects gas logging data and logging resistivity, eliminates the influence of coal seam on the gas logging data and the resistivity data, effectively removes the abnormal interference of coal seam on gas logging data and logging data, then combines the gas logging correction value, correction resistivity obtained after correction, gas logging humidity ratio and acoustic time difference, comprehensively determines whether the target layer is gas layer, and the present application improves the precision and efficiency of gas layer identification.

Description

Technical Field

[0001] This invention relates to the technical field of gas well reservoir identification methods, and is a method and apparatus for eliminating coal seam interference in the accurate identification of gas well reservoirs. Background Technology

[0002] In oil and gas exploration and development, accurate identification of gas-bearing reservoirs (especially sandstone reservoirs) is fundamental to evaluating reservoir productivity, optimizing well completion plans, and formulating development strategies. Gas logging (hydrocarbon gas detection) and conventional logging (such as resistivity, acoustic, density, neutron, etc.) are the core methods for reservoir identification and evaluation.

[0003] Coal seams are typically rich in adsorbed methane gas. During drilling, when a coal seam is encountered, the breaking of coal cuttings releases a large amount of methane, causing an abnormally high increase in total hydrocarbon values ​​(referred to as gas logging values) and component values ​​(C1) on gas logging. This "false anomaly" is easily confused with the responses of sandstone gas layers below or above, leading to the misinterpretation of the coal seam as a gas layer (false positive), masking weak indications of the underlying sandstone gas layer (false negative), and distortion of gas logging interpretation parameters (such as moisture ratio, equilibrium ratio, hydrocarbon slope, etc.), making it impossible to accurately determine the reservoir fluid properties. Coal seams also exhibit characteristic responses on conventional logging curves (such as high gamma, low resistivity, high neutron porosity, high sonic transit time, etc.). When coal seams and sandstone reservoirs overlap in terms of physical properties or gas content (e.g., low-resistivity gas layers or low-porosity gas layers are close to coal seams), their logging responses overlap or are similar, increasing the difficulty and uncertainty of identifying gas layers using a single logging curve.

[0004] The following are relevant documents on eliminating coal seam interference during reservoir identification:

[0005] Qiao Zhonglin et al. (Qiao Zhonglin. A method to remove the influence of coal seams on reservoir prediction in the Binchang area [J]. Frontiers in Marine Geology, 2018, 34(11):66-71) weakened the shielding effect of coal seams on the reflected waves of underlying strata and the interference of inter-layer multiple waves to a certain extent by performing wavelet decomposition and waveform decomposition on the original seismic data volume. The method of eliminating coal seam interference in this literature is different from that of our technique, and the data processed is seismic data volume.

[0006] Patent application CN116047605A discloses a seismic imaging correction method to eliminate the influence of coal seams. It constructs a geological model of the target area using actual well logging data, performs forward modeling on the geological model to obtain the relationship between the corresponding two-way travel time (BLT) and formation velocity, and uses this relationship to correct the relationship between the BLT and formation velocity obtained from the seismic reflection data. Finally, it adjusts the seismic reflection data using the corrected BLT and formation velocity relationship to correct the seismic imaging results. This patent application uses a different method to eliminate coal seam interference than this method, and its purpose is to correct the seismic reflection data.

[0007] Therefore, there is an urgent need for a method that can quantitatively and automatically identify and remove the abnormal effects of coal seams on gas logging and well logging data, so as to improve the accuracy and efficiency of gas seam identification. Summary of the Invention

[0008] This invention provides a method and apparatus for eliminating coal seam interference in the accurate identification of gas well reservoirs, overcoming the shortcomings of the prior art, and effectively removing abnormal interference from coal seams on gas logging and well logging data.

[0009] One of the technical solutions of this invention is achieved through the following measures: a method for accurately identifying and eliminating coal seams in gas well reservoirs, comprising:

[0010] The existence of coal seams is confirmed by using the gamma ray curve, resistivity curve and cuttings ratio in cuttings logging. If coal seams exist, the top and bottom depths of the coal seams are extracted, and the center depth and thickness of the coal seams are calculated based on the top and bottom depths.

[0011] The coal rank coefficient is calculated based on the coal rank parameters of the coal seam sample. The drilling time value at any depth point is extracted. The attenuation factor is calculated according to the exponential attenuation law using the vertical distance between the arbitrary depth point and the center of the coal seam. The dynamic influence factor is calculated based on the coal seam thickness, coal rank coefficient, drilling time value at any depth point and attenuation factor.

[0012] Based on the gas measurement data correction formula, the gas measurement correction value at any depth point is obtained. The gas measurement data correction formula is as follows:

[0013]

[0014] In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point; TG raw (d) represents the original gas measurement value at any depth point; γ represents the stripping coefficient; IF coal (d) represents the dynamic influencing factor; d represents any depth point.

[0015] The corrected resistivity is obtained based on the resistivity correction formula, and the corrected resistivity is as follows:

[0016]

[0017] In the formula, RT sand (d) represents the corrected resistivity at any depth point; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; RT log (d) represents the resistivity measurement at any depth point; RT coal d represents the median resistivity of the coal seam, and d represents any depth point;

[0018] The reservoir type is determined by combining the gas measurement correction value, correction resistivity, gas measurement humidity ratio, and acoustic transit time.

[0019] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions:

[0020] The above-mentioned use of drilling gamma ray curves, resistivity curves, and cuttings logging coal cuttings ratio to confirm the existence of coal seams specifically includes:

[0021] A coal seam exists when the following conditions are simultaneously met by the drilling gamma ray curve, resistivity curve, and cuttings logging coal cuttings ratio:

[0022] The GR value in the gamma-ray disc of the continuous section is greater than 150 API; the resistivity value of the resistivity curve of the continuous section is <10 Ω·m; and the proportion of cuttings in the cuttings logging of the continuous section is ≥70%.

[0023] The above coal rank coefficient is calculated using the following formula:

[0024]

[0025] In the formula, α represents the coal rank coefficient; Ro represents the coal rank parameter.

[0026] The above attenuation factor is calculated using the following formula:

[0027]

[0028] In the formula, A represents the attenuation factor; β is the attenuation constant; d-Dc represents the vertical distance between any depth point and the center of the coal seam; d represents any depth point; and Dc represents the depth of the coal seam center.

[0029] The above dynamic impact factors are calculated using the following formula:

[0030]

[0031] In the formula, IF coal (d) represents the dynamic influencing factor; α represents the coal rank coefficient; T h Represents the coal seam thickness; ROP(d) represents the drilling time value at any depth point; A represents the attenuation factor.

[0032] The stripping coefficient in the above gas measurement data correction formula is obtained as follows:

[0033] Using the mudstone section without coal seam interference as the background section, the original gas measurement value of the background section as the y-value, and the dynamic influence factor as the x-value, data fitting is performed, and the coefficient of the x-term in the fitting formula is used as the stripping coefficient.

[0034] The proportion of coal seam volume corresponding to the distance between any of the above depth points and the nearest boundary of the coal seam is obtained by the following formula:

[0035]

[0036] In the formula, δd represents the distance between any depth point and the nearest boundary of the coal seam; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; d represents any depth point.

[0037] For sandstone, if the following four conditions are met simultaneously, the reservoir corresponding to any depth point d is determined to be a gas reservoir; otherwise, it is determined to be a non-gas reservoir.

[0038] Gas logging data: TG 校正 (d)≥2×TG bg The measured humidity ratio Wh(d) is ≤40%;

[0039] In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point d; TG bg Represents background atmospheric value;

[0040] Well logging data: ;

[0041] In the formula, RT sand (d) represents the corrected resistivity at any depth point d; AC(d) represents the acoustic transit time at any depth point d.

[0042] The second technical solution of the present invention is achieved through the following measures: an apparatus for eliminating coal seam interference in the accurate identification of gas well reservoirs as described in the first technical solution, comprising:

[0043] Coal seam identification and parameter extraction module: The existence of coal seams is confirmed by using the gamma curve, resistivity curve and cuttings ratio in cuttings logging. If a coal seam exists, the top and bottom depths of the coal seam are extracted, and the center depth and thickness of the coal seam are calculated based on the top and bottom depths.

[0044] The module for calculating dynamic impact factors calculates the coal rank coefficient based on the coal rank parameters of the coal seam sample, extracts the drilling time value at any depth point, calculates the attenuation factor according to the exponential decay law using the vertical distance between the arbitrary depth point and the center of the coal seam, and calculates the dynamic impact factor based on the coal seam thickness, coal rank coefficient, drilling time value at any depth point, and attenuation factor.

[0045] Gas measurement data correction module: Based on the gas measurement data correction formula, it obtains the gas measurement correction value at any depth point. The gas measurement data correction formula is as follows:

[0046]

[0047] In the formula, TG 校正(d) represents the atmospheric measurement correction value at any depth point; TG raw (d) represents the original gas measurement value at any depth point; γ represents the stripping coefficient; IF coal (d) represents the dynamic influencing factor; d represents any depth point.

[0048] Resistivity correction module: The corrected resistivity is obtained based on the resistivity correction formula, as shown below:

[0049]

[0050] In the formula, RT sand (d) represents the corrected resistivity at any depth point; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; RT log (d) represents the resistivity measurement at any depth point; RT coal d represents the median resistivity of the coal seam, and d represents any depth point;

[0051] Reservoir type identification module: Combines gas logging correction values, corrected resistivity, gas logging humidity ratio, and acoustic transit time to identify reservoir type.

[0052] This invention first corrects the gas logging data and resistivity data to eliminate the influence of coal seams on these data, effectively removing abnormal interference from coal seams. Then, by combining the corrected gas logging values, corrected resistivity, gas logging humidity ratio, and acoustic transit time, a comprehensive determination is made as to whether the target layer is a gas layer. This invention improves the accuracy and efficiency of gas layer identification. Field application verification shows that this invention achieves a gas layer identification efficiency of up to 94.7%. Attached Figure Description

[0053] Appendix Figure 1 This is a fitting graph of the original gas measurement values ​​and the dynamic influencing factors. Detailed Implementation

[0054] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0055] Analysis of the terms used in this application:

[0056] In this invention, the coal rank parameter refers to the vitrinite reflectance. The vitrinite reflectance of coal is the percentage of the intensity of the reflected light (λ = 546 nm) from the polished vitrinite surface under an oil immersion microscope objective relative to the intensity of the perpendicularly incident light.

[0057] The vitrinite reflectance of coal is the same as the random vitrinite reflectance of coal. The random vitrinite reflectance of coal is measured according to GB / T40485-2021 "Automatic Measurement and Image Analysis Method for Random Vitrinite Reflectance of Coal".

[0058] The determination method for total hydrocarbon value (i.e. raw gas measurement value) generally adopts gas chromatography. The principle of determination is to separate hydrocarbon compounds in the sample and perform quantitative analysis on them by gas chromatography.

[0059] The present invention will be further described below with reference to embodiments:

[0060] Example 1: A method for accurately identifying and eliminating coal seams in gas well reservoirs, comprising:

[0061] Coal seam identification and parameter extraction: The existence of coal seams is confirmed by using the gamma curve, resistivity curve and cuttings ratio in cuttings logging. If a coal seam exists, the top and bottom depths of the coal seam are extracted, and the center depth and thickness of the coal seam are calculated based on the top and bottom depths.

[0062] Calculate the dynamic influence factor: Calculate the coal rank coefficient based on the coal rank parameters of the coal seam sample, extract the drilling time value at any depth point, calculate the attenuation factor according to the exponential decay law using the vertical distance between the arbitrary depth point and the center of the coal seam, and calculate the dynamic influence factor based on the coal seam thickness, coal rank coefficient, drilling time value at any depth point and attenuation factor.

[0063] Gas logging data correction: Based on the gas logging data correction formula, the gas logging correction value at any depth point is obtained. The gas logging data correction formula is as follows:

[0064]

[0065] In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point; TG raw (d) represents the original gas measurement value at any depth point; γ represents the stripping coefficient; IF coal (d) represents the dynamic influencing factor; d represents any depth point.

[0066] Resistivity correction: The corrected resistivity is obtained based on the resistivity correction formula, as shown below:

[0067]

[0068] In the formula, RT sand (d) represents the corrected resistivity at any depth point; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; RT log (d) represents the resistivity measurement at any depth point; RTcoal d represents the median resistivity of the coal seam, and d represents any depth point;

[0069] Reservoir type identification: The reservoir type is identified by combining gas logging correction values, corrected resistivity, gas logging humidity ratio, and acoustic transit time.

[0070] Example 2: As an optimization of the above example, the existence of a coal seam is confirmed using drilling gamma ray curves, resistivity curves, and the proportion of coal cuttings in cuttings logging. If a coal seam exists, the specific steps include:

[0071] A coal seam exists when the following conditions are simultaneously met by the drilling gamma ray curve, resistivity curve, and cuttings logging coal cuttings ratio:

[0072] The GR value in the gamma-ray disc of the continuous section is greater than 150 API; the resistivity value of the resistivity curve of the continuous section is <10 Ω·m; and the proportion of cuttings in the cuttings logging of the continuous section is ≥70%.

[0073] Imaging logging is used to extract the top and bottom depths of the coal seam, and the center depth and thickness of the coal seam are calculated based on the top and bottom depths.

[0074] The depth of the coal seam center is calculated using the following formula:

[0075]

[0076] In the formula, D c D represents the depth of the coal seam center. top D represents the top depth of the coal seam; bottom Represents the bottom depth of the coal seam

[0077] Coal seam thickness is calculated using the following formula:

[0078]

[0079] In the formula, T h Represents coal seam thickness; D top D represents the top depth of the coal seam; bottom This represents the bottom depth of the coal seam.

[0080] Example 3: As an optimization of the above examples, the coal rank coefficient is calculated using the following formula:

[0081]

[0082] In the formula, α represents the coal rank coefficient; Ro represents the coal rank parameter.

[0083] Example 4: As an optimization of the above examples, the attenuation factor is calculated using the following formula:

[0084]

[0085] In the formula, A represents the attenuation factor; β is the attenuation constant (default value is 0.05m). -1 ); d-Dc represents the vertical distance between an arbitrary depth point and the center of the coal seam; d represents an arbitrary depth point; Dc represents the depth of the coal seam center.

[0086] Example 5: As an optimization of the above examples, the dynamic influence factor is calculated using the following formula:

[0087]

[0088] In the formula, IF coal (d) represents the dynamic influencing factor; α represents the coal rank coefficient; T h Represents the coal seam thickness; ROP(d) represents the drilling time value at any depth point; A represents the attenuation factor.

[0089] Example 6: As an optimization of the above examples, the stripping coefficient in the gas measurement data correction formula is obtained by the following method:

[0090] Using the mudstone section without coal seam interference as the background section, the original gas measurement value of the background section as the y-value, and the dynamic influence factor as the x-value, data fitting is performed, and the coefficient of the x-term in the fitting formula is used as the stripping coefficient.

[0091] Example 7: As an optimization of the above examples, the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam is obtained according to the following formula:

[0092]

[0093] In the formula, δd represents the distance between any depth point and the nearest boundary of the coal seam; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; d represents any depth point.

[0094] Example 8: As an optimization of the above example, for sandstone, if the following four conditions are met simultaneously, the reservoir corresponding to any depth point d is determined to be a gas layer; otherwise, it is determined to be a non-gas layer.

[0095] Gas logging data: TG 校正 (d)≥2×TG bg The measured humidity ratio Wh(d) is ≤40%;

[0096] In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point d; TG bg Represents background atmospheric value;

[0097] Well logging data: ;

[0098] In the formula, RT sand (d) represents the corrected resistivity at any depth point d; AC represents the acoustic transit time.

[0099] Example 9: An apparatus for eliminating coal seam interference in accurate gas well reservoir identification as described in the above examples, comprising:

[0100] Coal seam identification and parameter extraction module: The existence of coal seams is confirmed by using the gamma curve, resistivity curve and cuttings ratio in cuttings logging. If a coal seam exists, the top and bottom depths of the coal seam are extracted, and the center depth and thickness of the coal seam are calculated based on the top and bottom depths.

[0101] The module for calculating dynamic impact factors calculates the coal rank coefficient based on the coal rank parameters of the coal seam sample, extracts the drilling time value at any depth point, calculates the attenuation factor according to the exponential decay law using the vertical distance between the arbitrary depth point and the center of the coal seam, and calculates the dynamic impact factor based on the coal seam thickness, coal rank coefficient, drilling time value at any depth point, and attenuation factor.

[0102] Gas logging data correction module: Based on the gas logging data correction formula, it obtains the gas logging correction value at any depth point. The gas logging data correction formula is as follows:

[0103]

[0104] In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point; TG raw (d) represents the original gas measurement value at any depth point; γ represents the stripping coefficient; IF coal (d) represents the dynamic influencing factor; d represents any depth point.

[0105] Resistivity correction module: The corrected resistivity is obtained based on the resistivity correction formula, as shown below:

[0106]

[0107] In the formula, RT sand (d) represents the corrected resistivity at any depth point; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; RT log (d) represents the resistivity measurement at any depth point; RT coal d represents the median resistivity of the coal seam, and d represents any depth point;

[0108] From the resistivity measurement RT log (d) Subtract the coal seam (resistivity RT) coal The volume contribution (V) of ) coal(d) Calculate the remaining part (1-V) coal (d) represents the true resistivity RT of the sandstone portion. sand (d)

[0109] Reservoir type identification module: Combines gas logging correction values, corrected resistivity, gas logging humidity ratio, and acoustic transit time to identify reservoir type.

[0110] The core idea of ​​this invention is "quantitative stripping" and "reverse correction." It doesn't simply remove coal seam data, but rather precisely quantifies the contribution of the coal seam to the measurement values ​​at each arbitrary depth point (including original gas measurements and resistivity measurements), and then subtracts this contribution from the measurement values ​​to obtain the "true" value that only represents the properties of the reservoir (such as sandstone) itself. Specifically:

[0111] 1) Eliminating the influence of coal seams on gas logging data

[0112] The core of this method is the introduction of the dynamic impact factor IF. coal (d) This dynamic influence factor cleverly models the influence of coal seams as a physical process that decays exponentially with distance from the center of the coal seam.

[0113] α (coal rank coefficient): measures the gas production capacity of different coal ranks (from lignite to anthracite). Higher-rank coals have higher gas content and larger coal rank parameters (Ro), contributing more to gas measurement; therefore, a coefficient is needed to amplify this difference. α is the regulator that amplifies this difference. .

[0114] Coal seam thickness Th: The thicker the coal seam, the more gas it can theoretically release, and the greater its impact.

[0115] ROP (Recovery Point Operation) during drilling: This is a key dynamic parameter. A fast drilling rate (low ROP value) results in less coal breakage per unit time, potentially leading to a low instantaneous gas indication; conversely, a slow drilling rate (high ROP value) results in more coal breakage per unit time, leading to an abnormally high instantaneous gas indication. Introducing ROP can significantly reduce the interference of drilling engineering parameters on gas logging data, making the corrected gas logging values ​​closer to geological realities.

[0116] Attenuation factor A: quantifies the degree to which the effect decreases with distance. The farther away from the center of the coal seam (the larger |d-Dc| is), the smaller the attenuation factor and the smaller the effect.

[0117] β is the decay constant, which controls the decay rate.

[0118] For the gas measurement data correction formula: ,

[0119] The physical meaning of the atmospheric measurement data correction formula: at any depth point d, the original atmospheric measurement value ( It consists of two parts: background atmospheric value (TG) bg ) + Gas contribution from coal seam (γ*IF) coal (d)). After obtaining the stripping coefficient γ through regression fitting, the gas produced by the coal seam can be subtracted from the original gas measurement value to obtain the final gas measurement correction value TG. 校正 (d) is the hydrocarbon gas value that excludes coal seam interference and truly originates from reservoir pores.

[0120] 2) The impact of coal seam removal on well logging resistivity

[0121] The core of this method is inversion based on a volumetric physical model. It treats the resistivity measurements of the logging instrument as a parallel result of the resistances of the coal seam and the reservoir.

[0122] Volume inversion correction: Calculate the percentage of the volume occupied by the coal seam within the detection range of the logging instrument. Segmented formula design: Very close to the coal seam boundary (δd≤0.5m): The majority of the detection range of the logging instrument is coal, and a linear relationship is used (i.e.,... Rapid calculation. Far from the coal seam boundary (δd>0.5m): the influence of the coal seam decreases, and an exponential decay model is adopted (i.e., ).

[0123] Physical meaning of resistivity correction formula: resistivity measurement value RT log (d) Given, subtract the median resistivity RT of the coal seam from it. coal Volume contribution (V) coal (d) Calculate the remaining part (1-V) coal (d) thus obtaining the true resistivity of the reservoir, i.e., the corrected resistivity RT. sand (d)

[0124] Example 10: The method for coal seam elimination in accurate gas well reservoir identification described in this invention was applied to well Su77-XX-XX. Well Su77-XX-XX: coal seam center depth 2051m, coal seam thickness 2m, coal rank parameter Ro=4.63, target layer depth (i.e., arbitrary depth d) 2055m, background gas value TG. bg =1%; original gas measurement value 5%, resistivity measurement value is 1%; The median resistivity of the coal seam is .

[0125] 1) Calculate the coal rank coefficient

[0126]

[0127] 2) Gas measurement data correction (γ≈0.8):

[0128] Stripping coefficient γ: Using the mudstone section without coal seam interference as the background section, the original gas measurement value of the background section as the y-value, and the dynamic influence factor as the x-value, data fitting is performed (see...). Figure 1 When the mathematical model is linear, the fit R is... 2 The coefficient is as high as 0.9781. Therefore, the coefficient of the x term in the linear fitting formula y=0.8243x+0.3443 is 0.8243 (≈0.8), which is the stripping coefficient γ.

[0129]

[0130] 3) Resistivity correction (δd=3m):

[0131]

[0132] 4) Reservoir type identification

[0133] Gas logging data: ;

[0134] Well logging data: ;

[0135] Based on comprehensive assessment, it is determined to be a non-gas layer.

[0136] When the method described in this invention was applied to a gas field, 33 target layers were identified, and 19 were determined to be gas layers. After fracturing and gas testing, 18 of them were verified to be gas layers, with an effectiveness rate of 94.7%, indicating that the method described in this invention can effectively identify gas layers.

[0137] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for accurately identifying gas well reservoirs and eliminating coal seam interference, characterized in that, include: The existence of coal seams is confirmed by using the gamma ray curve, resistivity curve and cuttings ratio in cuttings logging. If coal seams exist, the top and bottom depths of the coal seams are extracted, and the center depth and thickness of the coal seams are calculated based on the top and bottom depths. The coal rank coefficient is calculated based on the coal rank parameters of the coal seam sample. The drilling time value at any depth point is extracted. The attenuation factor is calculated according to the exponential attenuation law using the vertical distance between the arbitrary depth point and the center of the coal seam. The dynamic influence factor is calculated based on the coal seam thickness, coal rank coefficient, drilling time value at any depth point and attenuation factor. Based on the gas measurement data correction formula, the gas measurement correction value at any depth point is obtained. The gas measurement data correction formula is as follows: TG 校正 (d)=TG raw (d)-γ*IF coal (d) / 100 (1) In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point; TG raw (d) represents the original gas measurement value at any depth point; γ represents the stripping coefficient; IF coal (d) represents the dynamic influencing factor; d represents any depth point. The corrected resistivity is obtained based on the resistivity correction formula, and the corrected resistivity is as follows: In the formula, RT sand (d) represents the corrected resistivity at any depth point; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; RT log (d) represents the resistivity measurement at any depth point; RT coal d represents the median resistivity of the coal seam, and d represents any depth point; The reservoir type is determined by combining the gas measurement correction value, correction resistivity, gas measurement humidity ratio, and acoustic transit time. The coal rank coefficient is calculated using the following formula: α=0.2*log 10 (Ro+1) (3) In the formula, α represents the coal rank coefficient; Ro represents the coal rank parameter; The attenuation factor is calculated using the following formula: In the formula, A represents the attenuation factor; β is the attenuation constant; d-Dc represents the vertical distance between an arbitrary depth point and the center of the coal seam; d represents an arbitrary depth point; Dc represents the depth of the coal seam center. The dynamic impact factor is calculated using the following formula: IF coal (d)=α*T h *ROP(d)*A (5) In the formula, IF coal (d) represents the dynamic influencing factor; α represents the coal rank coefficient; T h Represents the coal seam thickness; ROP(d) represents the drilling time value at any depth point; A represents the attenuation factor.

2. The method for eliminating coal seam interference in accurate gas well reservoir identification according to claim 1, characterized in that, The existence of coal seams was confirmed using drilling gamma-ray curves, resistivity curves, and the proportion of coal cuttings in cuttings logging. Specifically, this included: A coal seam exists when the following conditions are simultaneously met by the drilling gamma ray curve, resistivity curve, and cuttings logging coal cuttings ratio: The GR value in the gamma-ray disc of the continuous section is greater than 150 API; the resistivity value of the resistivity curve of the continuous section is <10 Ω·m; and the proportion of cuttings in the cuttings logging of the continuous section is ≥70%.

3. The method for eliminating coal seam interference in accurate gas well reservoir identification according to claim 1 or 2, characterized in that, The stripping coefficient in the gas measurement data correction formula is obtained as follows: Using the mudstone section without coal seam interference as the background section, the original gas measurement value of the background section as the y-value, and the dynamic influence factor as the x-value, data fitting is performed, and the x-coefficient in the fitting formula is used as the stripping coefficient. Or / and, the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam is obtained by the following formula: If δd≤0.5m, If δd > 0.5m, In the formula, δd represents the distance between any depth point and the nearest boundary of the coal seam; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; d represents any depth point.

4. The method for eliminating coal seam interference in accurate gas well reservoir identification according to claim 1 or 2, characterized in that, For sandstone, if the following four conditions are met simultaneously, the reservoir corresponding to any depth point d is determined to be a gas reservoir; otherwise, it is determined to be a non-gas reservoir. Gas logging data: TG 校正 (d)≥2×TG bg The measured humidity ratio Wh(d) is ≤40%; In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point d; TG bg Represents background atmospheric value; Well logging data: , ; In the formula, RT sand (d) represents the corrected resistivity at any depth point d; AC(d) represents the acoustic transit time at any depth point d.

5. The method for accurately identifying gas well reservoirs and eliminating coal seam interference according to claim 3, characterized in that, For sandstone, if the following four conditions are met simultaneously, the reservoir corresponding to any depth point d is determined to be a gas reservoir; otherwise, it is determined to be a non-gas reservoir. Gas logging data: TG 校正 (d)≥2*TG bg The measured humidity ratio Wh(d) is ≤40%; In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point d; TG bg Represents background atmospheric value; Well logging data: , ; In the formula, RT sand (d) represents the corrected resistivity at any depth point d; AC(d) represents the acoustic transit time at any depth point d.

6. An apparatus for eliminating coal seam interference in accurate gas well reservoir identification as described in any one of claims 1 to 5, characterized in that, include: Coal seam identification and parameter extraction module: The existence of coal seams is confirmed by using the gamma curve, resistivity curve and cuttings ratio in cuttings logging. If a coal seam exists, the top and bottom depths of the coal seam are extracted, and the center depth and thickness of the coal seam are calculated based on the top and bottom depths. The module for calculating dynamic impact factors calculates the coal rank coefficient based on the coal rank parameters of the coal seam sample, extracts the drilling time value at any depth point, calculates the attenuation factor according to the exponential decay law using the vertical distance between the arbitrary depth point and the center of the coal seam, and calculates the dynamic impact factor based on the coal seam thickness, coal rank coefficient, drilling time value at any depth point, and attenuation factor. Gas measurement data correction module: Based on the gas measurement data correction formula, it obtains the gas measurement correction value at any depth point. The gas measurement data correction formula is as follows: TG 校正 (d)=TG raw (d)-γ*IF coal (d) / 100 (1) In the formula, TG 校正 (d) represents the atmospheric measurement correction value at any depth point; TG raw (d) represents the original gas measurement value at any depth point; γ represents the stripping coefficient; IF coal (d) represents the dynamic influencing factor; d represents any depth point. Resistivity correction module: The corrected resistivity is obtained based on the resistivity correction formula, as shown below: In the formula, RT sand (d) represents the corrected resistivity at any depth point; V coal (d) represents the proportion of coal seam volume corresponding to the distance between any depth point and the nearest boundary of the coal seam; RT log (d) represents the resistivity measurement at any depth point; RT coal d represents the median resistivity of the coal seam, and d represents any depth point; Reservoir type identification module: Combines gas logging correction values, corrected resistivity, gas logging humidity ratio, and acoustic transit time to identify reservoir type.

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