A well-seismic integrated horizontal well geosteering risk evaluation method

Abstract

The present application relates to unconventional oil and gas exploration technology field, specifically relates to a kind of well seismic integration horizontal well geosteering risk evaluation method.The present application relates to unconventional oil and gas exploration technology field, specifically relates to a kind of well seismic integration horizontal well geosteering risk evaluation method. DCCZ , well seismic error risk index R JZWC , curvature development degree risk index R QLFY ;Stratigraphic occurrence change risk index R BZC , logging parameter combination change feature risk index R LJCS , target window height risk index R BCGD ;Establish well seismic integration comprehensive risk index mathematical model and evaluation standard, mathematical model includes multiplication effect comprehensive risk index mathematical model and grey correlation weight coefficient comprehensive risk index mathematical model;Combined with the evaluation results of two mathematical models, the geosteering risk grade of the well to be evaluated is output.The present application can accurately evaluate geosteering risk, effectively improve reservoir drilling rate, reduce the risk of drilling target layer in geosteering, and avoid drilling engineering complexity.

Description

Technical Field

[0001] This invention relates to the field of unconventional oil and gas exploration technology, specifically to a method for geological steering risk assessment of horizontal wells that integrates well and seismic testing. Background Technology

[0002] With the rapid development of unconventional oil and gas exploration and development technologies such as shale gas, shale oil, and tight gas, exploration targets are expanding to areas with deeper burial, more complex geological structures, and greater development difficulties. This has led to a significant increase in the risks of drilling out the target layer during geological steering and the complexity of downhole engineering. In extreme cases, well-filling and sidetracking may even occur, resulting in wasted investment and poor exploration and development results.

[0003] Geological steering work is divided into three processes: pre-drilling preparation, in-drilling adjustment, and post-drilling summary. Among them, geological steering risk assessment and solution technology are important components of pre-drilling preparation. Since geological steering risk analysis needs to consider many factors, the commonly used method is for technicians to conduct geological steering risk assessment and formulate corresponding solution technology based on the target well design and adjacent well drilling data collected before drilling. However, this analysis method is easily limited by the extent to which the analysts have obtained the data before drilling and their subjective understanding of the target well design. It is difficult to comprehensively evaluate the risks faced during geological steering adjustments during drilling, which affects the overall benefits of unconventional horizontal well exploration and development.

[0004] Therefore, there is an urgent need to establish a simple, scientific and reasonable integrated well-seismic geological guidance risk assessment method to lay the foundation for the efficient development of horizontal wells in unconventional oil and gas reservoirs such as shale gas, shale oil, and tight gas. Summary of the Invention

[0005] The purpose of this invention is to address the various factors affecting drilling success rates and the low-probability but significant sidetracking risks in existing technologies during geological steering processes. It provides an integrated well-seismic risk assessment method for horizontal wells, based on a comprehensive risk index model and evaluation criteria using geophysical and seismic interpretation and drilling geological risk assessment parameters. This method achieves accurate assessment of geological steering risks, is simple to operate, scientifically sound, and facilitates the development of contingency plans. It lays the foundation for the efficient development of horizontal wells in unconventional oil and gas reservoirs such as shale gas, shale oil, and tight gas, while reducing the difficulty of engineering implementation.

[0006] This invention discloses an integrated well-seismic geological steering risk assessment method for horizontal wells, comprising the following steps:

[0007] Obtain geophysical and seismic interpretation information and relevant drilling geological parameters of the well to be evaluated;

[0008] Calculate the formation attitude change risk index R of the well to be evaluated DCCZ Well vibration error risk index R JZWCCurvature development degree risk index R QLFY ;

[0009] Determine the risk index R of the geological steering reference marker layer of the well to be evaluated. BZC Risk index R of changes in logging parameter combinations LJCS Target window height risk index R BCGD ;

[0010] A mathematical model and evaluation standard for an integrated well-seismic risk index are established. The mathematical model includes a multiplicative effect integrated risk index mathematical model and a grey relational weight coefficient integrated risk index mathematical model.

[0011] The evaluation results of the comprehensive risk index mathematical model combining the multiplier effect and the comprehensive risk index mathematical model with the grey relational weight coefficient are used to output the geological steering risk level of the well to be evaluated.

[0012] If both mathematical models conclude that the risk level is Class I low risk, then the output risk level will be Class I low risk.

[0013] If either of the evaluation conclusions of the two mathematical models is Class I low risk and the other is Class II medium risk, or if both of the evaluation conclusions of the two mathematical models are Class II medium risk, or if either of the evaluation conclusions of the two mathematical models is Class I low risk and the other is Class III high risk, then the output risk level is Class II medium risk.

[0014] If both mathematical models conclude that the risk level is Class III (high risk), or if one of the mathematical models concludes that the risk level is Class II (medium risk) and the other concludes that the risk level is Class III (high risk), then the output risk level will be Class III (high risk).

[0015] Preferably, the acquisition of geophysical and seismic interpretation information and related drilling geological parameter data of the well to be evaluated includes:

[0016] Obtain geophysical and seismic interpretation information of the well to be evaluated, including changes in stratigraphic attitude, well-seismic error, and degree of curvature development;

[0017] Obtain relevant drilling geological parameter data for the well to be evaluated, including geological steering reference marker layers, characteristics of changes in logging parameter combinations, and target window height;

[0018] The stratigraphic attitude variation refers to the maximum variation of the stratigraphic dip angle along the designed trajectory direction of the horizontal segment of the target layer, obtained from geophysical and seismic interpretation.

[0019] The well seismic error refers to the difference between the target layer depth obtained from the drilled well and the target layer depth interpreted by geophysical seismic exploration. It is calculated using data obtained from the drilled well closest to the well to be evaluated.

[0020] The degree of curvature development refers to the degree of bending of the strata within a specified range around the design well trajectory direction according to geophysical seismic interpretation when subjected to tectonic stress compression.

[0021] The geological steering reference marker layer refers to the lateral comparability of the natural gamma and double lateral curve characteristics of parameter wells, exploratory wells, and development pilot wells within the comparative section;

[0022] The variation characteristics of logging parameter combinations refer to the lateral comparability of the variation characteristics of lithology, drilling time, gas logging, and elemental logging parameters of parameter wells, exploratory wells, and development pilot wells within the comparative interval.

[0023] The target window height refers to the vertical thickness of the oil and gas-bearing target layer that the horizontal well is required to traverse.

[0024] Preferably, the step of calculating the formation attitude change risk index R of the well to be evaluated is... DCCZ include:

[0025] If the stratigraphic attitude change is ≤5°, then the risk index R for stratigraphic attitude change is... DCCZ =1.0;

[0026] If 5° < stratigraphic attitude change ≤ 10°, then the stratigraphic attitude change risk index R DCCZ =2.0;

[0027] If the stratigraphic attitude change is greater than 10°, the risk index R of the stratigraphic attitude change will be increased. DCCZ =3.0.

[0028] Preferably, the step of calculating the well vibration error risk index R of the well to be evaluated is... JZWC include:

[0029] If the well vibration error is ≤10.0m, then the well vibration error risk index R JZWC =1.0;

[0030] If 10.0m < well vibration error ≤ 30.0m, then the well vibration error risk index R JZWC =2.0;

[0031] If the well vibration error is greater than 30.0m, then the well vibration error risk index R will be increased. JZWC =3.0.

[0032] Preferably, the risk index R for the degree of curvature development of the well to be evaluated is obtained. QLFY include:

[0033] The wells to be evaluated are classified according to the degree of curvature development: blank curvature zone, spotted curvature, and striped curvature.

[0034] If the degree of curvature development is a blank curvature zone, then the risk index R of the degree of curvature development is... QLFY =1.0;

[0035] If the degree of curvature development is speckled curvature, then the risk index R of the degree of curvature development is increased. QLFY =2.0;

[0036] If the degree of curvature development is strip-shaped with relatively high curvature, then the risk index R of the degree of curvature development will be increased. QLFY =3.0.

[0037] Preferably, the step of determining the risk index R of the geological steering reference marker layer of the well to be evaluated is... BZC include:

[0038] If there are ≥8 geological guidance reference marker layers within the comparison section, then the risk index R of the geological guidance reference marker layers will be increased. BZC =1.0;

[0039] If there are 5 or less geological steering reference marker layers within the correlation interval and less than 8, then the risk index R of the geological steering reference marker layer is... BZC =2.0;

[0040] If there are fewer than 5 geological guidance reference marker layers within the comparison section, then the risk index R of the geological guidance reference marker layers will be reduced. BZC =3.0.

[0041] Preferably, the risk index R for obtaining the combination of logging parameters of the well to be evaluated is... LJCS include:

[0042] If the lateral comparability of changes in lithology, drilling time, gas logging data, and elemental logging parameters within the same stratigraphic interval is significant, meaning that two or more parameters are clearly distinguishable, then the characteristic risk index R of the changes in logging parameter combinations is increased. LJCS =1.0;

[0043] If the lateral comparability of changes in lithology, drilling time, gas logging data, and elemental logging parameters within the same stratigraphic interval is moderate, meaning that one parameter shows significant differentiation, then the characteristic risk index R of the changes in logging parameter combinations is... LJCS =2.0;

[0044] If the lateral comparability of changes in lithology, drilling time, gas logging data, and elemental logging parameters within a given interval is poor, meaning no parameters can be clearly distinguished, then the characteristic risk index R of the changes in logging parameter combinations is increased. LJCS =3.0.

[0045] Preferably, the step of determining the target window height risk index R of the well to be evaluated is... BCGD include:

[0046] If the target window height is ≥10.0m, then the target window height risk index R will be increased. BCGD =1.0;

[0047] If 5.0m ≤ target window height < 10.0m, then the target window height risk index R is... BCGD =2.0;

[0048] If the target window height is less than 5.0m, then the target window height risk index R is increased. BCGD =3.0.

[0049] A preferred method for establishing the mathematical model of the multiplier effect comprehensive risk index includes:

[0050] According to formula R ZH1 =η[R DCCZ (R JZWC +R QLFY (R) BZC +R BCGD )+R LJCS Establish a mathematical model for the multiplier effect comprehensive risk index;

[0051] Where η is the matching coefficient;

[0052] The evaluation criteria for the mathematical model of the multiplier effect comprehensive risk index are as follows:

[0053] Category I Low Risk: R ZH1 ≤20; Category II Medium Risk: 20 < R ZH1 ≤30; Category III High Risk: R ZH1 >30.

[0054] A preferred method for establishing the mathematical model of the comprehensive risk index based on grey relational weighting coefficients includes:

[0055] We acquire geophysical and seismic interpretation information and related drilling geological parameters from multiple wells in multiple work areas and different exploration strata. Based on the actual drilling conditions, we comprehensively evaluate and determine the geological steering risk level, which serves as the data for modeling sample analysis.

[0056] The stratigraphic attitude variation R was obtained based on grey relational analysis and normalization. DCCZ Well vibration error R JZWC Curvature development degree R QLFY Geological guidance reference marker layer R BZC Characteristics of changes in logging parameter combinations R LJCS Target window height R BCGD Weighting coefficients;

[0057] According to the formula

[0058] R ZH2 =a*R DCCZ+b*R JZWC +c*R QLFY +d*R BZC +e*R LJCS +f*R BCGD

[0059] A mathematical model for a comprehensive risk index based on grey relational weighting coefficients is established, where a, b, c, d, e, and f are R0, ... and R0, respectively. DCCZ R JZWC R QLFY R BZC R LJCS R BCGD Weighting coefficients;

[0060] The evaluation criteria for the comprehensive risk index mathematical model with grey relational weighting coefficients are as follows:

[0061] Category I Low Risk: R ZH2 ≤1.5; Class II medium risk: 1.5 < R ZH2 ≤1.85; Category III High Risk: R ZH2 >1.85.

[0062] The beneficial effects of this invention are as follows:

[0063] 1. This method, based on geophysical and seismic interpretation and drilling geological risk assessment parameters, outputs the geological steering risk level of the well to be evaluated by combining the evaluation results of a multiplicative effect comprehensive risk index mathematical model and a grey relational weight coefficient comprehensive risk index mathematical model. This method evaluates from both subjective and objective perspectives, comprehensively considering influencing factors. Its scientific and reasonable evaluation method overcomes the limitations of traditional evaluation methods, which are easily restricted by the analyst's understanding of the pre-drilling data and subjective perception of the target well design. It can accurately assess the risks faced during geological steering adjustments during drilling; it facilitates targeted solution techniques for Class II medium-risk and Class III high-risk levels, effectively improving reservoir encounter rate, reducing the risk of geological steering drilling to the target layer, and avoiding complex drilling engineering.

[0064] 2. This method is based on geophysical and seismic interpretation, regional geology and existing well data to establish an integrated well-seismic geological guidance risk assessment. This method is streamlined and quantitative, simple to implement, low in cost and resource consumption, and easy to promote.

[0065] 3. This method has been applied in 118 horizontal wells in the exploration and development of unconventional oil and gas reservoirs. It is applicable to the rapid assessment of geological steering risks in different blocks and strata. In particular, it provides a reliable method for the assessment of geological steering risks in new blocks and new strata, which helps to reduce engineering implementation risks and improve exploration and development results. Attached Figure Description

[0066] Figure 1This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0067] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0068] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0069] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0070] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0071] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0072] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means "two or more."

[0073] Example 1

[0074] Figure 1A preferred embodiment of this application is shown. Figure 1 The diagram shows a flowchart of a well-seismic integrated horizontal well geological steering risk assessment method according to the first embodiment of this application. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0075] Step 1: Obtain geophysical and seismic interpretation information and relevant drilling geological parameters of the well to be evaluated;

[0076] Step 101: Obtain geophysical and seismic interpretation information of the well to be evaluated, including changes in stratigraphic attitude, well-seismic error, and degree of curvature development;

[0077] The stratigraphic attitude variation refers to the maximum variation of the stratigraphic dip angle along the designed trajectory direction of the horizontal segment of the target layer, obtained from geophysical and seismic interpretation.

[0078] The well-seismic error refers to the difference between the depth of the target layer obtained from the drilled well and the depth of the target layer interpreted by geophysical seismic exploration; it is calculated using data obtained from the drilled well closest to the well to be evaluated.

[0079] The curvature development degree refers to the degree of bending of the strata within a 50.0m radius around the design well trajectory direction as interpreted from geophysical seismic data, when the strata are compressed by tectonic stress. It can be interpreted as blank curvature zones, spotted curvature development, striped curvature development, etc.

[0080] Step 102: Obtain relevant drilling geological parameter data for the well to be evaluated, including geological steering reference marker layers, characteristics of changes in logging parameter combinations, and target window height;

[0081] The geological steering reference marker layer refers to the lateral comparability of the natural gamma and dual lateral curve characteristics of vertical wells such as parameter wells, exploratory wells, and development pilot wells within the region in the comparison interval; the comparison interval is generally selected from a vertical thickness of 250.0m above the target layer to a vertical thickness of 20.0m below the target layer.

[0082] The variation characteristics of logging parameter combinations refer to the lateral comparability of the variation characteristics of logging parameter combinations such as lithology, drilling time, gas logging results, and elements in the comparison interval for vertical wells such as parameter wells, exploratory wells, and development pilot wells within the region.

[0083] The target window height refers to the vertical thickness of the oil and gas target layer that the horizontal well is required to penetrate.

[0084] Step 2: Calculate the formation attitude change risk index R of the well to be evaluated. DCCZ Well vibration error risk index R JZWC Curvature development degree risk index R QLFY ;

[0085] Step 201: Calculate the formation attitude change risk index R of the well to be evaluated. DCCZ ;

[0086] For stratigraphic attitude changes ≤5°, the stratigraphic attitude change risk index R is defined. DCCZ =1.0;

[0087] A stratigraphic attitude change risk index R is defined as follows: 5° < stratigraphic attitude change ≤ 10°. DCCZ =2.0;

[0088] When the stratigraphic attitude change is greater than 10°, the stratigraphic attitude change risk index R is defined. DCCZ =3.0;

[0089] Step 202: Calculate the well vibration error risk index R of the well to be evaluated. JZWC

[0090] For well-seismic errors ≤ 10.0m, the well-seismic error risk index R is defined. JZWC =1.0;

[0091] For well-seismic error between 10.0m and 30.0m, the well-seismic error risk index R is defined. JZWC =2.0;

[0092] If the well-seismic error is greater than 30.0m, the well-seismic error risk index R is defined. JZWC =3.0;

[0093] Step 203: Calculate the risk index R of the curvature development degree of the well to be evaluated. QLFY

[0094] The degree of curvature development is defined as the blank curvature zone, and the risk index R for the degree of curvature development is defined. QLFY =1.0;

[0095] The degree of curvature development is defined as speckled curvature with relatively well-developed curvature, and the risk index R for the degree of curvature development is defined. QLFY =2.0;

[0096] The degree of curvature development is defined as strip-shaped curvature with relatively well-developed curvature, and the risk index R for the degree of curvature development is defined. QLFY =3.0;

[0097] Step 3: Calculate the risk index R of the geological steering reference marker layer of the well to be evaluated. BZC Risk index R of changes in logging parameter combinations LJCS Target window height risk index R BCGD ;

[0098] Step 301: Calculate the risk index R of the geological steering reference marker layer of the well to be evaluated. BZC ;

[0099] The stratigraphic interval contains ≥8 geological guidance reference marker layers, indicating strong comparability. A risk index R for these geological guidance reference marker layers is defined. BZC =1.0;

[0100] With 5 to 8 geological guidance reference layers within the correlation interval, the correlation is relatively strong. A risk index R for the geological guidance reference reference layer is defined. BZC =2.0;

[0101] The correlation interval has fewer than 5 geological guidance reference layers, indicating poor correlation. Therefore, a risk index R for the geological guidance reference layer is defined. BZC =3.0;

[0102] Step 302: Calculate the risk index R of the variation characteristics of the logging parameter combination of the well to be evaluated. LJCS ;

[0103] The lateral comparability of changes in logging parameters such as lithology, drilling time, gas logging, and elements within the same formation is significant. Two or more parameters show clear distinction. A characteristic risk index R for changes in logging parameter combinations is defined. LJCS =1.0;

[0104] The lateral comparability of changes in logging parameters such as lithology, drilling time, gas logging, and elements within the same formation is moderate. One parameter shows significant differentiation. A characteristic risk index R for changes in logging parameter combinations is defined. LJCS =2.0;

[0105] The lateral comparability of changes in logging parameters such as lithology, drilling time, gas logging, and elements within the same formation is poor, with no parameters clearly distinguishable. Therefore, a risk index R representing the characteristics of changes in logging parameter combinations is defined. LJCS =3.0;

[0106] Step 303: Calculate the target window height risk index R of the well to be evaluated. BCGD ;

[0107] For a target window height ≥ 10.0m, the target window height risk index R is defined. BCGD =1.0;

[0108] For a target window height of 5.0m ≤ target window height < 10.0m, the target window height risk index R is defined. BCGD =2.0;

[0109] If the target window height is less than 5.0m, the target window height risk index R is defined. BCGD =3.0;

[0110] Step 4: Establish a mathematical model and evaluation criteria for the integrated well-seismic risk index;

[0111] Step 401, construct a mathematical model for the multiplier effect comprehensive risk index:

[0112] R ZH1 =η[R DCCZ (R JZWC +R QLFY (R) BZC +R BCGD )+R LJCS ]

[0113] In the formula, η is the matching coefficient, which is dimensionless and ranges from 1.0 to 2.0, with 1.58 for the Sichuan Basin.

[0114] Risk level classification standard, Category I low risk: R ZH1 ≤20; Category II Medium Risk: 20 < R ZH1 ≤30; Category III High Risk: R ZH1 >30.

[0115] Step 402: Construct a mathematical model for the comprehensive risk index of grey relational weight coefficients;

[0116] Geophysical and seismic interpretation information and related drilling geological parameters of 12 drilled wells in 6 different exploration strata in 7 work areas were obtained. Based on the actual drilling conditions, the geological steering risk level was determined by authoritative experts and used as the modeling sample data. The risk index values ​​of the single evaluation parameters of the selected drilled well sample data all included levels 1-3 (see Table 1).

[0117] Table 1 Sample Data for Integrated Well-Seismic Risk Assessment and Analysis of Drilled Wells

[0118]

[0119]

[0120] A 6×12 correlation matrix X′ was established, consisting of six risk indices from geophysical and seismic interpretation and drilling geology of 12 drilled wells, where X... ij For the i-th individual risk index, the data value of the j-th drilled well;

[0121]

[0122] According to the formula Dimensionless processing was performed on the sample data of geophysical and seismic interpretation and drilling geological parameter risk level analysis of 12 drilled wells to obtain the initial valued correlation matrix X;

[0123]

[0124] Based on the actual drilling conditions and comprehensive evaluation by authoritative experts, the geological steering risk level of 12 drilled wells was determined as a reference series X0′=(1.0, 1.0, 3.0, 2.0, 3.0, 3.0, 1.0, 2.0, 2.0, 3.0, 2.0, 3.0). After dimensionless processing of the reference series, we get: X0=(0.333, 0.333, 1.000, 0.667, 1.000, 1.000, 0.333, 0.667, 0.667, 1.000, 0.667, 1.000).

[0125] According to the formula Δ=|X0-X i | Calculate the absolute difference between the reference series and the initialized correlation matrix X for each individual risk index to obtain the absolute value difference matrix Δ.

[0126]

[0127] From the absolute value difference matrix Δ, we obtain Δmin = 0 and Δmax = 0.667, where Δmin is the minimum difference between the two extremes and Δmax is the maximum difference between the two extremes.

[0128] The correlation ξ(i) between the six evaluation parameters of the drilled well geophysical and seismic interpretation and drilling geology and the geological steering risk level determined by authoritative experts based on the actual drilling conditions is calculated using the following formula:

[0129]

[0130] In the formula, ξ(i) represents the correlation degree of the i-th risk assessment parameter of the drilled well;

[0131] m represents the number of wells analyzed in the drilled well sample;

[0132] Δmin is the minimum difference between the two poles; Δmax is the maximum difference between the two poles.

[0133] Δ(k) is the absolute difference between the reference sequence and the sequence of the initialized correlation matrix;

[0134] The risk assessment parameter R is calculated based on the stratigraphic attitude variation. DCCZ Well vibration error R JZWC Curvature development degree R QLFY Geological guidance reference marker layer R BZC Characteristics of changes in logging parameter combinations R LJCS Target window height R BCGD The correlation coefficients were 0.875, 0.652, 0.583, 0.639, 0.625, and 0.673, respectively.

[0135] The correlation degree of each parameter is normalized, and the calculation formula is as follows:

[0136]

[0137] In the formula, αi is the weight coefficient of the i-th parameter;

[0138] Normalization processing yields the risk assessment parameter stratigraphic attitude variation R. DCCZ Well vibration error R JZWC Curvature development degree R QLFY Geological guidance reference marker layer R BZC Characteristics of changes in logging parameter combinations R LJCS Target window height R BCGD The weighting coefficients are 0.22, 0.16, 0.14, 0.16, 0.15, and 0.17.

[0139] Mathematical model of comprehensive risk index with grey relational weight coefficients:

[0140] R ZH2 =0.22R DCCZ +0.16R JZWC +0.14R QLFY +0.16R BZC +0.15R LJCS +0.17R BCGD

[0141] Risk level classification standard: Category I is low risk: R ZH2 ≤1.5; Category II is medium risk: 1.5 < R ZH2 ≤1.85; Category III is high risk: R ZH2 >1.85.

[0142] Step 5: Analyze the results of the mathematical model of comprehensive risk index combining the multiplier effect and the grey relational weighting coefficient to output the geological steering risk level of the well to be evaluated.

[0143] The evaluation conclusions of both comprehensive risk index mathematical models are classified as Class I low risk, according to the Class I low risk interpretation method.

[0144] The interpretation method for Category II medium risk is divided into three cases: first, one of the evaluation conclusions of the two comprehensive risk index mathematical models is Category I low risk and the other evaluation conclusion is Category II medium risk; second, both evaluation conclusions of the two comprehensive risk index mathematical models are Category II medium risk; and third, one of the evaluation conclusions of the two comprehensive risk index mathematical models is Category I low risk and the other evaluation conclusion is Category III high risk.

[0145] The interpretation of Category III high risk can be divided into two cases: one is that both comprehensive risk index mathematical models are Category III high risk, and the other is that one of the evaluation conclusions of the two comprehensive risk index mathematical models is Category II medium risk and the other evaluation conclusion is Category III high risk.

[0146] For Class II medium-risk and Class III high-risk areas, targeted solution technologies should be adopted to effectively improve the reservoir drilling rate, reduce the risk of drilling to the target layer by geological steering, avoid the risks of complex drilling engineering, and improve the exploration and development effect.

[0147] This invention was applied to Well A, a new horizontal well in the HX block of the Sichuan Basin, targeting the Maokou Formation. Geophysical and seismic interpretation information and relevant drilling geological parameters were obtained. The risk index corresponding to six evaluation parameters—formation attitude variation, well-seismic error, curvature development, geological steering reference layer, logging parameter combination variation characteristics, and target window height—was calculated. DCCZ =2.0, R JZWC =1.0, R QLFY =2.0, R BZC =1.0, R LJCS =1.0, R BCGD =2.0, calculated based on the integrated well and seismic risk index mathematical model. ZH1 =22.1, R ZH2 =1.53. Both mathematical model evaluation standards show that it is a Class II medium risk. It is proposed to adopt refined geological modeling and near-bit steerable tool drilling. Compared with the previous qualitative analysis that the drilling risk of new strata in this block is relatively high and rotary steerable tool drilling is appropriate, the implementation of the technical solution has achieved a high-quality target of 93.6% horizontal well target layer drilling rate and smooth wellbore trajectory control, saving drilling costs of 950,000 yuan, and realizing a win-win model of geological + engineering + investment cost reduction.

[0148] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0149] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0150] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0151] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as it is used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0152] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for geological steering risk assessment of horizontal wells integrating well and seismic testing, characterized in that, Includes the following steps: Obtain geophysical and seismic interpretation information and relevant drilling geological parameters of the well to be evaluated; Calculate the formation attitude change risk index R of the well to be evaluated DCCZ Well vibration error risk index R JZWC Curvature development degree risk index R QLFY ; Determine the risk index R of the geological steering reference marker layer of the well to be evaluated. BZC Risk index R of changes in logging parameter combinations LJCS Target window height risk index R BCGD ; A mathematical model and evaluation standard for an integrated well-seismic risk index are established. The mathematical model includes a multiplicative effect integrated risk index mathematical model and a grey relational weight coefficient integrated risk index mathematical model. The evaluation results of the comprehensive risk index mathematical model combining the multiplier effect and the comprehensive risk index mathematical model with the grey relational weight coefficient are used to output the geological steering risk level of the well to be evaluated. If both mathematical models conclude that the risk level is Class I low risk, then the output risk level will be Class I low risk. If either of the evaluation conclusions of the two mathematical models is Class I low risk and the other is Class II medium risk, or if both of the evaluation conclusions of the two mathematical models are Class II medium risk, or if either of the evaluation conclusions of the two mathematical models is Class I low risk and the other is Class III high risk, then the output risk level is Class II medium risk. If the evaluation conclusions of both mathematical models are Class III high risk, or if one of the evaluation conclusions of the two mathematical models is Class II medium risk and the other is Class III high risk, then the output risk level is Class III high risk. The method for establishing the mathematical model of the multiplier effect comprehensive risk index includes: According to the formula Establish a mathematical model for the multiplier effect comprehensive risk index; in, The matching coefficient; The evaluation criteria for the mathematical model of the multiplier effect comprehensive risk index are as follows: Category I Low Risk: ≤20; Category II Medium Risk: 20 < ≤30; Category III High Risk: >

30.

2. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The acquisition of geophysical and seismic interpretation information and related drilling geological parameters of the well to be evaluated includes: Obtain geophysical and seismic interpretation information of the well to be evaluated, including changes in stratigraphic attitude, well-seismic error, and degree of curvature development; Obtain relevant drilling geological parameter data for the well to be evaluated, including geological steering reference marker layers, characteristics of changes in logging parameter combinations, and target window height; The stratigraphic attitude variation refers to the maximum variation of the stratigraphic dip angle along the designed trajectory direction of the horizontal segment of the target layer, obtained from geophysical and seismic interpretation. The well seismic error refers to the difference between the target layer depth obtained from the drilled well and the target layer depth interpreted by geophysical seismic exploration. It is calculated using data obtained from the drilled well closest to the well to be evaluated. The degree of curvature development refers to the degree of bending of the strata within a specified range around the design well trajectory direction according to geophysical seismic interpretation when subjected to tectonic stress compression. The geological steering reference marker layer refers to the lateral comparability of the natural gamma and double lateral curve characteristics of parameter wells, exploratory wells, and development pilot wells within the comparative section; The variation characteristics of logging parameter combinations refer to the lateral comparability of the variation characteristics of lithology, drilling time, gas logging, and elemental logging parameters of parameter wells, exploratory wells, and development pilot wells within the comparative interval. The target window height refers to the vertical thickness of the oil and gas-bearing target layer that the horizontal well is required to traverse.

3. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The risk index R of formation attitude change in the well to be evaluated is obtained. DCCZ include: If the stratigraphic attitude change is ≤5°, then the risk index R for stratigraphic attitude change is... DCCZ =1.0; If 5° < stratigraphic attitude change ≤ 10°, then the stratigraphic attitude change risk index R DCCZ =2.0; If the stratigraphic attitude change is greater than 10°, the risk index R of the stratigraphic attitude change will be increased. DCCZ =3.

0.

4. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The method for determining the well vibration error risk index R of the well to be evaluated JZWC include: If the well vibration error is ≤10.0m, then the well vibration error risk index R JZWC =1.0; If 10.0m < well vibration error ≤ 30.0m, then the well vibration error risk index R JZWC =2.0; If the well vibration error is greater than 30.0m, then the well vibration error risk index R will be increased. JZWC =3.

0.

5. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The risk index R for the degree of curvature development of the well to be evaluated is obtained. QLFY include: The wells to be evaluated are classified according to the degree of curvature development: blank curvature zone, spotted curvature, and striped curvature. If the degree of curvature development is a blank curvature zone, then the risk index R of the degree of curvature development is... QLFY =1.0; If the degree of curvature development is speckled curvature, then the risk index R of the degree of curvature development is increased. QLFY =2.0; If the degree of curvature development is strip-shaped with relatively high curvature, then the risk index R of the degree of curvature development will be increased. QLFY =3.

0.

6. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The risk index R of the geological steering reference marker layer of the well to be evaluated is obtained. BZC include: If there are ≥8 geological guidance reference marker layers within the comparison section, then the risk index R of the geological guidance reference marker layers will be increased. BZC =1.0; If there are 5 or less geological steering reference marker layers within the correlation interval and less than 8, then the risk index R of the geological steering reference marker layer is... BZC =2.0; If there are fewer than 5 geological guidance reference marker layers within the comparison section, then the risk index R of the geological guidance reference marker layers will be reduced. BZC =3.

0.

7. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The risk index R for the variation characteristics of the logging parameter combination of the well to be evaluated is obtained. LJCS include: If the lateral comparability of changes in lithology, drilling time, gas logging data, and elemental logging parameters within the same stratigraphic interval is significant, meaning that two or more parameters are clearly distinguishable, then the characteristic risk index R of the changes in logging parameter combinations is increased. LJCS =1.0; If the lateral comparability of changes in lithology, drilling time, gas logging data, and elemental logging parameters within the same stratigraphic interval is moderate, meaning that one parameter shows significant differentiation, then the characteristic risk index R of the changes in logging parameter combinations is... LJCS =2.0; If the lateral comparability of changes in lithology, drilling time, gas logging data, and elemental logging parameters within a given interval is poor, meaning no parameters can be clearly distinguished, then the characteristic risk index R of the changes in logging parameter combinations is increased. LJCS =3.

0.

8. The integrated well-seismic risk assessment method for horizontal wells, as described in claim 1, is characterized in that... The risk index R for the height of the target window of the well to be evaluated is obtained. BCGD include: If the target window height is ≥10.0m, then the target window height risk index R will be increased. BCGD =1.0; If 5.0m ≤ target window height < 10.0m, then the target window height risk index R is... BCGD =2.0; If the target window height is less than 5.0m, then the target window height risk index R is increased. BCGD =3.

0.

9. The integrated well-seismic risk assessment method for horizontal wells as described in claim 1, characterized in that, The method for establishing the mathematical model of the comprehensive risk index with grey relational weight coefficients includes: We acquire geophysical and seismic interpretation information and related drilling geological parameters from multiple wells in multiple work areas and different exploration strata. Based on the actual drilling conditions, we comprehensively evaluate and determine the geological steering risk level, which serves as the data for modeling sample analysis. The stratigraphic attitude variation R was obtained based on grey relational analysis and normalization. DCCZ Well vibration error R JZWC Curvature development degree R QLFY Geological guidance reference marker layer R BZC Characteristics of changes in logging parameter combinations R LJCS Target window height R BCGD Weighting coefficients; According to the formula A mathematical model for a comprehensive risk index based on grey relational weighting coefficients is established, where a, b, c, d, e, and f are R0, ... and R0, respectively. DCCZ R JZWC R QLFY R BZC R LJCS R BCGD Weighting coefficients; The evaluation criteria for the comprehensive risk index mathematical model with grey relational weighting coefficients are as follows: Category I Low Risk: ≤1.5; Category II Medium Risk: 1.5 < ≤1.85; Category III High Risk: >1.85.

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