Gas logging total hydrocarbon anomaly multiple calculation method

Abstract

The invention discloses a gas logging total hydrocarbon anomaly multiple calculation method, and relates to the technical field of natural gas exploration, and the method comprises the following steps: S1, collecting gas logging data and rock debris logging data of a single well, and dividing the single well into a preliminary reservoir section and a preliminary non-reservoir section; s2, determining a preliminary reservoir section thickness and a preliminary non-reservoir section thickness; s3, according to the preliminary reservoir section thickness and the preliminary non-reservoir section thickness, the reservoir section and the non-reservoir section are divided again; s4, calculating a background base value of a non-reservoir section; and S5, calculating the abnormal multiple of the reservoir section according to the background base values of the reservoir section and the non-reservoir section. According to the method, the local stationary subinterval in the non-reservoir section is extracted by adopting the sliding window method, and the background base value is calculated based on weighted average, so that the interference of an abnormal value and trend fluctuation on the background base value is effectively inhibited, the accuracy and stability of gas logging total hydrocarbon anomaly multiple calculation are remarkably improved, and the method has important application value and popularization prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas exploration, and particularly relates to a gas logging total hydrocarbon abnormal multiple calculation method. BACKGROUND

[0002] In the process of oil exploration, accurately identifying the fluid properties in the reservoir is one of the key links to determine the reservoir type (such as oil-bearing layer and gas-bearing layer). This information is of great significance for discovering oil and gas fields and evaluating the economic value of oil and gas reservoirs. Through in-depth analysis of the fluid properties, geologists and petroleum engineers can more scientifically predict the productivity and production performance of the reservoir, thereby optimizing the development plan. Therefore, accurately mastering the properties of the fluid in the reservoir is the basis for improving the effect of oil and gas exploration and development, and directly affects the success rate of oilfield exploration and economic benefits.

[0003] In the process of drilling operation, the fluid in the formation will enter the wellbore in various forms and return to the ground together with the drilling fluid. In the ground environment, these fluids may appear in gaseous or liquid state. Formation gas mainly includes hydrocarbon gas, non-hydrocarbon gas and harmful gas such as hydrogen sulfide (H2S) which is dangerous. Through real-time monitoring and analysis of these hydrocarbon and non-hydrocarbon gases, the existence and properties of oil and gas layers and water layers can be quickly identified and evaluated, thereby providing an important reference for drilling operation and ensuring the safety of operation and improving the exploration efficiency.

[0004] Gas logging is a logging method that uses a gas detection system to detect and analyze the content of hydrocarbon gas separated from the drilling fluid by a degasser. The main purpose is to timely discover oil and gas shows, predict well kick, blowout and gas invasion, and comprehensively evaluate the reservoir. Total hydrocarbon (Tg) refers to the total content of hydrocarbon (including C1, C2, C3, iC4, nC4, iC5 and nC5) in the sample gas input into the gas chromatograph, which is directly analyzed and output by a hydrogen flame ionization detector. The total hydrocarbon content usually indicates the quality of oil and gas shows and is a commonly used index in the field of gas logging. However, relying solely on the absolute value of total hydrocarbon may ignore the background value of the overlying non-reservoir section (usually a mudstone section). Gas logging abnormal multiple refers to the ratio of the abnormal value of gas logging total hydrocarbon content in a well section to its background value. The background value, also known as the base value, usually refers to the lowest total hydrocarbon content or the average total hydrocarbon content in the original curve above the gas logging anomaly. The larger the abnormal multiple, the more significant the anomaly, and the higher the possibility of oil and gas in the reservoir. At present, the calculation of gas logging abnormal multiple usually adopts a manual method to select the lowest total hydrocarbon content or the average total hydrocarbon content of the overlying non-reservoir section as the calculation base value. The manual method has the problems of subjectivity and low efficiency. Therefore, it is urgent to propose a gas logging total hydrocarbon abnormal multiple calculation method to efficiently and accurately calculate the gas logging total hydrocarbon abnormal multiple. SUMMARY

[0005] The application provides a gas logging total hydrocarbon abnormal multiple calculation method.

[0006] The technical scheme of the application is as follows:

[0007] S1, collecting gas logging data and rock logging data of a single well, and dividing a preliminary reservoir section and a preliminary non-reservoir section;

[0008] S2, determining the thickness of the preliminary reservoir section and the thickness of the preliminary non-reservoir section;

[0009] S3, re-dividing a reservoir section and a non-reservoir section according to the thickness of the preliminary reservoir section and the thickness of the preliminary non-reservoir section;

[0010] S4, calculating a background base value of the non-reservoir section;

[0011] S5, calculating an abnormal multiple of the reservoir section according to the background base value of the reservoir section and the background base value of the non-reservoir section.

[0012] Further, in S1, if the lithology is sandstone, the sandstone is divided into the reservoir section; if the lithology is mudstone, the mudstone is divided into the non-reservoir section.

[0013] Further, S3 includes the following sub-steps:

[0014] S31, constructing a lithology sequence and a thickness sequence according to the thickness of the preliminary reservoir section and the thickness of the preliminary non-reservoir section;

[0015] S32, setting a first pointer starting point p of an expected lithology as a pointer initial position when the expected lithology is mudstone;

[0016] S33, based on the lithology sequence, starting from the pointer initial position, searching for a re-divided mudstone non-reservoir section;

[0017] S34, based on the mudstone non-reservoir section and the thickness sequence of the secondary division, starting from the pointer initial position, searching for a re-divided sandstone reservoir section.

[0018] Further, in S31, the lithology sequence is expressed as:

[0019] ;

[0020] In the formula, the first lithology is represented by , the second lithology is represented by , the n th lithology sequence is represented by , the N th lithology sequence is represented by , S represents that the lithology is sandstone, and M represents that the lithology is mudstone;

[0021] In S31, the thickness sequence The expression of the formula is:

[0022] ;

[0023] In the formula, T1 represents the first segment thickness, T2 represents the second segment thickness, T n represents the nth segment thickness, and T N represents the Nth segment thickness.

[0024] In S32, the value range of p at the initial position of the pointer is represented as:

[0025] ;

[0026] The initial position of the pointer is used to mark the current expected lithology type expect, and the expression is:

[0027] ;

[0028] In S33, from the initial position of the pointer, the maximum interval satisfying the continuous mudstone segment is found , and the mudstone non-reservoir segment after re-division is obtained, and the expression is:

[0029] ;

[0030] In the formula, represents the nth segment lithology, p represents the starting point of the current pointer, and q represents the end point of the current pointer.

[0031] Further, S34 includes the following sub-steps:

[0032] S341, determining a sandstone subset and a mudstone subset from the initial position of the pointer;

[0033] S342, calculating the total thickness of the sandstone subset and the total thickness of the mudstone subset;

[0034] S343, calculating the maximum thickness of the single-layer mudstone subset;

[0035] S344, calculating the intercalated mudstone thickness ratio according to the total thickness of the sandstone subset and the total thickness of the mudstone subset;

[0036] S345, calculating the symmetry index;

[0037] S346, determining the division condition according to the maximum thickness of the single-layer mudstone subset, the intercalated mudstone thickness ratio, and the symmetry index;

[0038] S347, expanding the end point of the maximum interval of the large set of sandstone reservoirs from the initial position of the pointer until the division condition is met, to obtain the current maximum interval;

[0039] S348, divide the current maximum satisfaction interval into sandstone reservoir interval, and update the current pointer, and iteratively find the reservoir section and non-reservoir section.

[0040] Further, in S341, the expression of the sandstone subset is:

[0041] ;

[0042] In the formula, p represents the starting point of the current pointer, q represents the ending point of the current pointer, n represents the nth lithology sequence, and S represents the lithology of the sandstone type;

[0043] In S341, the expression of the shale subset is:

[0044] ;

[0045] In the formula, M represents the lithology of the shale type;

[0046] In S342, the expression of the total thickness of the sandstone subset is:

[0047] ;

[0048] In the formula, T n n represents the nth thickness;

[0049] In S342, the expression of the total thickness of the shale subset is:

[0050] ;

[0051] In S343, the expression of the maximum thickness of the single-layer shale subset is:

[0052] ;

[0053] In S344, the expression of the thickness proportion of the intercalated shale is:

[0054] ;

[0055] In S345, the expression of the symmetry index R p,q is:

[0056] ;

[0057] In the formula, Median(·) represents the median operation, and max(·) represents the maximum operation;

[0058] In S346, the expression of the division condition is:

[0059] ;

[0060] In the formula, denotes the sequence start point, denotes the sequence end point, T S,min denotes the minimum total thickness of the merged sandstone reservoir interval, T M,max denotes the maximum allowable thickness of a single layer of mudstone, R min denotes the lower limit of the sandstone thickness symmetry index, and a denotes the maximum allowable value of the proportion of intercalated mudstone thickness.

[0061] Further, S4 includes the following sub-steps:

[0062] S41, constructing a Tg value sequence of a non-reservoir section;

[0063] S42, processing the Tg value sequence of the non-reservoir section through a sliding window to obtain a mean value;

[0064] S43, calculating a fluctuation amplitude according to the mean value;

[0065] S44, determining a set of window indices that satisfy the stationary condition according to the fluctuation amplitude;

[0066] S45, calculating a background base value of the non-reservoir section according to the set of window indices that satisfy the stationary condition.

[0067] Further, in S41, the expression of the Tg value sequence of the non-reservoir section is:

[0068] ;

[0069] In the formula, d1 denotes the depth value of the first depth point, d2 denotes the depth value of the second depth point, d i denotes the depth value of the i-th depth point, d P denotes the depth value of the P-th depth point, Tg1 denotes the Tg value corresponding to the first depth point, Tg2 denotes the Tg value corresponding to the second depth point, Tg i denotes the Tg value corresponding to the i-th depth point, Tg P denotes the Tg value corresponding to the P-th depth point;

[0070] In S42, the expression of the mean value is:

[0071] ;

[0072] In the formula, w denotes the fixed window length, Tg i+k denotes the j-th Tg value as the starting point, and the k-th Tg value behind.

[0073] In S43, the fluctuation amplitude σ j The expression is:

[0074] ;

[0075] In S44, the expression of the set of all window indexes satisfying the stationary condition is:

[0076] ;

[0077] In the formula, τ represents the determination threshold of fluctuation, and j represents the starting index of the window;

[0078] In S45, the expression of the background base value B of the non-reservoir section is:

[0079] ;

[0080] In the formula, ε represents a small constant to prevent division by zero.

[0081] Further, in S5, the abnormal multiple of the reservoir section is calculated according to the ratio between the Tg value of each depth point of the reservoir section and the background base value of the non-reservoir section.

[0082] The beneficial effects of the present application are: the present application comprehensively applies gas logging data and cutting logging data, and innovatively realizes automatic intelligent division of reservoirs and overlying non-reservoirs, overcoming the defects of strong subjectivity and low efficiency of traditional manual division. The sliding window method is used to extract local stationary subintervals in the non-reservoir section, and the background base value is calculated based on weighted average, effectively suppressing the interference of abnormal values and trend fluctuations on the background base value, significantly improving the accuracy and stability of gas logging total hydrocarbon abnormal multiple calculation, and having important application value and popularization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0083] Figure 1 It is a flowchart of the gas logging total hydrocarbon abnormal multiple calculation method. DETAILED DESCRIPTION

[0084] The embodiments of the present application will be further described below with reference to the accompanying drawings.

[0085] As Figure 1 shown, the present application provides a gas logging total hydrocarbon abnormal multiple calculation method, comprising the following steps:

[0086] S1, collecting gas logging data and cutting logging data of a single well, and dividing preliminary reservoir sections and preliminary non-reservoir sections;

[0087] S2, determining the thickness of the preliminary reservoir section and the thickness of the preliminary non-reservoir section;

[0088] ​S3, according to the preliminary reservoir section thickness and the preliminary non-reservoir section thickness, re-divide the reservoir section and the non-reservoir section again;

[0089] S4, calculate the background base value of the non-reservoir section;

[0090] S5, according to the background base value of the reservoir section and the non-reservoir section, calculate the abnormal multiple of the reservoir section.

[0091] In the embodiment of the present application, in S1, if the lithology is sandstone, it is divided into a reservoir section; if the lithology is mudstone, it is divided into a non-reservoir section.

[0092] The data is mainly stored in the form of tables output by the field logging instrument and manual cutting description. Among them, the gas logging data resolution is 1 meter 1 data row, and the data column includes a continuous depth column and a gas logging total hydrocarbon column; the cutting logging data column includes top depth, bottom depth, thickness and lithology column. According to the depth of the gas logging data, the cutting logging data is matched according to its top depth and bottom depth to form a data form with a continuous depth column, a gas logging total hydrocarbon column and a lithology column.

[0093] In the embodiment of the present application, according to each preliminary reservoir thickness, the non-reservoir section and the reservoir section are re-divided. The purpose of re-dividing is to remove the non-reservoir section of the thin layer and the interbedded mudstone in the large set of sandstone reservoir. These non-reservoir sections are too close to the reservoir section, so they are not suitable as the background base value of the lower reservoir section, and a special classification method is needed to reclassify the reservoir section and the non-reservoir section. In order to construct a reasonable reservoir model, it is necessary to automatically divide the interval that meets the geological and reservoir physical properties according to the lithology and thickness information, and the output interval must maintain the alternating arrangement order of the non-reservoir section and the sandstone reservoir section, and the first section of the sequence is the mudstone non-reservoir section, which ensures the logical continuity and isolation of the reservoir and the non-reservoir. The present application automatically judges and merges the interval based on the sliding window and the physical threshold, taking into account the mudstone thickness limit and the sandstone thickness uniformity index, and realizes intelligent division. S3 includes the following sub-steps:

[0094] S31, according to the preliminary reservoir section thickness and the preliminary non-reservoir section thickness, construct a lithology sequence and a thickness sequence;

[0095] S32, set the starting point p of the first pointer to the desired lithology as the initial position of the pointer;

[0096] S33, based on the lithology sequence, start from the initial position of the pointer to find the re-divided mudstone non-reservoir section;

[0097] S34, based on the mudstone non-reservoir interval of the secondary division and the thickness sequence, start from the initial position of the pointer to find the re-divided sandstone reservoir section.

[0098] In the embodiment of the present application, in S31, the lithology sequence The expression of the lithology sequence is:

[0099] ;

[0100] In the formula, represents the lithology of the first section, represents the lithology of the second section, represents the lithology sequence of the nth section, represents the lithology sequence of the Nth section, S represents that the lithology is sandstone, and M represents that the lithology is mudstone;

[0101] In S31, the thickness sequence is expressed as:

[0102] ;

[0103] In the formula, T1 represents the thickness of the first section, T2 represents the thickness of the second section, T n represents the thickness of the nth section, and T N represents the thickness of the Nth section;

[0104] In S32, at the beginning, the value range of p at the initial position of the pointer is expressed as:

[0105] ;

[0106] The initial position of the pointer is used to mark the current expected lithology type expect, and the expression is:

[0107] ;

[0108] In S33, from the initial position of the pointer, the maximum interval satisfying the continuous mudstone section is found, and the mudstone non-reservoir section after re-division is obtained, and the expression is:

[0109] ;

[0110] In the formula, represents the lithology of the nth section, p represents the starting point of the current pointer, and q represents the end point of the current pointer.

[0111] In the embodiment of the present application, S34 includes the following sub-steps:

[0112] S341, starting from the initial position of the pointer, determining a sandstone subset and a mudstone subset;

[0113] S342, calculating the total thickness of the sandstone subset and the total thickness of the mudstone subset;

[0114] S343, calculating the maximum thickness of the single-layer mudstone subset;

[0115] S344, according to the total thickness of the sandstone subset and the total thickness of the shale subset, calculate the shale thickness proportion;

[0116] S345, calculate the symmetry index;

[0117] S346, according to the maximum thickness of the single-layer shale subset, the shale thickness proportion and the symmetry index, determine the division condition;

[0118] S347, expand the end point of the maximum interval of the large set of sandstone reservoirs from the initial position of the pointer until the division condition is met, to obtain the current maximum meeting interval;

[0119] S348, divide the current maximum meeting interval into a sandstone reservoir interval, and update the current pointer to iteratively find the reservoir section and the non-reservoir section.

[0120] In the embodiment of the application, in S341, the expression of the sandstone subset is:

[0121] ;

[0122] In the formula, p represents the starting point of the current pointer, q represents the end point of the current pointer, n represents the nth lithology sequence, and S represents the lithology of the sandstone subset;

[0123] In S341, the expression of the shale subset is:

[0124] ;

[0125] In the formula, M represents the lithology of the shale subset;

[0126] In S342, the expression of the total thickness of the sandstone subset is:

[0127] ;

[0128] In the formula, T n n represents the nth thickness;

[0129] In S342, the expression of the total thickness of the shale subset is:

[0130] ;

[0131] In S343, the expression of the maximum thickness of the single-layer shale subset is:

[0132] ;

[0133] ​​​​​In S344, the expression of the proportion of the thickness of the interbedded mudstone is The expression is

[0134] ;

[0135] In S345, the expression of the symmetry index R p,q of the sandstone is

[0136] ;

[0137] In the expression, Median(·) represents the median operation, and max(·) represents the maximum value operation;

[0138] In S346, the expression of the division condition is

[0139] ;

[0140] In the expression, represents the start of the sequence, represents the end of the sequence, T S,min represents the minimum total thickness of the merged sandstone reservoir interval, T M,max represents the maximum allowed thickness of a single layer of mudstone, R min represents the lower limit of the sandstone thickness symmetry index, and α represents the maximum allowed value of the proportion of the thickness of the interbedded mudstone.

[0141] If the division condition is not met, the expansion is stopped, and the current maximum satisfied interval [p, q-1] is divided into a sandstone reservoir interval. After dividing the reservoir interval, the value of the pointer p is updated to be equal to q, the expected interval type is switched to a mudstone non-reservoir section, and then the mudstone non-reservoir interval is repeatedly searched, and the sandstone reservoir interval is repeatedly searched. Repeat this process. Finally, the non-reservoir section and the reservoir section are divided twice.

[0142] In the embodiments of the present application, the Tg of the non-reservoir section often has certain fluctuations or trends within the entire interval. Directly using the mean or median of the entire interval as the background base value may cause distortion of the background value due to local outliers or trends. By searching for one or more sub-intervals with smaller fluctuations and stability in the mudstone interval, these sub-intervals can better represent the stable background characteristics of the mudstone interval, avoiding interference due to outliers or trends. Weighted average the characteristic values (such as the mean) of these stable sub-intervals to obtain a more accurate and robust background base value. S4 includes the following sub-steps:

[0143] S41, constructing a sequence of Tg values of the non-reservoir section;

[0144] S42, processing the sequence of Tg values of the non-reservoir section by a sliding window to obtain a mean value;

[0145] S43, calculating the fluctuation amplitude according to the mean value;

[0146] S44, determining a set of window indexes satisfying the stationary condition according to the fluctuation amplitude;

[0147] S45, calculating the non-reservoir section background base value according to the set of window indexes satisfying the stationary condition.

[0148] In the embodiment of the present application, in S41, the expression of the Tg value sequence of the non-reservoir section is:

[0149] ;

[0150] In the expression, d1 represents the depth value of the first depth point, d2 represents the depth value of the second depth point, d i represents the depth value of the i-th depth point, d P represents the depth value of the P-th depth point, Tg1 represents the Tg value corresponding to the first depth point, Tg2 represents the Tg value corresponding to the second depth point, Tgi represents the Tg value corresponding to the i-th depth point, and Tg i represents the Tg value corresponding to the P-th depth point. P

[0151] In S42, the expression of the mean value is:

[0152] ;

[0153] In the expression, w represents the fixed window length, Tg i+k represents the Tg value k steps behind the Tg value starting from the j-th Tg value.

[0154] In S43, the expression of the fluctuation amplitude σ j is:

[0155] ;

[0156] In S44, the expression of the set of window indexes satisfying the stationary condition is:

[0157] ;

[0158] In the expression, τ represents the determination threshold of the fluctuation, and j represents the starting index of the window.

[0159] In S45, the expression of the non-reservoir section background base value B is:

[0160] ;

[0161] In the expression, ε represents a small constant for preventing division by zero.

[0162] ​In the embodiment of the present application, in S5, the abnormal multiple of the reservoir section is calculated according to the ratio between the Tg value of each depth point of the reservoir section and the background base value of the non-reservoir section.

[0163] Those skilled in the art will understand that the embodiments described herein are for the purpose of helping the reader understand the principles of the present application, and should be understood as not limiting the scope of protection of the present application to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations according to the technical inspiration disclosed in the present application without departing from the essence of the present application, and these modifications and combinations are still within the scope of protection of the present application.

Claims

1. A method for calculating the anomaly multiple of total hydrocarbons in gas chromatography, characterized in that, Includes the following steps: S1. Collect gas logging data and cuttings logging data from a single well, and divide the preliminary reservoir section and the preliminary non-reservoir section. S2. Determine the initial thickness of the reservoir section and the initial thickness of the non-reservoir section; S3. Based on the initial reservoir section thickness and the initial non-reservoir section thickness, the reservoir section and non-reservoir section are further divided; S4. Calculate the background baseline value of the non-reservoir section; S5. Calculate the anomaly multiple of the reservoir section based on the background baseline values ​​of the reservoir section and the non-reservoir section.

2. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 1, characterized in that, In S1, if the lithology is sandstone, it is classified as a preliminary reservoir section; if the lithology is mudstone, it is classified as a preliminary non-reservoir section.

3. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 1, characterized in that, S3 includes the following sub-steps: S31. Construct lithological and thickness sequences based on the preliminary reservoir section thickness and the preliminary non-reservoir section thickness; S32. Set the first pointer starting point p when the desired lithology is mudstone as the pointer initial position; S33. Based on the lithological sequence, starting from the initial position of the pointer, find the mudstone non-reservoir section to be subdivided again; S34. Based on the secondary division of mudstone non-reservoir intervals and thickness sequences, starting from the initial position of the pointer, search for the sandstone reservoir intervals that are further divided.

4. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 3, characterized in that, In S31, the lithological sequence The expression is: ； In the formula, Indicates the lithology of the first section. Indicates the lithology of the second section. This represents the nth segment of the lithological sequence. This represents the Nth segment of the lithological sequence, where S indicates that the lithology is sandstone and M indicates that the lithology is mudstone. In S31, the thickness sequence The expression is: ； In the formula, T1 represents the thickness of the first segment, T2 represents the thickness of the second segment, and T... n T represents the thickness of the nth segment. N Indicates the thickness of the Nth segment; In step S32, the initial value range of pointer p is expressed as follows: ； The initial position of the pointer is used to mark the current expected lithology type, expect, and its expression is: ； In step S33, starting from the initial position of the pointer, the maximum interval that satisfies the continuous mudstone segment is searched. The resulting subdivided mudstone non-reservoir section is expressed as follows: ； In the formula, Let p represent the lithology of the nth segment, p represent the starting point of the current pointer, and q represent the ending point of the current pointer.

5. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 3, characterized in that, S34 includes the following sub-steps: S341. Starting from the initial position of the pointer, determine the sandstone subset and the mudstone subset; S342. Calculate the total thickness of the sandstone subset and the total thickness of the mudstone subset; S343. Calculate the maximum thickness of a single mudstone subset; S344. Calculate the thickness ratio of interbedded mudstone based on the total thickness of the sandstone subset and the total thickness of the mudstone subset. S345. Calculate the symmetry index; S346. Determine the classification conditions based on the maximum thickness of the single-layer mudstone subset, the proportion of mudstone thickness, and the symmetry index; S347. Starting from the initial position of the pointer, expand the endpoint of the maximum interval of the large sandstone reservoir until the division conditions are met, and obtain the current maximum satisfied interval; S348. Divide the current maximum satisfied interval into sandstone reservoir intervals, update the current pointer, and iteratively search for reservoir segments and non-reservoir segments.

6. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 5, characterized in that, In S341, the sandstone subset The expression is: ； In the formula, p represents the current starting point of the pointer, and q represents the current ending point of the pointer. This represents the nth segment of the lithological sequence, where S indicates that the lithology is sandstone. In S341, the mudstone subset The expression is: ； In the formula, M represents mudstone; In S342, the total thickness of the sandstone subset The expression is: ； In the formula, T n Indicates the thickness of the nth segment; In S342, the total thickness of the mudstone subset The expression is: ； In S343, the maximum thickness of the single-layer mudstone subset The expression is: ； In S344, the thickness ratio of the mudstone inclusions The expression is: ； In S345, the symmetry index R p,q The expression is: ； In the formula, Median(·) represents the median operation, and max(·) represents the maximum value operation; In S346, the expression for the partitioning condition is: ； In the formula, Indicates the start of the sequence. T represents the end point of the sequence. S,min T represents the minimum total thickness of the merged sandstone reservoir section. M,max R represents the maximum allowable thickness of a single layer of mudstone. min α represents the lower limit of the sandstone thickness symmetry index, and α represents the maximum allowable value of the proportion of mudstone inclusions.

7. The method for calculating the anomaly multiple of total hydrocarbons in gas analysis according to claim 1, characterized in that, S4 includes the following sub-steps: S41. Construct a Tg value sequence for non-reservoir sections; S42. The Tg value sequence of non-reservoir sections is processed by a sliding window to obtain the mean value; S43. Calculate the fluctuation range based on the mean; S44. Based on the fluctuation amplitude, determine the set of all window indices that meet the stationarity condition; S45. Calculate the background baseline value of the non-reservoir segment based on the set of all window indices that meet the stationarity condition.

8. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 7, characterized in that, In S41, the expression for the Tg value sequence of the non-reservoir section is: ； In the formula, d1 represents the depth value of the first depth point, d2 represents the depth value of the second depth point, and d i d represents the depth value of the i-th depth point. P Let Tg1 represent the depth value at the Pth depth point, Tg2 represent the Tg value at the 1st depth point, and Tg3 represent the Tg value at the 2nd depth point. i Tg represents the Tg value corresponding to the i-th depth point. P This represents the Tg value corresponding to the Pth depth point; In S42, the mean The expression is: ； In the formula, w represents the fixed window length, and Tg i+k This indicates starting from the j-th Tg value and moving towards the k-th Tg value; In S43, the fluctuation amplitude σ j The expression is: ； In S44, the set of all window indices that satisfy the stationarity condition. The expression is: ； In the formula, τ represents the threshold for determining fluctuation, and j represents the starting index of the window; In S45, the expression for the background baseline value B of the non-reservoir section is: ； In the formula, ε represents a small constant to prevent division by zero.

9. The method for calculating the anomaly multiple of total hydrocarbons in gas chromatography according to claim 1, characterized in that, In step S5, the anomaly multiple of the reservoir section is calculated based on the ratio between the Tg value at each depth point of the reservoir section and the background baseline value of the non-reservoir section.

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