Method for establishing reservoir water trapping index and method for evaluating reservoir water trapping capacity

Abstract

The application discloses a method for establishing a reservoir water trapping index for characterizing the water trapping capacity of a reservoir, which comprises the following steps: obtaining a reservoir related data set comprising reservoir rock mineral composition data, reservoir fluid property data and pore structure data; determining data items that can be used to characterize the water trapping capacity of the reservoir according to the reservoir related data set; calculating a whole rock evaluation coefficient M and a gas logging evaluation coefficient G according to the data items; and constructing a reservoir water trapping index FS according to the whole rock evaluation coefficient M and the gas logging evaluation coefficient G. The reservoir water trapping index for characterizing the water trapping capacity of the reservoir is obtained by analyzing the relationship between the water loss of drilling fluid and cementing fluid and the rock mineral composition and the reservoir fluid property, and can be used for analyzing and judging the water content of different reservoirs, and for interpreting and evaluating the well wall stability and the easy cementing degree in the drilling and completion operation of petroleum engineering, thereby providing a decision basis for optimizing the drilling fluid and the cementing fluid. The application further discloses a method for evaluating the water trapping capacity of a reservoir based on the reservoir water trapping index.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical service field of logging engineering, drilling engineering, cementing engineering and the like, and particularly relates to a method for establishing a reservoir water trapping index for characterizing reservoir water trapping capacity and a method for evaluating reservoir water trapping capacity based on the reservoir water trapping index. BACKGROUND

[0002] In the process of oil and gas drilling and completion, the liquid column pressure of drilling fluid or cementing fluid is usually greater than the reservoir fluid pressure. Through the action of pressure difference, the drilling fluid or cementing fluid always leaks or filters into the reservoir pores, and at the same time, the reservoir rock also has a water trapping effect on the water in the liquid in the wellbore. The interaction of the two will cause the leakage phenomenon to occur.

[0003] The water loss process of the drilling fluid or cementing fluid in the well is the process of water in the drilling fluid or cementing fluid penetrating into the reservoir porous medium. The water loss of water-sensitive shale hydration expansion will cause the collapse of the reduced diameter; the water loss of the porous hydrophilic rock will relatively change the performance of the drilling fluid or cementing fluid; and the water loss of the large-pore rock will cause the well leakage. The water loss amount is closely related to the geological factors such as the mineral composition of the rock, the pore structure and the properties of the reservoir fluid.

[0004] However, there is currently no quantitative index that can comprehensively evaluate the reservoir water trapping capacity in view of the above influencing factors. The evaluation of the reservoir water trapping capacity is of great significance for the interpretation and evaluation of the wellbore stability and the cementing degree and the optimization of the drilling fluid and the cementing fluid in the oil engineering drilling and completion operation. In view of this, the prior art needs to be improved. SUMMARY

[0005] The present application aims at providing a method for establishing a reservoir water trapping index for characterizing reservoir water trapping capacity, a method for evaluating reservoir water trapping capacity based on the reservoir water trapping index and the application of the reservoir water trapping index in the oil engineering drilling and completion operation, so as to provide a quantitative index that can comprehensively evaluate the reservoir water trapping capacity, thereby improving the rapidity, convenience, accuracy and reliability of the evaluation of the reservoir water trapping capacity, so as to provide a decision basis for the analysis and judgment of different reservoir water content, the interpretation and evaluation of the wellbore stability and the cementing degree and the optimization of the drilling fluid and the cementing fluid in the oil engineering drilling and completion operation.

[0006] According to a first aspect of the present application, a method for establishing a reservoir water trapping index for characterizing reservoir water trapping capacity is provided, which comprises:

[0007] obtaining a reservoir related data set, the reservoir related data set comprising reservoir rock mineral composition data, reservoir fluid property data and pore structure data;

[0008] Based on the obtained reservoir-related dataset, determine the data items that can be used to characterize the reservoir's water trapping capacity;

[0009] Based on the determined data items, calculate the whole-rock evaluation coefficient M and the gas measurement evaluation coefficient G;

[0010] Based on the calculated whole-rock evaluation coefficient M and gas measurement evaluation coefficient G, the reservoir water trapping index FS is constructed.

[0011] According to one embodiment of the present invention, the data items determined that can be used to characterize the reservoir's water trapping capacity include: total hydrocarbon content in gas analysis, whole rock quartz content, whole rock feldspar content, and porosity.

[0012] According to one embodiment of the present invention, calculating the whole-rock evaluation coefficient M based on the determined data items includes: calculating the whole-rock hydrophilicity index m based on the whole-rock quartz percentage content and the whole-rock feldspar percentage content; fitting the whole-rock hydrophilicity index m with the corresponding porosity K to establish a functional relationship between the two, so as to obtain the whole-rock evaluation coefficient M.

[0013] Based on the percentage content of quartz and feldspar in the whole rock, the hydrophilicity index m of the whole rock is calculated using the following formula:

[0014] m i = SY i + CS i , i =1,2,3,...,n,

[0015] in, m i For the first i Whole-rock hydrophilicity index values ​​of each sample. SY i For the first i The percentage of whole rock quartz in each sample. CS i For the first i The percentage of feldspar in the whole rock of each sample. n The total number of samples from the reservoir.

[0016] The functional relationship between porosity K and whole-rock hydrophilicity index m obtained using the Gaussian model is as follows:

[0017] in, K i Let be the porosity value of the i-th sample. M Whole rock evaluation coefficient ，m i Let be the whole-rock hydrophilicity index of the i-th sample. y0 、w、 mc These are the parameters to be estimated in the analytical expression of the fitted curve.

[0018] According to one embodiment of the present invention, calculating the gas measurement evaluation coefficient G based on the determined data items includes: calculating the gas measurement evaluation coefficient G based on the total hydrocarbon value and the porosity.

[0019] According to one embodiment of the present invention, calculating the gas measurement evaluation coefficient G based on the total hydrocarbon value and the porosity includes:

[0020] Based on the measured total hydrocarbon values, calculate the total hydrocarbon peak-to-average ratio (FJ). 全烃 :

[0021] For the total hydrocarbon peak average ratio FJ 全烃 After normalization, the hydrophilicity index value W of the total hydrocarbon peak average ratio is obtained:

[0022] The relationship between the hydrophilicity index W of the total hydrocarbon peak average ratio and the corresponding porosity K is established by fitting the two to obtain the porosity K expressed as a function of the hydrophilicity index W of the total hydrocarbon peak average ratio, which is the gas measurement evaluation coefficient G.

[0023] According to one embodiment of the present invention, the peak-to-average ratio (FJ) of all hydrocarbons is calculated based on the gas-measured total hydrocarbon value using the following formula. 全烃 :

[0024] i=1,2,3,...,n

[0025] in, FJ i全烃 For the first i The average peak value of total hydrocarbons for each sample. QT i For the first i Total hydrocarbon values ​​measured for each sample. n This represents the total number of samples from the reservoir.

[0026] The hydrophilicity index W of the total hydrocarbon peak-to-average ratio is calculated using the following formula:

[0027] W i =1- FJ i全烃 * k，

[0028] in, W i Let be the hydrophilic index value of the total hydrocarbon peak average ratio for the i-th sample. k These are the conversion factors;

[0029] The functional relationship between the hydrophilicity index W and porosity K of the total hydrocarbon peak-to-average ratio, obtained using the Savitzky-Golay model, is as follows:

[0030] ,

[0031] Right now, ,

[0032] in, G i Let be the gas measurement evaluation coefficient value of the i-th sample. K i Let be the porosity value of the i-th sample. b ni represents the convolution coefficient.

[0033] According to one embodiment of the present invention, the conversion coefficient k The peak-to-average ratio of all hydrocarbons was obtained based on the normal distribution of the numerical range.

[0034] According to one embodiment of the present invention, the conversion coefficient k It is 1 / 3.

[0035] According to one embodiment of the present invention, the reservoir water capture index FS is constructed by multiplying the whole-rock evaluation coefficient M with the gas measurement evaluation coefficient G.

[0036] According to one embodiment of the present invention, the method further includes establishing an evaluation criterion for characterizing the reservoir's water-capturing capacity using the water-capturing index FS.

[0037] According to one embodiment of the present invention, an evaluation standard for characterizing the reservoir's water-trapping capacity is established by taking the industry porosity interval classification standard as a reference and combining the correlation curve morphology characteristics of the whole-rock hydrophilicity index m and the hydrophilicity index W of the total hydrocarbon peak-to-average ratio with porosity.

[0038] According to one embodiment of the present invention, establishing evaluation criteria includes:

[0039] Establish porosity range divisions;

[0040] Determine the value of the whole-rock evaluation coefficient M within the porosity interval division and determine the value of the gas measurement evaluation coefficient G within the porosity interval division;

[0041] Based on the determined values, the range of the reservoir water capture index FS is calculated, and the interval for evaluating the reservoir water capture capacity is divided according to the range of the reservoir water capture index FS.

[0042] According to one embodiment of the present invention, the evaluation criterion for characterizing the reservoir's water-trapping capacity using the reservoir water-trapping index FS is as follows:

[0043] When the reservoir water capture index FS is 0 to 100, the reservoir water capture capacity is determined to be weak.

[0044] When the reservoir water capture index FS is 100-240, the reservoir water capture capacity is determined to be medium.

[0045] When the reservoir water capture index (FS) is between 240 and 383, the reservoir is considered to have strong water capture capacity.

[0046] According to a second aspect of the present invention, a method for evaluating the water-trapping capacity of a reservoir based on a reservoir water-trapping index is provided, characterized in that the reservoir water-trapping index is established using the aforementioned method for establishing a reservoir water-trapping index, and the method for evaluating the reservoir water-trapping capacity includes: obtaining the total hydrocarbon value of the reservoir gas path; calculating the reservoir water-trapping index FS based on the obtained total hydrocarbon value of the reservoir gas path; and evaluating the reservoir water-trapping capacity based on the calculated reservoir water-trapping index FS and referring to the evaluation criteria of the reservoir water-trapping index FS.

[0047] According to one embodiment of the present invention, calculating the reservoir water trapping index FS based on the obtained total hydrocarbon values ​​obtained from the gas logging of the reservoir includes: calculating the hydrophilic index W of the peak-to-average ratio of total hydrocarbons based on the obtained total hydrocarbon values ​​obtained from the gas logging of the reservoir; calculating the gas logging evaluation coefficient G based on the hydrophilic index W of the peak-to-average ratio of total hydrocarbons; determining the whole-rock evaluation coefficient M based on the correspondence between the whole-rock evaluation coefficient M and the hydrophilic index W of the peak-to-average ratio of total hydrocarbons; and multiplying the calculated gas logging evaluation coefficient G by the determined whole-rock evaluation coefficient M to obtain the reservoir water trapping index FS.

[0048] According to one embodiment of the present invention, when the calculated reservoir water capture index FS is 0 to 100, the reservoir water capture capacity is determined to be weak; when the calculated reservoir water capture index FS is 100 to 240, the reservoir water capture capacity is determined to be moderate; and when the calculated reservoir water capture index FS is 240 to 383, the reservoir water capture capacity is determined to be strong.

[0049] According to one embodiment of the present invention, multiple reservoir water capture indices of the reservoir are obtained by interval sampling, and the average value of the multiple reservoir water capture indices is calculated. The water capture capacity of the reservoir is evaluated based on the average value of the multiple reservoir water capture indices.

[0050] According to a third aspect of the present invention, an application of the reservoir water capture index established by the above method in oil drilling and completion operations is provided.

[0051] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0052] By constructing a reservoir water trapping index, the ability of various rocks in the drilled reservoir to trap water in the well fluid and the permeability of rock pores to the well fluid were comprehensively evaluated. Based on the magnitude of the constructed reservoir water trapping index, the water trapping capacity of the reservoir can be quantitatively characterized, enabling rapid evaluation of the reservoir water trapping capacity and improving the reliability and accuracy of the evaluation.

[0053] The reservoir water trapping index constructed using this invention tests historical well data and newly drilled wells in the field. The parameter characteristics are highly consistent with the wellbore leakage, which can well characterize the reservoir water trapping capacity level. It can also be used to guide cementing operations to effectively improve cementing quality. It can be used to analyze and judge the water content of different reservoirs in oil drilling and completion operations, interpret and evaluate wellbore stability and cementing ease, and provide a decision-making basis for optimizing drilling fluid and cementing fluid. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a flowchart of the method for establishing the reservoir water trapping index provided in this embodiment of the invention;

[0056] Figure 2 The curve showing the fit between the whole-rock hydrophilicity index m and porosity;

[0057] Figure 3 The fitted curve of the hydrophilicity index W, which is the ratio of porosity to the peak average of all hydrocarbons;

[0058] Figure 4 A flowchart of a method for evaluating reservoir water trapping capacity based on a reservoir water trapping index provided in this embodiment of the invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0060] It should be noted that the specific structure, features, and advantages of the present invention will be illustrated by examples below. However, all descriptions are for illustrative purposes only and should not be construed as limiting the present invention in any way. Furthermore, any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the accompanying drawings, can still be arbitrarily combined or deleted among these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned herein.

[0061] like Figure 1 As shown, this embodiment of the invention provides a method for establishing a reservoir water trapping index, which characterizes the water trapping capacity of a reservoir, and includes the following steps:

[0062] S100: Obtain reservoir-related datasets, which include reservoir rock and mineral composition data, reservoir fluid property data, and pore structure data.

[0063] S200: Based on the acquired reservoir-related dataset, determine the data items that can be used to characterize the reservoir's water-trapping capacity.

[0064] S300: Based on the determined data items, calculate the whole-rock evaluation coefficient M and the gas measurement evaluation coefficient G. The whole-rock evaluation coefficient M characterizes the ability of rock mineral components to trap water, while the gas measurement evaluation coefficient G characterizes the permeability of rock pores to water.

[0065] S400: Based on the calculated whole-rock evaluation coefficient M and gas measurement evaluation coefficient G, the reservoir water trapping index FS is constructed.

[0066] Step S100 includes: acquiring logging data and reservoir pore structure data through integrated logging tools, whole-rock logging tools (also known as elemental logging tools), and manual acquisition; classifying and organizing the acquired logging data and reservoir pore structure data to form a logging interpretation database. It should be noted that the acquired reservoir-related data dataset includes a sufficient number of statistically significant reservoir samples.

[0067] In step S200, the data items determined that can be used to characterize the reservoir's water-trapping capacity include: total hydrocarbon content in gas logging, whole-rock quartz percentage content, whole-rock feldspar percentage content, and porosity. The total hydrocarbon content in gas logging can be obtained using a comprehensive logging tool, expressed as % or ppm; the whole-rock quartz percentage content and whole-rock feldspar percentage content can be obtained through whole-rock logging (also known as elemental logging), expressed as %; and reservoir porosity can be obtained through manual collection.

[0068] The water-capturing capacity of rock minerals is an important factor affecting the water-capturing capacity of reservoirs. Related studies have shown that quartz and feldspar are the most important hydrophilic rock minerals in reservoirs and have a significant impact on water-capturing capacity. Therefore, the content of feldspar and quartz in reservoirs can be used to quantitatively characterize the water-capturing capacity of rock minerals.

[0069] Meanwhile, the water permeability of rock pores is another important factor affecting the water trapping capacity of reservoirs. As is well known, the pore spaces of underground reservoir rocks are filled with different fluids. The more hydrocarbons carried by the drilling fluid and the higher the total hydrocarbon content, the more hydrocarbons are present in the reservoir rock pores, which means that the ability to allow water to permeate into the reservoir is weaker. Therefore, the hydrocarbons carried by the drilling fluid (i.e., the total hydrocarbon value measured by gas logging) can be used to quantitatively characterize the water trapping capacity of rock pores.

[0070] It should be noted that while porosity data can reflect the potential ability of rock pores to trap water to a certain extent, this data does not have the characteristic of being measured in real time during drilling. Therefore, this invention uses gas-based total hydrocarbon values, which are more timely and can be measured in real time during drilling, to characterize the ability of rock pores to trap water.

[0071] This invention, based on a comprehensive consideration of the water-capturing capacity of rock mineral components and the water-permeability of rock pores, uses whole-rock analysis obtained during drilling to characterize the water-capturing capacity of rock mineral components, and uses real-time measured total hydrocarbon values ​​to characterize the water-permeability of rock pores. The values ​​obtained by performing corresponding calculations on these two data points are used to quantitatively characterize the reservoir's water-capturing capacity, thereby achieving the purpose of timely guidance and optimization of drilling and completion operation plans.

[0072] Step S300 includes: calculating the whole-rock hydrophilicity index m based on the whole-rock quartz percentage and whole-rock feldspar percentage using the following formula:

[0073] m i = SY i + CS i , i =1,2,3...,n formula 1

[0074] in, m i For the first i Whole-rock hydrophilicity index values ​​of each sample. SY i For the first i The percentage of whole rock quartz in each sample. CS i For the first iThe percentage of feldspar in the whole rock of each sample. n This represents the total number of samples from the reservoir.

[0075] Step S300 includes: fitting the whole-rock hydrophilicity index m with the corresponding porosity K to establish a functional relationship between the two, so as to obtain the whole-rock evaluation coefficient M. Specifically, the whole-rock hydrophilicity index m and the corresponding porosity K are fitted using a Gaussian model to establish the relationship between them, resulting in the following analytical expression:

[0076] Formula 2

[0077] in, K i Let be the porosity value of the i-th sample. M Whole rock evaluation coefficient ，m i Let be the whole-rock evaluation coefficient value of the i-th sample. y 0 , w, mc These are the parameters to be estimated in the analytical expression of the fitted curve. The fitted curve is as follows: Figure 2 As shown.

[0078] Step S300 includes: calculating the gas measurement evaluation coefficient G based on the total hydrocarbon value and porosity. Specifically, based on the total hydrocarbon value, the peak-to-average ratio FJ of the total hydrocarbons is calculated using the following formula. 全烃 :

[0079] Formula 3: i=1,2,3...,n

[0080] in, FJ i全烃 For the first i The average peak value of total hydrocarbons for each sample. QT i For the first i Total hydrocarbon values ​​measured for each sample. n This represents the total number of samples from the reservoir.

[0081] Big data analysis shows that the higher the peak-to-average ratio (PAR) of the total hydrocarbons in a reservoir, the weaker its hydrophilicity and the stronger its non-hydrophilicity. To eliminate the influence of extreme values ​​on the overall pattern, based on the normal distribution of the PAR values, values ​​with a PAR ≤ 3 account for more than 95% of the total hydrocarbons. Therefore, the maximum range of the PAR is defined as 3. Based on this, the PAR FJ is derived. 全烃 The conversion factor is 1 / 3, and the peak-to-average power ratio (PAPR) FJ is calculated. 全烃 The non-hydrophilic index value is FJ 全烃 *0.3333, then the formula for calculating the hydrophilicity index value of the total hydrocarbon peak average ratio is:

[0082] W i =1-FJ i全烃 *0.3333Formula 4

[0083] in, W i denoted as the hydrophilic index value of the total hydrocarbon peak average ratio for the i-th sample.

[0084] The relationship between the hydrophilic index W (peak-to-average ratio of total hydrocarbons) and the corresponding porosity value K was established by fitting the Savitzky-Golay model, resulting in the porosity value K expressed as a function of the hydrophilic index W (peak-to-average ratio of total hydrocarbons):

[0085] Formula 5

[0086] in, K i Let be the porosity value of the i-th sample. b ni The convolution coefficients are used. The fitted curve is shown below. Figure 3 As shown.

[0087] This relationship can also be used to characterize the gas measurement evaluation coefficient. To facilitate discussion and differentiation from porosity, the relationship is defined as G. i G i Let be the gas measurement evaluation coefficient value for the i-th sample, and then we obtain the following formula:

[0088] Formula 6

[0089] Step S400 involves multiplying the whole-rock evaluation coefficient M by the gas measurement evaluation coefficient G to construct the reservoir water trapping index FS. FS i = M i * G i Using the whole-rock evaluation coefficient M as the influence coefficient of the water trapping index, the formula for the reservoir water trapping index is as follows:

[0090] Formula 7, i=1,2,3,...n

[0091] in, FS i Let be the water trapping index value of the i-th sample. M i Let be the whole-rock evaluation coefficient value of the i-th sample. b ni The convolution coefficients are... n This represents the total number of samples.

[0092] Based on the multiplication principle: if there is a direct proportional relationship between the dependent variable f and the independent variables x1, x2, x3, ..., xn, and each independent variable is qualitatively different, the dependent variable f loses its meaning if any independent variable is missing, then the relationship between the independent variables should be multiplicative. In this invention, since there is a direct functional relationship between the reservoir water-trapping capacity (i.e., the constructed reservoir water-trapping index FS) as the dependent variable and the whole-rock evaluation coefficient M and gas measurement evaluation coefficient G as the independent variables, and the meanings of the two independent variable parameters are essentially different, the dependent variable will lose its accurate characterization meaning if either of the two independent variables is missing. Therefore, this invention uses the method of multiplying the independent variables to proportionally amplify the parameter characterization features.

[0093] The method for establishing a reservoir water-trapping index (FS) to characterize reservoir water-trapping capacity also includes establishing an evaluation standard for the FS to characterize reservoir water-trapping capacity. In one embodiment, the evaluation standard for the FS is reasonably defined based on the industry porosity interval division standard and the correlation curve morphology of the whole-rock hydrophilicity index m and the hydrophilicity index W (peak-to-average ratio of total hydrocarbons) with porosity. Specifically, firstly, the porosity interval division is established; then, the values ​​of the whole-rock evaluation coefficient M and the gas logging evaluation coefficient G within the porosity interval division are determined; finally, based on the determined values, the range of the reservoir water-trapping index FS is calculated, and the interval for evaluating the reservoir water-trapping capacity using the FS is divided according to the range of the FS.

[0094] Referring to Table 1, according to the industry standard "Petroleum and Natural Gas Industry Standard of the People's Republic of China SY / T6285-2011, Oil and Gas Reservoir Evaluation Method", reservoir porosity is divided into six types: ultra-high porosity, high porosity, medium porosity, low porosity, ultra-low porosity, and extra-low porosity. Based on the geological characteristics of the study area where reservoir porosity is generally between 15% and 30%, this invention mainly studies the water-trapping capacity of reservoirs with porosity between 15% and 30% and establishes interpretation and evaluation standards. Furthermore, in this invention, when the porosity is between 15% and 20% and between 20% and 25%, the whole-rock hydrophilicity index m and the hydrophilicity index W of the total hydrocarbon peak-to-average ratio exhibit different interval patterns. Therefore, the medium-porosity segment of 15% to 25% in the reservoir porosity type is further subdivided into two intervals: 15% to 20% and 20% to 25%, for separate consideration. Therefore, in this invention, when establishing evaluation criteria, porosity is divided into three intervals: 15%–20%, 20%–25%, and 25%–30%.

[0095] Table 1 Classification of porosity types in clastic rock reservoirs

[0096]

[0097] When the porosity K is between 15% and 20%, the parameters to be estimated in the analytical expression of the fitted curve in Formula 2 are y0=58.7470±8.199, A=5.6714±0.3154, and w=3.4654±2.1154, respectively; when the porosity K is between 20% and 25%, the parameters to be estimated in the analytical expression of the fitted curve are y0=58.7470±8.100, A=7.0499±0.5204, and w=3.2493±2.9433; when the porosity K is between 25% and 30%, y0=58.7470±8.1900, A=6.9271±1.5436, and w=5.4021±8.6373.

[0098] Using the corresponding analytical formula, the values ​​of the whole-rock evaluation coefficient M in different porosity ranges are as follows: when the porosity K is between 15% and 20%, the median integral value of M is 5.67 ± 0.32; when the porosity K is between 20% and 25%, the median integral value of M is 7.05 ± 0.52; and when the porosity K is between 25% and 30%, the median integral value of M is 6.93 ± 1.54.

[0099] Substituting the corresponding interval values ​​of the whole-rock evaluation coefficient M into the water trapping index formula (i.e., Formula 7), we obtain: when the porosity K is 15% to 20%, FS is (89 to 109) ± 97, with an error range of 0 to 206, and a confidence level of 100%; FS is 0 to 100, indicating weak water trapping; when the porosity K is 20% to 25%, FS is (132 to 168) ± 152, with an error range of 0 to 336, and a confidence level of 100%, FS is 100 to 240, indicating moderate water trapping; when the porosity K is 25% to 30%, FS is (161 to 199) ± 184, with an error range of 0 to 383, and a confidence level of 100%, FS is (240 to 383), indicating strong water trapping.

[0100] Based on the research findings of this invention, there is a certain functional relationship between the hydrophilic index W (peak-to-average ratio of total hydrocarbons) and the corresponding porosity K (i.e., Formula 5). By correlating different porosity ranges with the ranges of the hydrophilic index W, we can obtain the following: when the porosity K is 15%–20%, W < 0.72; when the porosity K is 20%–25%, W is between 0.72 and 0.95; and when the porosity K is 25%–30%, W > 0.95. Therefore, based on the correspondence between porosity and the whole-rock evaluation coefficient M and the hydrophilic index W, we can determine that when W < 0.72, the value of M is 5.67 ± 0.32; when W is between 0.72 and 0.95, the value of M is 7.05 ± 0.52; and when W > 0.95, the value of M is 6.93 ± 1.54. Based on this, a correspondence between the whole-rock evaluation coefficient M and the hydrophilicity index W (peak-to-average ratio of total hydrocarbons) was established using porosity as a parameter medium. The value of the whole-rock evaluation coefficient M was calculated from the range of the hydrophilicity index W (peak-to-average ratio of total hydrocarbons).

[0101] like Figure 4 As shown, this embodiment of the invention provides a method for evaluating the water-trapping capacity of a reservoir based on a reservoir water-trapping index. The reservoir water-trapping index is established using the method described above. The method for evaluating the water-trapping capacity of a reservoir includes the following steps:

[0102] S1000: Obtain the total hydrocarbon value of the reservoir gas logging. Specifically, the total hydrocarbon value can be obtained in real time using a comprehensive logging tool. Multiple total hydrocarbon values ​​are required for calculation.

[0103] S2000: Calculate the reservoir water trapping index FS based on the acquired parameters. Specifically, first, calculate the hydrophilic index W of the total hydrocarbon peak-to-average power ratio according to formulas 3 and 4. Then, determine the value of the whole-rock evaluation coefficient M based on the correspondence between the whole-rock evaluation coefficient M and the hydrophilic index W of the total hydrocarbon peak-to-average power ratio (when W < 0.72, the value of M is 5.67 ± 0.32; when W is between 0.72 and 0.95, the value of M is 7.05 ± 0.52; when W > 0.95, the value of M is 6.93 ± 1.54). Then, based on the determined value of the whole-rock evaluation coefficient M and the calculated hydrophilic index W of the total hydrocarbon peak-to-average power ratio, calculate the reservoir water trapping index FS according to formula 7.

[0104] S3000: The reservoir's water-trapping capacity is evaluated based on the calculated reservoir water-trapping index FS and the evaluation criteria for FS. Specifically, when the calculated reservoir water-trapping index FS is 0–100, the reservoir's water-trapping capacity is determined to be weak; when the calculated water-trapping index FS is 100–240, the reservoir's water-trapping capacity is determined to be moderate; and when the calculated water-trapping index FS is 240–383, the reservoir's water-trapping capacity is determined to be strong.

[0105] To increase the accuracy of the reservoir water trapping index, multiple reservoir water trapping indices can be obtained by interval sampling, and the average value of the multiple reservoir water trapping indices can be calculated to evaluate the reservoir's water trapping capacity.

[0106] To further verify the effectiveness of the reservoir water trapping index provided by this invention in evaluating reservoir water trapping capacity and guiding cementing operations, historical well data and field test wells were tested using the method of this invention. The sample results show that the reservoir water trapping index provided by this invention effectively improves cementing quality during cementing operations, increasing the cementing quality rate by more than 20%, and has a high correlation with the loss of drilling fluid in a single well. It well characterizes the water trapping capacity level of the reservoir and guides cementing operations, providing an important reference for the design of cementing fluid and drilling fluid schemes in reservoir comprehensive logging interpretation and evaluation.

[0107] As an example, in one embodiment, the water trapping index of the reservoir section of well TD12X1 is calculated. It should be noted that in order to increase the accuracy of the reservoir water trapping index, multiple reservoir water trapping indices are obtained by taking samples at intervals, and the average value of multiple reservoir water trapping indices is calculated. Specifically, a sample is taken every 1 meter along the well depth, and the parameters of total hydrocarbon evaluation parameters and total rock evaluation coefficient are obtained by the instrument. Multiple water trapping indices are calculated and finally obtained, and the average value of multiple water trapping indices is obtained. The value of the water trapping index is verified by the well leakage and cementing quality. The specific details are shown in Table 2 below.

[0108] Table 2 Comparison Table of Reservoir Water Capture Index, Cementing Quality, and Actual Drilled Well Loss Record

[0109]

[0110] As shown in Table 2, well sections with high reservoir water capture index and medium water capture level had a higher proportion of poorly cemented cement slurry thickness; conversely, well sections with low reservoir water capture index and weak water capture level had a lower proportion of poorly cemented cement slurry thickness. Well leakage occurred in well sections with high reservoir water capture index and medium water capture level, but not in well sections with low reservoir water capture index and weak water capture level.

[0111] As an example, we statistically analyzed two single wells before and after cementing construction guidance, calculated the water capture index of different grades of well sections and thicknesses in the same geological stratum, and verified the effects before and after cementing construction guidance. The specific details are shown in Table 3 below.

[0112] Table 3 Comparison of the Implementation Effects of Water Capture Index Guiding Cementing Scheme Optimization

[0113]

[0114] As can be seen from Table 3, for the single well sections with high water capture index in the example wells, the implementation of optimization schemes in cementing operations has achieved high cementing qualification rate and quality rate. However, for single wells without cementing scheme guidance and optimization, the overall cementing qualification rate and quality rate are relatively low.

[0115] This shows that the reservoir water trapping index can be used to interpret and evaluate the water trapping capacity of a reservoir and to guide the improvement and optimization of cementing fluid and drilling fluid scheme design.

[0116] The above are exemplary embodiments disclosed in this invention. The order of the disclosed embodiments is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. However, it should be noted that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of this invention (including the claims) is limited to these examples. Various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular.

[0117] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for establishing a reservoir water trapping index to characterize the water trapping capacity of a reservoir, characterized in that, include: Obtain reservoir-related datasets, which include reservoir rock and mineral composition data, reservoir fluid property data, and pore structure data; Based on the obtained reservoir-related dataset, data items that can be used to characterize the reservoir's water trapping capacity were identified. These data items include: total hydrocarbon content in gas analysis, whole rock quartz content, whole rock feldspar content, and porosity. The whole rock hydrophilicity index m is calculated based on the whole rock quartz percentage and the whole rock feldspar percentage. The whole rock hydrophilicity index m is fitted with the corresponding porosity K to establish a functional relationship between the two, so as to obtain the whole rock evaluation coefficient M. Based on the measured total hydrocarbon values, calculate the total hydrocarbon peak-to-average ratio (FJ). 全烃 For the total hydrocarbon peak average ratio FJ 全烃 Normalization is performed to obtain the hydrophilic index value W of the total hydrocarbon peak average ratio. The hydrophilic index W of the total hydrocarbon peak average ratio is fitted with the corresponding porosity K to establish the relationship between the two, so as to obtain the porosity K expressed by the function of the hydrophilic index W of the total hydrocarbon peak average ratio, which is the gas measurement evaluation coefficient G. The reservoir water trapping index FS is constructed by multiplying the whole-rock evaluation coefficient M with the gas measurement evaluation coefficient G.

2. The method for establishing the reservoir water trapping index, which characterizes the water trapping capacity of a reservoir, according to claim 1, is characterized in that, Based on the percentage content of quartz and feldspar in the whole rock, the hydrophilicity index m of the whole rock is calculated using the following formula: m i = SY i + CS i ， i =1,2,3...,n， in, m i For the first i Whole-rock hydrophilicity index values ​​of each sample. SY i For the first i The percentage of whole rock quartz in each sample. CS i For the first i The percentage of feldspar in the whole rock of each sample. n The total number of samples from the reservoir. The functional relationship between porosity K and whole-rock hydrophilicity index m obtained using the Gaussian model is as follows: in, K i Let be the porosity value of the i-th sample. M Whole rock evaluation coefficient ，m i Let be the whole-rock hydrophilicity index of the i-th sample. y 0 w, mc These are the parameters to be estimated in the analytical expression of the fitted curve.

3. The method for establishing a reservoir water trapping index characterizing the reservoir's water trapping capacity according to claim 1, characterized in that, Based on the measured total hydrocarbon values, the peak-to-average power ratio (FJ) of the total hydrocarbons is calculated using the following formula. 全烃 : i=1,2,3...,n, in, FJ i全烃 For the first i The average peak value of total hydrocarbons for each sample. QT i For the first i Total hydrocarbon values ​​measured for each sample. n This represents the total number of samples from the reservoir. The hydrophilicity index W of the total hydrocarbon peak-to-average ratio is calculated using the following formula: W i =1- FJ i全烃 * k， in, W i Let be the hydrophilic index value of the total hydrocarbon peak average ratio for the i-th sample. k These are the conversion factors; The functional relationship between the hydrophilicity index W and porosity K of the total hydrocarbon peak-to-average ratio, obtained using the Savitzky-Golay model, is as follows: ， Right now, , in, G i Let be the gas measurement evaluation coefficient value of the i-th sample. K i Let be the porosity value of the i-th sample. b ni represents the convolution coefficient.

4. The method for establishing the reservoir water trapping index, which characterizes the water trapping capacity of a reservoir, according to claim 3, is characterized in that... The conversion coefficient k The peak-to-average ratio of all hydrocarbons was obtained based on the normal distribution of the numerical range.

5. The method for establishing a reservoir water trapping index characterizing the reservoir's water trapping capacity according to claim 4, characterized in that, The conversion coefficient k It is 1 / 3.

6. The method for establishing a reservoir water trapping index characterizing the water trapping capacity of a reservoir according to claim 1, characterized in that, It also includes establishing an evaluation standard that uses the water capture index (FS) to characterize the reservoir's water capture capacity.

7. The method for establishing a reservoir water trapping index characterizing the reservoir's water trapping capacity according to claim 6, characterized in that, Based on the industry's porosity range classification standard and combined with the correlation curve morphology of the whole-rock hydrophilic index m and the hydrophilic index W (peak-to-average ratio of total hydrocarbons) with porosity, an evaluation standard using the water-capturing index FS to characterize the reservoir's water-capturing capacity is established.

8. The method for establishing a reservoir water trapping index characterizing the reservoir's water trapping capacity according to claim 7, characterized in that, The evaluation criteria include: Establish porosity range divisions; Determine the value of the whole-rock evaluation coefficient M within the porosity interval division and determine the value of the gas measurement evaluation coefficient G within the porosity interval division; Based on the determined values, the range of the reservoir water capture index FS is calculated, and the interval for evaluating the reservoir water capture capacity is divided according to the range of the reservoir water capture index FS.

9. The method for establishing a reservoir water trapping index characterizing the reservoir's water trapping capacity according to claim 6, characterized in that, The evaluation criteria for characterizing the reservoir's water trapping capacity using the reservoir water trapping index (FS) are as follows: When the reservoir water capture index FS is 0 to 100, the reservoir water capture capacity is determined to be weak. When the reservoir water capture index FS is 100-240, the reservoir water capture capacity is determined to be medium. When the reservoir water capture index (FS) is between 240 and 383, the reservoir is considered to have strong water capture capacity.

10. A method for evaluating the water-trapping capacity of a reservoir based on a reservoir water-trapping index, characterized in that, The reservoir water trapping index is established using the method for establishing the reservoir water trapping index according to any one of claims 1-9, and the method for evaluating the reservoir water trapping capacity includes: Obtain the total hydrocarbon values ​​from the reservoir gas analysis; The hydrophilicity index W of the total hydrocarbon peak-to-average ratio is calculated based on the obtained total hydrocarbon values ​​from the reservoir gas analysis. The gas measurement evaluation coefficient G is calculated based on the hydrophilic index W of the total hydrocarbon peak average ratio. The whole-rock evaluation coefficient M is determined based on the correspondence between the whole-hydrocarbon peak-to-average ratio and the hydrophilic index W. The calculated gas measurement evaluation coefficient G is multiplied by the determined whole-rock evaluation coefficient M to obtain the reservoir water trapping index FS. Based on the calculated reservoir water capture index FS, and referring to the evaluation criteria of the reservoir water capture index FS, the reservoir water capture capacity is evaluated.

11. The method for evaluating reservoir water trapping capacity based on the reservoir water trapping index according to claim 10, characterized in that, When the calculated reservoir water capture index FS is 0-100, the reservoir water capture capacity is determined to be weak; when the calculated reservoir water capture index FS is 100-240, the reservoir water capture capacity is determined to be moderate; when the calculated reservoir water capture index FS is 240-383, the reservoir water capture capacity is determined to be strong.

12. The method for evaluating reservoir water trapping capacity based on the reservoir water trapping index according to claim 10, characterized in that, Multiple water-capturing indices of the reservoir are obtained by interval sampling, and the average value of the water-capturing indices is calculated. The water-capturing capacity of the reservoir is evaluated based on the average value of the water-capturing indices.

13. An application of a reservoir water trapping index in petroleum engineering drilling and completion operations, characterized in that, The reservoir water capture index is established using the method for establishing the reservoir water capture index as described in any one of claims 1-9.

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