Well drilling geological engineering risk early warning method based on well-seismic integrated parameters

Abstract

The invention provides a drilling geological engineering risk early warning method based on well-seismic integrated parameters, and the method comprises the steps: obtaining the abnormal main control factors of an easy-to-collapse and easy-to-leak section based on the drilling characteristics, logging characteristics and logging characteristics of the easy-to-collapse and easy-to-leak section; performing full-strata lithology prediction on the to-be-drilled well to obtain the distribution conditions of mudstone, sandstone and coal seam; according to the distribution conditions of the mudstone, the sandstone and the coal seam, abnormal main control factors corresponding to the lithology are predicted; performing full-strata velocity inversion on the to-be-drilled well, and predicting an elastic parameter; according to the prediction condition of the elastic parameters, predicting the formation pressure, collapse pressure, leakage pressure and fracture pressure of the to-be-drilled well; and constructing a risk prediction model by integrating the prediction conditions of the pore pressure, the collapse pressure, the leakage pressure and the fracture pressure of the full strata of the to-be-drilled well and the prediction conditions of the abnormal main control factors corresponding to the lithology. The method achieves the timely recognition of exploration risks, improves the operation efficiency, and guarantees the operation safety.

Description

Technical Field

[0001] This invention belongs to the field of drilling technology and relates to a drilling geological engineering risk early warning method based on integrated well and seismic parameters. Background Technology

[0002] With the deepening of exploration wells in the East China Sea in recent years, the exploration risks such as well leakage and overflow caused by shallow formation instability, deep coal seam development, and high formation pressure have been increasing year by year. This has become a prominent problem that the company urgently needs to solve in order to ensure safe production and reduce costs and increase efficiency. Therefore, it is very urgent and necessary to combine well-seismic integrated data analysis technology to conduct pre-drilling risk assessment and prediction research on shallow unstable strata and deep coal seam development.

[0003] Existing technologies for integrated well-seismic geological steering risk assessment in horizontal wells rely on high-precision geophysical and seismic interpretation information and drilling geological parameters. Significant interpretation errors (such as misjudgment of formation attitude) can lead to inaccurate model assessments. A more realistic conclusion can only be reached through multi-parameter (six risk indices) fusion and parallel computation of two models, which places high demands on computing power and real-time performance, potentially impacting on-site decision-making efficiency. Furthermore, the lack of support for real-time data updates (such as dynamic feedback from logging-while-drilling data) prevents real-time tracking of geological steering risks through updates to drilling data and formation information, failing to meet the timeliness requirements of on-site operations. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides a drilling geological engineering risk early warning method based on integrated well and seismic parameters. This method enables timely identification of exploration risks, improves operational efficiency, and thus ensures operational safety.

[0005] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0006] This invention provides a drilling geological engineering risk early warning method based on integrated well and seismic parameters, the early warning method comprising:

[0007] Based on the drilling, logging, and well logging characteristics of easily collapsed and leaking sections, the main anomaly controlling factors of these sections are obtained.

[0008] Perform full-stratum lithological prediction on the well to be drilled to obtain the distribution of mudstone, sandstone and coal seams;

[0009] Based on the distribution of mudstone, sandstone and coal seams, the main anomaly controlling factors corresponding to each lithology are predicted;

[0010] The entire formation velocity is inverted for the well to be drilled, and the elastic parameters are predicted.

[0011] Based on the predicted elastic parameters, the formation pressure, collapse pressure, leakage pressure, and fracture pressure of the well to be drilled are predicted.

[0012] A risk prediction model is constructed by combining the predicted pore pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation of the well to be drilled with the predicted anomaly control factors corresponding to each lithology.

[0013] As a preferred technical solution of the present invention, the section prone to collapse and leakage includes the area where at least one of the following abnormal conditions occurs: wellbore collapse, blockage, stuck drill bit, reaming, enlargement, well leakage, gas intrusion, and abnormal drilling speed.

[0014] As a preferred technical solution of the present invention, the distribution of mudstone is predicted by well stacking seismic profile inversion.

[0015] As a preferred technical solution of the present invention, the distribution of sandstone is predicted by well stacking seismic profile inversion.

[0016] As a preferred technical solution of the present invention, the main controlling factors of shale anomalies are predicted based on well logging data and well-seismic joint inversion.

[0017] As a preferred technical solution of the present invention, the main controlling factors of sandstone anomalies are predicted based on well logging data, seismic data and post-stack seismic inversion.

[0018] As a preferred technical solution of the present invention, the main controlling factors of coal seam anomalies are predicted based on well logging data and post-stack seismic properties.

[0019] As a preferred technical solution of the present invention, the early warning method further includes determining the pressurization well section based on the distribution of mudstone, sandstone and coal seam, and predicting the formation pressure.

[0020] As a preferred technical solution of the present invention, based on the predicted formation pressure and the predicted elastic parameters, the formation pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation system to be drilled are predicted.

[0021] As a preferred technical solution of the present invention, a risk prediction model is constructed by applying the comprehensive index method to integrate the prediction of pore pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation of the well to be drilled and the prediction of the main abnormal control factors corresponding to each lithology.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] (1) This invention provides a drilling geological engineering risk early warning method based on integrated well and seismic parameters. This method enables timely identification of exploration risks, improves operational efficiency, and thus ensures operational safety.

[0024] (2) This invention provides a drilling geological engineering risk early warning method based on well-seismic integrated parameters. Compared with traditional methods, the core advantages of this method are its multi-dimensional data integration capability, dynamic modeling accuracy and whole-process active prevention and control mechanism.

[0025] (3) This invention provides a drilling geological engineering risk early warning method based on well-seismic integrated parameters. This method solves the problems of poor adaptability of traditional technology to complex geological conditions and delayed early warning. It also provides key technical support for the efficient development of deep and ultra-deep oil and gas resources. Attached Figure Description

[0026] Figure 1a This is a predicted diagram of the mud-rich section in the upper part of the Huagang Formation of a well to be drilled in Example 1.

[0027] Figure 1b This is a predicted diagram of the mud-rich section in the upper part of the Huagang Formation of a well to be drilled in Example 1.

[0028] Figure 1c This is a predicted mud-rich section of the lower part of the Huagang Formation in Example 1.

[0029] Figure 1d This is a predicted image of the mud-rich section of the Pinghu Formation in Example 1, which is to be drilled.

[0030] Figure 2 The image shows the inversion prediction of the lithological profile (right image) from the back-stack seismic profile (left image) of a well to be drilled in Example 1.

[0031] Figure 3 This is an inversion profile of the clay content of a well to be drilled in Example 1.

[0032] Figure 4 This is a porosity inversion profile of a well to be drilled in Example 1.

[0033] Figure 5 The image shows the inversion prediction of the lithological profile (right image) from the back-stack seismic profile (left image) of a well to be drilled in Example 1.

[0034] Figure 6 This is a cross-sectional view of a fracture prediction for a well to be drilled in Example 1.

[0035] Figure 7 This is a prediction of pre-drilling pore pressure (pressurization section) for a well to be drilled in Example 1.

[0036] Figure 8 This is a predicted profile of the "four pressures" of a well to be drilled in Example 1.

[0037] Figure 9 This is a profile of a well to be drilled in Example 1, based on the "four pressures" + inversion + lithology prediction of the whole formation inversion.

[0038] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0039] The technical solution of this application will be further described below through specific implementation methods.

[0040] This invention provides a drilling geological engineering risk early warning method based on integrated well and seismic parameters, the early warning method comprising:

[0041] Based on the drilling, logging, and well logging characteristics of easily collapsed and leaking sections, the main anomaly controlling factors of these sections are obtained.

[0042] Perform full-stratum lithological prediction on the well to be drilled to obtain the distribution of mudstone, sandstone and coal seams;

[0043] Based on the distribution of mudstone, sandstone and coal seams, the main anomaly controlling factors corresponding to each lithology are predicted;

[0044] The entire formation velocity is inverted for the well to be drilled, and the elastic parameters are predicted.

[0045] Based on the predicted elastic parameters, the formation pressure, collapse pressure, leakage pressure, and fracture pressure of the well to be drilled are predicted.

[0046] A risk prediction model is constructed by combining the predicted pore pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation of the well to be drilled with the predicted anomaly control factors corresponding to each lithology.

[0047] In one specific embodiment of the present invention, the section prone to collapse and leakage includes an area where at least one of the following abnormal conditions occurs: wellbore collapse, blockage, stuck drill bit, reaming, enlargement, well leakage, gas intrusion, and abnormal drilling rate.

[0048] In one specific embodiment of the present invention, based on the specific location where the above-mentioned anomaly occurs, combined with the lithological characteristics of that location, and through comprehensive analysis of the seismic response characteristics and seismic attributes of the area, the main controlling factors of the anomaly are selected.

[0049] In one specific embodiment of the present invention, the distribution of mudstone is predicted by well stacking seismic profile inversion.

[0050] In one specific embodiment of the present invention, based on seismic data (post-stack data) and well logging data, and after well-seismic calibration, the distribution of mudstone is obtained through deterministic impedance inversion.

[0051] In one specific embodiment of the present invention, the distribution of sandstone is predicted by well stacking seismic profile inversion.

[0052] In one specific embodiment of the present invention, the distribution of sandstone can be obtained by deterministic impedance spectroscopy based on seismic data (post-stack data) and well logging data, and by performing well-seismic calibration.

[0053] In one specific embodiment of the present invention, the distribution of sandstone can also be obtained by inverting elastic parameters based on seismic data (pre-stack data) and well logging data, and by performing well-seismic calibration.

[0054] In one specific embodiment of the present invention, the main controlling factors of shale anomalies are predicted based on well logging data and well-seismic joint inversion.

[0055] In one specific embodiment of the present invention, gamma indicator curves can be obtained from well logging data, and clay distribution can be obtained using direct well logging interpretation methods, such as the GR index method. Alternatively, the relationship between wave impedance and clay content can be obtained through well-seismic combined inversion to determine clay distribution.

[0056] In one specific embodiment of the present invention, the main controlling factors of sandstone anomalies are predicted based on well logging data, seismic data, and post-stack seismic inversion.

[0057] In one specific embodiment of the present invention, direct well logging interpretation can be performed using well logging data, such as calculations based on density porosity formulas or integrated porosity models. Alternatively, well logging data and seismic data can be used to perform joint well-seismic inversion to obtain the relationship between wave impedance and porosity, and to obtain the porosity distribution.

[0058] In one specific embodiment of the present invention, the main controlling factors of coal seam anomalies are predicted based on well logging data and post-stack seismic properties.

[0059] In one specific embodiment of the present invention, the predicted distribution of coal seam fractures can be obtained based on well logging data and seismic data by generating fracture probability problems or modeling three-dimensional fracture networks.

[0060] In one specific embodiment of the present invention, the early warning method further includes determining the pressurization well section based on the distribution of mudstone, sandstone and coal seam, and predicting the formation pressure.

[0061] In one specific embodiment of the present invention, based on the predicted formation pressure and the predicted elastic parameters, the formation pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation system to be drilled are predicted.

[0062] In one specific embodiment of the present invention, formation pressure can be predicted based on well logging data analysis methods, such as sonic transit time method and seismic velocity inversion method.

[0063] In one specific embodiment of the present invention, collapse pressure can be predicted using methods such as the Hubbert & Willis formula, the Matthews & Kelly method, the Eaton method, and well logging and geostress inversion.

[0064] In one specific embodiment of the present invention, the critical collapse pressure formula based on the Mohr-Coulomb criterion can be used, or the collapse pressure can be calculated by substituting well logging curves such as density, sonic logging, and gamma logging into the McNally formula.

[0065] In one specific embodiment of the present invention, the leakage pressure can be calculated based on the fact that the leakage pressure is lower than the theoretical rupture pressure when a natural fracture develops: LCP = FP - ΔPLCP = FP - ΔP (ΔP is the pressure drop at the fracture opening, which depends on the fracture density and direction).

[0066] In one specific embodiment of the present invention, a risk prediction model is constructed by applying the comprehensive index method to integrate the predicted pore pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation of the well to be drilled and the predicted abnormal main controlling factors corresponding to each lithology.

[0067] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0068] Example 1

[0069] This embodiment provides a drilling geological engineering risk early warning method for integrated well and seismic parameters, the early warning method including:

[0070] Taking a certain well to be drilled in the East China Sea as an example

[0071] 1. Prediction of rich mud content in the entire well section before drilling of a certain well.

[0072] The prediction results of the mud-rich section of a certain well to be drilled are as follows: Figures 1a to 1d As shown, the upper part of the Longjing Formation consists of gray and brown mudstone interbedded with light gray silty sandstone, siltstone, grayish-white fine sandstone, and argillaceous fine sandstone; the upper part of the upper section of the Huagang Formation consists of gray-brown, brownish-gray, and grayish-brown mudstone, silty mudstone, and light gray and grayish-white siltstone and fine sandstone interbedded with gray silty-gray siltstone; the middle and lower parts of the lower section of the Huagang Formation consist of grayish-white coarse sandstone, medium sandstone, and conglomerate, light gray and grayish-white fine sandstone, siltstone, and silty-gray siltstone interbedded with gray, brown, and grayish-brown mudstone; the lower part of the Pinghu Formation is mainly composed of gray and brownish-gray mudstone.

[0073] Six sets of predictions were made for the mud-rich sections of the Longjing Formation, achieving a 100% prediction rate, with an average thickness accuracy of 80%. Eleven sets of predictions were made for the mud-rich sections of the Huagang Formation, achieving a 72% prediction rate, with an average thickness accuracy of 71%. See details... Figure 2 The inversion profile of a certain well to be drilled is shown in Figure 1, and the statistical table of mudstone from the Huagang Formation of that well is shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] Pre-drilling engineering anomaly warning based on rock clay content: Upper mudstone is prone to fracturing; encountering lithological interfaces may cause obstruction. (See...) Figure 3 The clay content inversion profile shown indicates that, on a certain well to be drilled, the Longjing Formation is predicted to have 6 mudstone sections with a clay content accuracy rate of 84%; the Huagang Formation is predicted to have 11 mudstone sections with a clay content accuracy rate of 81%.

[0078] Pre-drilling engineering anomaly warning based on rock porosity: high-porosity and high-permeability formations are prone to mud cake formation, which may lead to anomalies such as stuck drill bit or obstruction. Figure 4 The porosity inversion profile of a well to be drilled is shown in Table 2. Statistics show that the porosity accuracy of the five sets of high-porosity sandstones in the Longjing Formation is 82%. Statistics of the 12 sets of interbedded sandstone and mudstone in the Huagang Formation show a porosity accuracy of 80%. Specific statistical values ​​are shown in Table 2.

[0079] Table 2

[0080]

[0081]

[0082] 2. Prediction of rich coal-bearing sections in the Pinghu Formation before drilling a certain well.

[0083] The prediction for a deep, flat, coal-rich section of a well to be drilled was 6 sets; 8 sets actually developed, a prediction rate of 75%. The coal seam probability (ratio of cumulative coal seam thickness to formation thickness) was calculated based on a 20m sliding window thickness, and the probability error was less than 30%. See... Figure 5 The inversion profiles of sandstone, mudstone, and coal seams of a certain well to be drilled are shown in Figure 3, and the statistical table of the prediction accuracy rate of the Pinghu Formation coal seam of this well is shown in Table 3.

[0084] Table 3

[0085]

[0086] 3. Prediction of small fractures and fissures in a pre-drilling section of a well to be drilled

[0087] Wellbore collapse and obstruction are prone to occur in fault-developed areas and triangular zones controlled by fault combinations. Figure 6 The well shown has well-developed micro-fractures near the Huagang Formation, which may cause anomalies such as block falling and stuck drill bit; the deep Pinghu Formation has no well-developed fractures.

[0088] 4. Pre-drilling prediction of four pressures and wellbore stability analysis for a well to be drilled

[0089] The formation pressurization characteristics in this area are mainly influenced by secondary hydrocarbon migration. The formation gradually pressurizes from near hydrocarbon unit P4a, above which the formation maintains hydrostatic pressure. Due to the interbedded sandstone and mudstone, and the favorable physical properties of the sandstone, trapped hydrocarbons, leading to increased pressure, the overall pressure coefficient shows a gradual increasing trend. Normal pressure is predicted above 4595m, followed by pressurization. The pressure at 4943m is close to 1.4, consistent with measured data. A mud ratio of 1.45 is recommended for drilling. See details... Figure 7 As shown in Table 4.

[0090] Table 4

[0091] depth Predicted pressure coefficient Measured pressure coefficient Compliance rate 4459.40 1.00 1.002 99％ 4479.30 1.00 0.993 99％ 4482.81 1.00 0.993 99％ 4486.12 1.00 0.993 99％ 4595.01 1.00 0.992 99％ 4943.38 1.39 1.446 96％ 4946.61 1.41 1.445 97％

[0092] Due to mechanical differences and coal seam cleavage characteristics, the leakage pressure and collapse pressure in coal-rich sections differ significantly from those in sandstone and mudstone formations. Coal-rich sections are prone to leakage; simulation results show that the leakage pressure is approximately 0.21 SG lower than that in normal sandstone and mudstone sections. However, due to lower mechanical strength and softer rock, simulation results show that the leakage pressure in coal-rich sections is approximately 0.15 SG higher than that in sandstone and mudstone sections. Based on the predicted collapse and leakage pressures, the mud density is designed according to the following principles: the lower limit of the mud density is higher than the collapse pressure and formation pressure, and the upper limit of the mud density is higher than but lower than the leakage pressure. For the first well section, a mud density of 1.03 (seawater specific gravity) is recommended; for the second well section, a mud density of 1.03 (seawater specific gravity) is recommended; for the third well section, a mud density of 1.03 SG is recommended to begin drilling, gradually increasing the mud density until completion at 1.35 SG; for the fourth well section, a mud density of 1.35 SG is recommended to begin drilling, gradually increasing the mud density until completion at 1.60 SG. For specific data, please refer to Table 5, which provides pressure prediction and mud density recommendations.

[0093] Table 5

[0094]

[0095] In intact formations (without well-developed natural fractures), the leakage pressure is slightly lower than the fracture pressure. However, due to the influence of regional stress state and rock mechanics parameters, the difference varies greatly across different regions. Based on the drilling summary of a neighboring well (NB19-6E-1d), the fracture pressure tested in the fourth section was 1.88SG, and the leakage pressure was 1.85SG. Therefore, it is inferred that the difference between the leakage pressure and the fracture pressure in this well (in intact formation) is 0.03SG. See Figure 8 The image shows a predicted profile of the "four pressures" of a well to be drilled.

[0096] 5. Research on the Classification and Early Warning of Abnormal Risks in the Pre-Drilling Engineering of a Well to be Drilled

[0097] A risk level classification was conducted for a certain well to be drilled, which guided the design and construction of exploratory well operations, improving operational safety and efficiency. (See attached document) Figure 9 As shown.

[0098] Using a comprehensive index for engineering early warning, no high-risk areas were identified under oil-based drilling mud conditions. One medium-risk area was identified in the Longjing Formation, and four medium-risk areas were identified in the Huagang Formation. In actual drilling, drilling fluid with a specific gravity higher than the collapse pressure and wall-stabilizing agents were used at the medium-risk areas to improve operational safety and drilling efficiency. Specific data are shown in Tables 6 to 9.

[0099] Table 6

[0100]

[0101]

[0102] Table 7

[0103]

[0104] Table 8

[0105]

[0106]

[0107] Table 9

[0108]

[0109] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0110] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0111] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0112] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A drilling geological engineering risk early warning method based on integrated well and seismic parameters, characterized in that, The method includes: Based on the drilling, logging, and well logging characteristics of easily collapsed and leaking sections, the main anomaly controlling factors of these sections are obtained. Perform full-stratum lithological prediction on the well to be drilled to obtain the distribution of mudstone, sandstone and coal seams; Based on the distribution of mudstone, sandstone and coal seams, the main anomaly controlling factors corresponding to each lithology are predicted; The entire formation velocity is inverted for the well to be drilled, and the elastic parameters are predicted. Based on the predicted elastic parameters, the formation pressure, collapse pressure, leakage pressure, and fracture pressure of the well to be drilled are predicted. A risk prediction model is constructed by combining the predicted pore pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation of the well to be drilled with the predicted anomaly control factors corresponding to each lithology.

2. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, The vulnerable and leaky sections include areas where at least one of the following abnormal conditions occurs: wellbore collapse, blockage, stuck drill bit, reaming, enlargement, well leakage, gas intrusion, and abnormal drilling rate.

3. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, The distribution of mudstone was predicted by well stacking seismic profile inversion.

4. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, The distribution of sandstone was predicted by well stacking seismic profile inversion.

5. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, The main controlling factors of mudstone anomalies are predicted based on well logging data and combined well-seismic inversion.

6. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, The main controlling factors of sandstone anomalies are predicted based on well logging data, seismic data, and post-stack seismic inversion.

7. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, Predict the main controlling factors of coal seam anomalies based on well logging data and post-stack seismic properties.

8. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 1, characterized in that, The early warning method also includes determining the pressurization well section based on the distribution of mudstone, sandstone and coal seams, and predicting the formation pressure.

9. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 7, characterized in that, Based on the predicted formation pressure and the predicted elastic parameters, the formation pressure, collapse pressure, leakage pressure and fracture pressure of the entire formation system to be drilled are predicted.

10. The drilling geological engineering risk early warning method based on integrated well and seismic parameters according to claim 7, characterized in that, A risk prediction model was constructed by combining the predictions of pore pressure, collapse pressure, leakage pressure, and fracture pressure of the entire formation in the well to be drilled with the predictions of the main anomalies corresponding to each lithology using the comprehensive index method.

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