Geological information forecasting method for advanced drilling under complex karst geological conditions

Abstract

The invention provides a geological information forecasting method for advanced drilling under a complex karst geological condition, and the method comprises the steps: collecting drilling data in real time in an advanced drilling process, and obtaining a rock core sample, the drilling data comprising a drilling speed and a drilling rock core recovery rate; measuring the rock core strength and the rock core property of the rock core sample; the geological information is forecasted according to the drilling speed, the drilling rock core recovery rate, the rock core strength and the rock core property, the forecasting process of the method is more timely, and the forecasting result is more accurate.

Description

Technical Field

[0001] The present application belongs to the technical field of tunnel excavation, and in particular, relates to a geological information prediction method for advance drilling under complex karst geological conditions. Background Art

[0002] As an important bauxite production base, southwest my country has developed karst landforms, with a karst area of ​​550,000 km2. Due to the uneven development of karst in karst areas, uneven bedrock surfaces, hidden groundwater, underground rivers, undercurrents, and caves, the construction conditions of underground projects in karst areas are complex, and geological disasters such as sudden water and mud, unstable rock formations and collapse are prone to occur, which may cause underground space and construction equipment to be buried or submerged, delay construction, increase underground project costs, seriously affect economic benefits, and even cause surface collapse, water source depletion, and major casualties. In addition, geological structures such as karst areas, faults, and caves were repeatedly exposed during tunnel excavation. The length of the karst section is close to half of the total length of the mining tunnel, and water and mud bursts, I-beam deformation, etc., occur, making maintenance very difficult.

[0003] The advance drilling method is currently the most direct and effective geological exploration method for predicting complex and unfavorable geological bodies in tunnels and lanes. It can currently conduct medium and long distance (0150m) detection and can accurately and intuitively reflect the surrounding rock geological conditions around the borehole. The principle is to use drilling equipment (such as impact drills, rotary drills, etc.) to drill in front of the face, and obtain rock strength, resistivity, elastic wave velocity and other indicators through core samples, thereby reflecting detailed information such as stratum lithology, rock mass integrity, fracture degree, karst caves, and fault filling status. The maximum acquisition of drilling parameter response information and efficient and rapid geological prediction are the current problems that need to be solved in drilling geological prediction. On the basis of the existing advance drilling prediction technology, the drilling data that can be collected at the drilling site are used to the maximum extent to make a refined prediction of the unknown strata of the tunnel, which is of great significance to ensure the safety of tunnel construction.

[0004] At present, in the advanced drilling geological prediction of actual projects, the results of drilling prediction are generally limited to the classification of the hardness of the surrounding rock or the rough judgment of the degree of development of the surrounding rock fractures based on the unstable oscillation of the drilling parameters. The fundamental reason is that the simultaneous analysis of multiple drilling parameters is not only inefficient but also cannot accurately predict the detailed characteristics of unknown formations, resulting in a large amount of useful drilling parameter response information being wasted and the misjudgment rate is extremely high. The existing technology requires a large number of experiments and data processing, which is time-consuming and labor-intensive. The evaluation results are not accurate enough and there are errors. In addition, the evaluation method lacks practicality and cannot be quickly applied in actual projects. Summary of the invention

[0005] The technical problem solved by this application is: how to more accurately and timely predict geological information during the advance drilling process.

[0006] The present application provides a geological information prediction method for advanced drilling under complex karst geological conditions, the geological information prediction method comprising:

[0007] During the advance drilling process, real-time acquisition of drilling data and core samples are obtained, wherein the drilling data includes drilling speed and drilling core sampling rate;

[0008] Determining the core strength and core properties of the core sample;

[0009] Geological information is predicted based on the drilling speed, the drilling core recovery rate, the core strength and the core properties.

[0010] Optionally, the method for determining the core strength and core properties of the core sample includes:

[0011] Identifying the core sample to determine the core properties of the core sample;

[0012] A strength test is performed on the core sample to determine the core strength of the core sample.

[0013] Optionally, the method for predicting geological information according to the drilling speed includes:

[0014] The hardness, crushing and cavity conditions of the rock mass in front of the tunnel are predicted according to the drilling speed.

[0015] Optionally, the method for predicting geological information according to the drilling core sampling rate includes:

[0016] The development of joints and fissures in the rock mass is determined based on the drilling core sampling rate to determine the integrity coefficient of the rock mass.

[0017] Optionally, the method for predicting geological information according to the core properties includes:

[0018] The distribution of different lithologic strata in front of the tunnel and the length of each lithologic stratum in the drilling direction are determined according to the core properties.

[0019] Optionally, the method for predicting geological information according to the core strength includes:

[0020] The rock strength at different lithology strata is determined based on the core strength to determine the surrounding rock grade of the tunnel.

[0021] The present application provides a geological information prediction method for advanced drilling under complex karst geological conditions, which has the following technical effects:

[0022] By predicting geological information through data such as drilling speed, core recovery rate, core strength and core properties, the forecast process is more timely and the forecast results are more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A flowchart of a geological information prediction method for advanced drilling under complex karst geological conditions according to one or more embodiments;

[0024] Figure 2 The present invention is a data denoising process according to one or more embodiments. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] Before describing the various embodiments of the present application in detail, the technical concept of the present application is first briefly described: it is currently difficult to timely and accurately predict geological information during advance drilling. To this end, the present application provides a geological information prediction method for advance drilling under complex karst geological conditions, which collects drilling data and obtains core samples in real time during the drilling process to obtain data such as drilling speed, borehole core sampling rate, core strength and core properties, and predicts geological information based on this, making the prediction process more timely and the prediction results more accurate. The specific principles of the geological information prediction method for advance drilling under complex karst geological conditions of the present application are described below in conjunction with more embodiments.

[0027] Specifically, Figure 1 As shown, the geological information prediction method for advance drilling under complex karst geological conditions in this embodiment 1 includes the following steps:

[0028] Step S10: collecting drilling data and obtaining core samples in real time during the advance drilling process, wherein the drilling data includes drilling speed and drilling core sampling rate;

[0029] Step S20, measuring the core strength and core properties of the core sample;

[0030] Step S30: Predict geological information based on drilling speed, drilling core recovery rate, core strength and core properties.

[0031] In one or more embodiments, after the drilling data is collected, data denoising is performed: due to platform vibration, sample unevenness, etc., there is a lot of noise in the pressure, flow, rotation speed, drilling speed, torque and vibration signals. Therefore, the embodiment uses the wavelet toolkit in Matlab to perform wavelet threshold denoising on the two parameters of thrust and torque. The wavelet threshold denoising method is to retain or remove the wavelet coefficients of the noisy drilling parameters under multi-scale decomposition through a specific threshold. The rule is to perform specific processing on the coefficients exceeding the set threshold, and set the coefficients less than the set threshold to zero. Finally, the wavelet coefficients processed by the threshold are reconstructed by wavelet inverse transform. The process is as follows: Figure 2 shown.

[0032] For example, a drilling response data acquisition system can be used to collect the operating parameters of the drilling rig during the drilling process of the drilling rig. The data acquisition process has the characteristics of real-time, automation, high sampling rate and high data accuracy. The system mainly includes a mining intrinsically safe industrial computer, a mining intrinsically safe data acquisition instrument, various mining monitoring sensors and mining intrinsically safe power supplies. Then the system is equipped with data acquisition software to realize the real-time and intelligent acquisition of various operating parameters such as pressure, speed, drilling depth, drilling angle, etc. during the drilling of the drilling rig.

[0033] Exemplarily, the method of predicting geological information based on drilling speed includes: predicting the hardness of the rock mass, the rock mass fragmentation and the cavity condition in front of the tunnel according to the drilling speed. Specifically, the drilling speed of the advance drilling rig is slow in hard rock mass and fast in soft rock mass. In addition, if there are cavities such as karst in the drilling section, the drilling speed will suddenly increase sharply. When the drill bit enters the rock mass fragmentation section or the fragmentation section on both sides of the fault, the drill is easily stuck and the drilling speed will decrease accordingly. Therefore, the geological conditions at each mileage can be inferred based on the drilling depth and the drilling speed at that location.

[0034] In one or more embodiments, the method for predicting geological information based on the core sampling rate of a borehole includes: determining the development of joints and fissures of a rock mass based on the core sampling rate of the borehole to determine the integrity coefficient of the rock mass. Specifically, the core sampling rate in a borehole can reflect the development of joints and fissures of a rock mass within the drilling depth, and to a considerable extent can reflect the integrity coefficient of the rock mass, thereby judging whether the rock mass is intact. When the core sampling rate is low, it indicates that the joints and fissures of the rock mass in the drilling area of ​​the borehole are relatively developed, and the integrity coefficient is low. On the contrary, if the core sampling rate is high, it indicates that the integrity of the rock mass is good, and the joints and fissures are basically not developed. Therefore, the degree of rock fragmentation at different locations can be judged based on the core sampling rate of each section.

[0035] In one or more embodiments, after obtaining the core samples, the drill cores are identified to determine the core properties, and further, the distribution of various lithological strata in front of the tunnel drilling excavation face can be predicted based on the core properties, such as location and approximate size, and the lengths of different lithological strata in the drilling direction can also be inferred.

[0036] Furthermore, after obtaining the core samples, the core samples are subjected to strength tests. Generally, a simpler method is used on site to determine the core strength, such as a point load test, so as to determine the rock strength in different lithology formations and provide a basis for determining the surrounding rock grade of the tunnel.

[0037] In one or more embodiments, a method for rapid tunneling under complex karst geological conditions comprises the following steps:

[0038] Step 1: Learn in detail about the geological structure, lithological characteristics, hydrogeological conditions and other information of the tunnel area, and analyze the unfavorable geological bodies that may be encountered, such as faults, fractured zones, karst, etc.

[0039] Step 2: Advance geological drilling. According to the engineering geological conditions, select appropriate advance drilling methods and geophysical exploration means. Determine the number, location, depth and detection frequency of drilling holes. Check and prepare the equipment required for drilling, including drilling rigs, drill rods, drill bits, flushing fluids, etc., and implement drilling. For karst caves, underground rivers or karst silt sections, the possibility of disasters such as sudden water and mud is relatively high, and the size and location of the karst cave are difficult to determine accurately. The groundwater has high mobility in the cracks and can be concentrated in a very small area. Therefore, in the above areas, 5 to 6 boreholes are generally arranged.

[0040] Step 3: Data collection. During the drilling process, pay attention to the changes in drilling speed, core identification, and the color and smell of the drilling fluid to obtain geological information; record the various data during the drilling process in detail, including drilling speed, core description, flushing fluid changes, etc.

[0041] Step 4: Rock mass determination: Conduct a detailed analysis of the extracted core to determine its lithology, joint and fissure development, weathering degree, etc.; infer the nature of the rock mass ahead based on the core characteristics.

[0042] Step 5: Data analysis. Summarize the data collected by the sensors, conduct a comprehensive comparison and analysis of the drilling data, form a comprehensive judgment of the geological conditions ahead, and determine the adverse geological bodies that may be encountered and their distribution range, scale and nature.

[0043] The specific implementation methods of the present application are described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirit of the present application whose scope is defined by the claims and their equivalents. These modifications and improvements should also be within the scope of protection of the present application.

Claims

1. A geological information prediction method for advanced drilling under complex karst geological conditions, characterized in that: The geological information prediction method comprises: During the advance drilling process, real-time acquisition of drilling data and core samples are obtained, wherein the drilling data includes drilling speed and drilling core sampling rate; Determining the core strength and core properties of the core sample; Geological information is predicted based on the drilling speed, the drilling core recovery rate, the core strength and the core properties.

2. The geological information prediction method for advanced drilling under complex karst geological conditions according to claim 1, characterized in that: The method for determining the core strength and core properties of the core sample comprises: Identifying the core sample to determine the core properties of the core sample; A strength test is performed on the core sample to determine the core strength of the core sample.

3. The geological information prediction method for advanced drilling under complex karst geological conditions according to claim 1, characterized in that: The method for predicting geological information according to the drilling speed includes: The hardness, crushing and cavity conditions of the rock mass in front of the tunnel are predicted according to the drilling speed.

4. The geological information prediction method for advanced drilling under complex karst geological conditions according to claim 1, characterized in that: The method for predicting geological information according to the drilling core sampling rate includes: The development of joints and fissures in the rock mass is determined based on the drilling core sampling rate to determine the integrity coefficient of the rock mass.

5. The geological information prediction method for advanced drilling under complex karst geological conditions according to claim 1, characterized in that: The method for predicting geological information according to the core properties includes: The distribution of different lithologic strata in front of the tunnel and the length of each lithologic stratum in the drilling direction are determined according to the core properties.

6. The geological information prediction method for advanced drilling under complex karst geological conditions according to claim 1, characterized in that: The method for predicting geological information based on the core strength includes: determining the rock strength at different lithology strata based on the core strength to determine the surrounding rock grade of the tunnel.

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