Hydrogeological exploration hole layered pumping control system and method thereof

Abstract

A hydrogeological exploration hole layered pumping control method and system. Including well structure, external layered water stop, internal layered packer and layered pumping and monitoring modules; The method comprises geological data analysis and layered model construction, collaborative well structure and water stop scheme design, internal and external combined construction, layered pumping and synchronous monitoring, data integration and parameter calculation. The invention adopts a stepped variable diameter structure well design, combined with long-term water stop of external water-swelling material and temporary recyclable sealing of internal inflatable packer, forming an internal and external collaborative double sealing structure, and synchronously monitoring the water level of the adjacent layers and observation holes during pumping; The pumping pump is placed in the upper pump chamber section, which reduces the requirement for the lower well section aperture, significantly reduces the overall well structure size, and reduces the cost. The method solves the problems of poor water stop reliability and insufficient hydrogeological parameter accuracy, realizes single-hole multi-layer fine exploration, and improves the exploration efficiency and data accuracy.

Description

Technical Field

[0001] This invention relates to a pumping control system and method, and more particularly to a stratified pumping control system and method for hydrogeological exploration boreholes, belonging to the field of geological exploration technology. Background Technology

[0002] In the fields of coal mine safety production and hydrogeological exploration, accurately identifying the water-bearing characteristics, hydrogeological parameters, and hydraulic connections between major aquifers in a mining area is crucial for predicting mine water inflow and designing water control measures. Among these methods, stratified pumping tests are the most direct and reliable technical means to obtain these key hydrogeological parameters. Their core function is to isolate the target aquifer using technical means and conduct independent pumping and observation of that stratum, thereby accurately obtaining parameters such as the permeability coefficient and water inflow of that stratum, avoiding mutual interference between different aquifers, and improving exploration accuracy.

[0003] Currently, the technical solutions used domestically and internationally for implementing stratified pumping in hydrogeological exploration boreholes can be mainly divided into the following two categories:

[0004] Category 1: Traditional multi-layer sleeve reducing diameter water-stopping solution.

[0005] This scheme employs a multi-section wellbore structure, using varying diameter casings at different depths and running multiple layers of casing with progressively decreasing diameters. Differential trays and materials such as clay balls or cement mortar are used to seal off aquifers outside the target layer. While this scheme provides good sealing, it is costly in terms of pipe materials, time-consuming, and inefficient. If multiple (e.g., three) aquifers are to be pumped in strata within a single borehole, a minimum of four sections is required. This results in a minimum well diameter of 152mm for a final borehole casing diameter of 108mm plus pump chamber diameter variation; 177.8mm for a three-section section (251mm); 273mm for a two-section section (342mm); and 377mm for a one-section section (444mm). This scheme has significant drawbacks.

[0006] On the one hand, it greatly increases the difficulty of construction, requires multiple layers of casing and water-stopping materials, which greatly increases the cost and the drilling cycle is affected by the water pumping test, which greatly increases the construction period; on the other hand, when the diameter section is sealed with a tray, "the sealing effect of the diameter section is poor, water inrush is likely to occur in the upper and lower layers of the water-bearing target layer, and the accuracy of the obtained hydrogeological parameters is not high."

[0007] Category 2: Single-layer, single-well, stratified pumping scheme.

[0008] This scheme involves drilling and completing a separate well for each target aquifer, meaning "four separate wells need to be drilled for the four target aquifers, with casing installed for each, and water sealing outside the target aquifers." While this scheme avoids complex, permanent water-sealing structures within the same borehole, its drawbacks are more pronounced:

[0009] Its characteristics include "more wells, higher material consumption, higher costs, longer pumping test time, and lower efficiency." If multi-well stratified pumping is adopted, the drilling footage and casing will be significantly increased (especially when the hole depth exceeds 800m), and the cost will also surge.

[0010] To overcome the shortcomings of traditional methods, both domestic and international researchers have begun exploring the use of packer technology for stratified water sealing within the same diameter. Packer technology originated in the petroleum industry; its working principle involves expanding a rubber sleeve using hydraulic, pneumatic, or mechanical means to seal the target section within the wellbore. Currently, the application of this technology in the field of hydrogeology still faces numerous challenges.

[0011] First, oilfield packers are prone to problems such as "mid-way setting, automatic unsealing, cross-sealing, creep, seal failure, and mis-sealing" in complex downhole environments. Second, even the relatively advanced K344 hydraulic packer, improved by the China Geological Survey, has persistent problems in actual hydrogeological exploration applications: "On the one hand, there is the problem of packer failure, caused by factors such as air leakage, pressure loss, rubber sleeve cracking, and poor sealing performance; on the other hand, the rubber sleeve expansion ratio is small, often around 1.3 in China, while the maximum expansion ratio abroad can reach 3.0, the determining factor being the rubber sleeve material performance." These problems directly lead to "the obtained groundwater parameters not accurately reflecting the groundwater flow field."

[0012] Therefore, whether it is the traditional variable diameter water stop or the early packer technology, the system is difficult to achieve "a single well can only conduct a few layers of stratified pumping tests, and cannot monitor the water level, water temperature and other parameters of each layer in real time", which greatly limits the utilization rate of the borehole and the comprehensiveness of the data.

[0013] In traditional schemes, even with a constant-diameter wellbore structure, a combination of "pallet sealing, clay ball sealing, and water-swellable rubber" is often used. However, this also has drawbacks: traditional water-swellable rubber expands slowly, resulting in a long setting time; multi-stage pumping tests cannot be conducted, leading to low borehole utilization; and the sealing performance is poor, resulting in low accuracy of the obtained hydrogeological parameters. Furthermore, in traditional stratified pumping schemes, because the pumping equipment needs to be lowered into the target aquifer, the well diameter is often progressively increased (e.g., Φ444mm for the initial drilling, but only Φ108mm for the final drilling), causing material waste, increased construction difficulty, and extended construction time.

[0014] In summary, existing stratified pumping technologies for hydrogeological exploration wells, whether traditional multi-casing schemes, single-layer single-well schemes, or the still-developing early packer schemes, generally suffer from a series of drawbacks, including low construction efficiency, high economic costs, complex well completion processes, insufficient reliability of water-stopping seals, limited accuracy of obtained hydrogeological parameters, and difficulty in achieving real-time monitoring of multiple layers within a single well. These shortcomings severely restrict the feasibility and effectiveness of fine-grained hydrogeological exploration in mining areas with complex hydrogeological conditions, such as the Sijitun Coal Mine. Therefore, there is an urgent need for a new stratified pumping control system and method that can comprehensively address the aforementioned deficiencies. Summary of the Invention

[0015] To address the shortcomings of existing technologies, this invention discloses a method for controlling stratified pumping in hydrogeological exploration boreholes, the technical solution of which is as follows:

[0016] A method for controlling stratified pumping in hydrogeological exploration wells includes the following steps:

[0017] S1. Collect and integrate borehole core, geophysical logging and hydrological logging data of the exploration area; based on multi-source data fusion and lithology-physical property correlation analysis, establish identification rules to accurately divide multiple main aquifers and relative impermeable layers in the vertical direction; and construct a three-dimensional digital hydrogeological stratification model including stratigraphic planes, properties, thickness and parameter fields through inter-well comparison and spatial interpolation.

[0018] S2. Based on the digital layered model described in S1, the well structure is optimized with the pumping equipment size as a constraint: the depth of the surface casing used to isolate shallow aquifers is determined; and a stepped diameter casing combination is designed for the target section, wherein solid pipes are arranged at the relative aquifer positions determined by the model, and water-swellable sealing material is pre-installed on the outside of the solid pipe sections, and perforated pipes are arranged at the aquifer positions; the design ensures that a pump chamber section for accommodating the pump is formed in the upper main aquifer section;

[0019] S3. Drilling, casing installation, and cementing operations are carried out according to the design in S2, causing the water-swellable sealing material to expand in the formation water, forming a primary long-lasting seal; subsequently, an air-expanding packer string controlled by a surface gas source control unit is lowered into the well and positioned at the upper and lower aquitards corresponding to the target pumping section; the setting pressure is dynamically calculated and applied based on the downhole hydrostatic pressure to set the packer, forming a secondary reversible seal; the external primary seal and the internal secondary seal together constitute a dual sealing structure with internal and external coordination, forming an independent pumping chamber hydraulically isolated from the upper and lower sections;

[0020] S4. Conduct a pumping test in the independent pumping chamber formed in S3; at the same time, monitor the drawdown of the pumping section, the water level changes of the adjacent non-pumping sections in the pumping hole, and monitor the water level response of the surrounding observation holes through the water level sensors of the perforated pipe sections of each aquifer pre-installed in the pumping hole.

[0021] S5. Integrate the synchronous time series data obtained in S4, including pumping volume, drawdown of the current layer, water level changes of adjacent layers, and water level changes of observation wells; use the multi-layer aquifer system theoretical model and parameter numerical inversion algorithm to simultaneously fit the multi-source water level response data, calculate the permeability coefficient, storage coefficient, and interlayer overflow coefficient of each aquifer, and update the parameter field in the digital layered model constructed in S1 to form a high-precision hydrogeological model.

[0022] Preferably, in step S1, the "construction of a three-dimensional digital hydrogeological stratification model based on multi-source data fusion and lithology-physical property correlation analysis" specifically includes:

[0023] Using borehole core logging data as training labels and geophysical logging curves as features, a lithology classification model is trained to generate predicted lithology profiles of boreholes.

[0024] Based on the preset aquifer and relative impermeable layer identification rules, the predicted lithological profile is scanned to identify the top and bottom depths of each aquifer and relative impermeable layer.

[0025] By using inter-well comparison and geostatistical spatial interpolation methods, the top and bottom surfaces of the same relative impermeable layer or main aquifer in each borehole are connected to generate a three-dimensional stratigraphic plane that is continuously distributed throughout the area, thereby constructing a structured stratigraphic model consisting of stratigraphic plane sequence, hydrogeological properties, thickness field and parameter field.

[0026] The lithology classification model employs a bidirectional LSTM network based on an attention mechanism. Its input is a multi-channel well logging curve time series, and its output is a lithology probability distribution. The network loss function is: L = α·L_ce + β·L_smooth; where: L_ce is the cross-entropy loss; L_smooth is the smoothing loss of lithology labels at adjacent depths to avoid frequent lithology jumps; α and β are weight coefficients, determined through grid search. This model can maintain high-resolution lithology identification accuracy even in well sections without coring, providing a reliable basis for aquifer / aquitard delineation.

[0027] Preferably, in step S3, the "dynamic calculation and application of setting pressure" specifically refers to:

[0028] According to the formula P_set seal = (H_packer - H_static water level) / 100 + P 附加Calculate the theoretical setting pressure, where H (packer) and H (static water level) are in meters, and P (setting pressure) and P (setting pressure) are in meters. 附加 The unit is megapascals (MPa), where P is the additional pressure used to overcome resistance and ensure a seal; "100" is the water column pressure coefficient, i.e., 0.01 MPa / m, which is the unit weight of water.

[0029] P 附加 = k·ρ·g·Δh / 10 6 ;

[0030] Where: k is the safety factor (recommended 1.2-1.5); ρ is the groundwater density (kg / m³); g is the gravitational acceleration (9.8 m / s²); Δh is the effective sealing section height of the packer sleeve (m);

[0031] The ground-based gas source control unit implements a step-by-step pressure stabilization-feedback adjustment strategy: first, the pressure is applied to 80% of the theoretical pressure and stabilized for observation. If the pressure does not decrease, a PID control algorithm is activated to gradually increase the pressure to the theoretical pressure value, and continuous adjustment is made throughout the stabilization process to maintain pressure stability. The dynamic control of the setting pressure adopts an adaptive PID control algorithm, and its control law is as follows:

[0032] Where: u(t): control output, i.e. the setting pressure (MPa) to be applied;

[0033] e(t) = P target -P actual (t): Pressure deviation;

[0034] P target : The target is to be sealed off from pressure;

[0035] P actual (t): Real-time monitored pressure inside the packer;

[0036] Kp, Ki, Kd: PID parameters, dynamically adjusted according to well depth and formation lithology. The adjustment strategy is as follows:

[0037]

[0038] H: Packer depth (m);

[0039] K p0 ,K i0 ,K d0 Baseline PID parameters;

[0040] γ,λ,δ: Depth influence coefficients, calibrated through downhole tests.

[0041] This adaptive PID algorithm can effectively compensate for pressure drift caused by changes in well depth, rubber sleeve creep, and temperature fluctuations, ensuring long-term and stable sealing.

[0042] Preferably, the three-dimensional digital hydrogeological stratification model constructed in step S1 is a structure-attribute model formally defined as G = (H, A, T, P, R), where: H is an ordered set of stratigraphic horizon functions that map planar coordinates to elevation and depth; A is the hydrogeological attribute of each stratum unit divided based on the horizon, and its value is "aquifer" or "relative impermeable layer"; T is the thickness field of each stratum unit; P is the hydrogeological parameter field of each stratum unit; and R is the effective spatial range of the model.

[0043] Preferably, the method involves repeatedly performing steps S3 and S4 in a single well for multiple aquifers to achieve a stratified pumping test of multiple aquifers in a single well.

[0044] Preferably, in step S4, the monitoring data obtained from "synchronously monitoring the water level changes in adjacent non-pumping sections within the pumping hole" is used to verify the isolation effectiveness of the internal and external synergistic double sealing structure in real time.

[0045] Preferably, the parameter numerical inversion algorithm adopts the multi-objective genetic algorithm (NSGA-II), and the objective function is:

[0046] minF(θ)=[f1(θ),f2(θ)]

[0047] Where: θ is the parameter vector to be inverted; including the permeability coefficient K, water storage coefficient S and interlayer overflow coefficient μ of each aquifer, i.e. θ=[K1,S1,μ1,K2,S2,μ2,…];

[0048] f1(θ) is the fitting error of the pumping layer, and its calculation formula is: ;

[0049] Where: T is the total number of time steps in the pumping test; s obs (t) represents the water level drawdown (m) observed at the t-th time step of the pumping layer;

[0050] s sim (t,θ) represents the water level drawdown (m) of the pumping layer obtained by numerical simulation using the parameter vector θ at the t-th time step.

[0051] f2(θ) is the fitting error of the observation layer (including the adjacent non-pumping layer and the corresponding layer of the observation well), and the calculation formula is: ;

[0052] M represents the total number of observation layers (including the non-pumping layers adjacent to this well and the corresponding layer of the observation well).

[0053] h obs,i (t) represents the water level (m) observed by the i-th observation layer at the t-th time step;

[0054] h sim,i (t,θ) represents the water level (m) obtained by the i-th observation layer at the t-th time step through numerical model simulation using the parameter vector θ.

[0055] The two objective functions are optimized using the NSGA-II algorithm to obtain the Pareto optimal solution set. To select the final solution from the Pareto optimal solution set, a model complexity penalty term is introduced, with the selection criterion being:

[0056] in: The L1 norm of the parameter vector is the sum of the absolute values ​​of the parameters, which is used to promote parameter sparsity.

[0057] TV(θ) is the total variation of the parameter field, used to smooth the spatial distribution of the parameters. Its calculation formula is:

[0058] Here N layers The number of aquifers. and These are the gradient operators in the horizontal and vertical directions, respectively (for layered aquifers, only the horizontal variation is usually considered); λ is the regularization coefficient, used to balance data fitting error and model complexity, and is usually determined through cross-validation.

[0059] In step S5, based on the acquired synchronous time series data, a multi-objective genetic algorithm (NSGA-II) is used for parameter inversion. Two objective functions are defined: pumping layer fitting error f1 and observation layer fitting error f2, which respectively measure the differences between the simulated and observed pumping layer drawdown and the observed water level. By simultaneously minimizing these two objective functions, a set of Pareto optimal solutions is obtained. To select the final solution, a model complexity penalty term (including parameter sparsity and spatial smoothness) is introduced to avoid overfitting and improve the physical rationality and stability of the parameter solutions.

[0060] Preferably, in order to objectively and quantitatively verify and evaluate the isolation effect of the "internal and external synergistic double sealing structure" in real time, an isolation efficiency coefficient η is defined. iso As a core quantitative indicator, the efficiency coefficient η is used for isolation. iso Quantitative evaluation of sealing effectiveness:

[0061] Where: η iso The closer η is to 1, the less disturbance the non-pumping layer experiences, and the more perfect the sealing and isolation effect;iso A value significantly less than 1 indicates interlayer overflow or seal failure;

[0062] Δh pump Drawdown of the pumping layer, meters (m).

[0063] Δh i , the water level change of the i-th adjacent non-pumping layer; meters (m), the amplitude of the water level change of the i-th non-pumping layer relative to its initial static water level during the pumping test;

[0064] wi is the weight coefficient of the i-th adjacent layer, used to quantify the strength of the natural hydraulic connection between this adjacent layer and the pumping layer. The stronger the hydraulic connection, the stronger the "evidence" of a change in the water level of this layer for seal failure, and the larger its weight wi.

[0065] N represents the total number of adjacent non-pumping layers participating in the evaluation; within the pumping well, the number of other major aquifers selected to verify the isolation effect, excluding the target pumping layer. It typically includes the immediately adjacent upper layer (m-1) and lower layer (m+1).

[0066] I, the index variable, is the adjacent non-pumping layer number, i = 1, 2, ..., N, representing the i-th monitored adjacent non-pumping layer.

[0067] This invention also discloses a stratified pumping control system for hydrogeological exploration wells, used to execute the above-described method, comprising:

[0068] The wellbore structure module is used to construct a borehole structure that can reach multiple target aquifers. It includes a surface casing unit for isolating shallow aquifers and a target layer casing unit for penetrating the target aquifer and the impermeable layer. The target layer casing unit includes a solid pipe section set at the impermeable layer position according to the hydrogeological stratification model and a perforated pipe section set at the aquifer position.

[0069] The external layered water-stopping module, which cooperates with the solid pipe section of the well body structure module, includes a water-swellable water-stopping material placed on the outside of the solid pipe section, used to form a long-term seal between the borehole wall and the casing.

[0070] The internal layered packer module includes at least one set of inflatable packers that can be lowered into the well via drill pipe, and a surface gas source control unit that provides a pressure source for the packers and can dynamically control the setting pressure according to the method of claim 3. The packers are used to set at the upper and lower aquitard positions of the target pumping section.

[0071] The stratified pumping and monitoring module includes a pump installed in an independent pumping chamber formed by upper and lower packers, a water level monitoring unit for monitoring the water level in the pumping section and adjacent non-pumping sections, and a cable and pipeline unit connecting the ground and downhole equipment.

[0072] The external layered water-stopping module and the internal layered sealing module together form a double sealing structure that works in tandem to ensure effective isolation of each aquifer during the pumping test. The well structure module also includes a pump chamber section located in the upper target aquifer section, where the pump of the layered pumping and monitoring module is located.

[0073] Preferably, the target layer casing unit adopts a stepped variable diameter structure, that is, a casing assembly with a first diameter is used in the upper section of the borehole where the main target aquifer is located, and a casing with a second diameter smaller than the first diameter is used in the lower section of the borehole below the upper section.

[0074] Preferably, the pump position of the stratified pumping and monitoring module can be adjusted up and down along the pumping chamber to adapt to the water discharge characteristics of different aquifers.

[0075] Preferably, the pump of the stratified pumping and monitoring module is located in the pump chamber section, so that the lower well section is no longer limited by the size of the pumping equipment, thereby allowing the use of smaller diameter casing and well structure.

[0076] Compared with the prior art, the technical solution of the present invention has achieved significant progress through the following collaborative and innovative technical means:

[0077] 1. Addressing the issues of "low construction efficiency and high cost": The stepped variable diameter structure design based on digital models enables continuous exploration of multiple aquifers within a single borehole. This completely eliminates the traditional multi-layer variable diameter or single-layer single-well model, shortening the well completion cycle by more than 50%, and significantly reducing the borehole diameter and casing usage in deep well sections, thereby lowering the overall cost by approximately 30-40%.

[0078] 2. Addressing the core issues of "poor reliability of water-stop sealing and insufficient parameter accuracy": A "dual sealing structure with internal and external coordination" is adopted. This structure is not a simple stacking of components, but rather a complementary redundancy in function and space achieved through the long-lasting seal of the external water-swellable material and the adjustable pressure and reversible seal of the internal air-expanding packer. This design physically eliminates interlayer flow, providing a reliable guarantee for obtaining hydrological data from a single aquifer, and improving the accuracy of hydrogeological parameters (such as the permeability coefficient K) by an order of magnitude.

[0079] 3. Addressing the issues of "unverifiable water-stopping effect and low borehole utilization": An innovative verification network was constructed through "layered pumping and distributed synchronous monitoring." While pumping water from the target layer, water level data from adjacent layers is simultaneously acquired, allowing for direct and quantitative online determination of seal failure. This upgrades the traditional unreliable test of "assuming effective water-stopping" to a reliable integrated "pumping-verification" process, while simultaneously enabling real-time monitoring of multiple aquifers from a single borehole, increasing borehole utilization by 2-3 times.

[0080] 4. Addressing the issue of poor adaptability to deep and complex environments: Through the "dynamic calculation and feedback adjustment strategy of setting pressure", the system can intelligently adapt to changes in different well depths, hydrostatic pressures and formation conditions, effectively avoiding accidents such as "mid-way setting and automatic unsealing" of traditional packers, and significantly improving the success rate and safety of operations in deep holes (>800m) and complex formations. Attached Figure Description

[0081] Figure 1 This is a schematic diagram of the hydrogeological exploration borehole stratified pumping control system of the present invention; the attached figure shows the well structure, external stratified water stop, internal stratified isolation, and the coordinated layout of the stratified pumping and monitoring modules;

[0082] Figure 2 This is a schematic diagram of the well structure module of the present invention. The attached figure shows the arrangement of the first and second opening stages, the solid pipe and the slotted pipe.

[0083] Figure 3 This is a schematic diagram of the internal and external cooperative sealing structure of the present invention.

[0084] Figure 4 This is a schematic diagram of the process for controlling the stratified pumping of hydrogeological exploration boreholes according to the present invention, showing the steps from geological analysis to parameter calculation. Detailed Implementation

[0085] Example 1

[0086] To minimize drilling and casing costs in deep well sections while ensuring smooth installation of the pumping equipment, this invention employs an optimized wellbore structure design of "larger at the top and smaller at the bottom, with stepped diameter changes." Specifically, in the upper part of the borehole (typically covering the main target aquifer and above), a larger well diameter and casing of a corresponding diameter (e.g., Φ244.5mm) are used to form an "equipment working section" capable of accommodating the pump, packer, and monitoring equipment. Below this section, up to the end of the borehole, significantly smaller well diameters and casing (e.g., Φ177.8mm or smaller) are used, only needing to meet the basic requirements of hydrological observation and formation exploration. The internal layered packer module and layered pumping and monitoring module used in this system are mainly installed and operate within the "equipment working section." Through this design, while achieving multi-layered fine pumping and monitoring in a single borehole, the drilling footage and casing usage in deep, small-diameter well sections are significantly reduced, thereby significantly lowering the overall cost.

[0087] See Figure 1 As shown, this embodiment discloses a stratified pumping control system for hydrogeological exploration wells. This system achieves efficient and precise stratified pumping through the coordinated operation of the following specific modules. The terms "first aquifer," "second aquifer," "first relatively impermeable layer," and "second relatively impermeable layer" mentioned in this embodiment are exemplary strata defined based on the geological conditions of the specific exploration area. In practical applications, these terms need to be adjusted according to the actual hydrogeological structure of the target work area.

[0088] Wellbore structure module

[0089] The design of this wellbore structure module follows the principle of "cost optimization under pump chamber constraints." Its core design methods include:

[0090] 1. Theoretical Definition of Pump Chamber Section: First, based on the outer diameter of the pumps and packers in the selected stratified pumping and monitoring modules, determine the minimum necessary well diameter D_pump to ensure their safe entry and operation. The section in the borehole where these devices need to be installed is defined as the "equipment working section." 2. Stepped Diameter Optimization Model: Based on the geological stratification model, establish an optimization function with the objective of minimizing the total well construction cost. Decision variables include the well diameter and casing diameter of the equipment working section (≥D_pump), the well diameter and casing diameter of the lower exploration section (which can be much smaller than D_pump), and the depth of the diameter change point. Constraints include casing strength, annular clearance requirements, and the installation space requirements of the external stratified water-stopping modules.

[0091] See Figure 2 As shown, a borehole physical structure is constructed that can effectively isolate non-target aquifers while providing a stable channel and installation foundation for subsequent stratified pumping and monitoring. Its core objective is to achieve "multi-layer" exploration within a single borehole. Figure 2 Demonstrating the "two-stage" construction process (first and second phases):

[0092] The initial drilling stage represents the initial construction phase of the borehole. Using a large-diameter drill bit (e.g., Φ444mm) (the initial drilling bit), the borehole is drilled to the top boundary of the target aquifer. Then, surface casing is run in and permanently cemented. The core function of this stage is to isolate shallow, non-target aquifers (such as Quaternary or Neogene aquifers) to prevent their water from interfering with subsequent testing of the deeper, primary target aquifer, while simultaneously establishing a stable wellhead.

[0093] The second stage represents the fine-tuning phase of drilling. After coring and logging using a small-diameter drill bit within the first casing, the borehole is enlarged to the final depth using a medium-diameter drill bit. Then, the target layer casing unit is run in. This stage is the core of implementing the layered technology of this invention.

[0094] In the second stage, the structural changes are reflected in the fact that although the casing diameter is the same, it is divided into solid casing and perforated casing according to its function.

[0095] Solid pipe (impermeable pipe): Precisely inserted into the relative impermeable layer positions determined by the geological model (as marked M1 and M2 in the figure). Its function is to block water flow and provide a structural basis for internal and external waterproofing.

[0096] A perforated pipe (water filter pipe): This is precisely inserted into the aquifer location (as marked in the diagram). Its function is to guide water flow, allowing groundwater from the target aquifer to flow smoothly into the well.

[0097] Appendix Figure 2 The sequence of "Third Aquifer → M2 Impermeable Layer → Second Aquifer → M1 Impermeable Layer → First Aquifer" clearly demonstrates how a thick, heterogeneous aquifer system is vertically divided into several aquifer sections (First, Second, and Third Aquifers) using relative impermeable layers (M1, M2). The solid tubing in the wellbore structure is precisely aligned with the impermeable layers, and the perforated tubing is precisely aligned with the aquifer sections.

[0098] The attached diagram provides a visual definition and detailed implementation of the "wellbore structure module," which, through a stepped variable diameter structure design, creates a standardized, efficient, and low-cost working environment within a single borehole for subsequent layered monitoring.

[0099] Composition and working principle of the wellbore structure modules:

[0100] Surface casing unit: consists of large-diameter oil casing or geological casing and its couplings.

[0101] Working principle and process: In the first stage of drilling (usually called "first stage"), a larger diameter drill bit is used to drill to a certain depth below the top boundary of the main target aquifer. Then, a surface casing with an inlet diameter slightly smaller than the drill bit is installed, and cement slurry is injected into the annular gap between the casing and the borehole wall for permanent cementing and water sealing. Its function is to seal the shallow aquifer, prevent water from entering the borehole and interfering with the testing of the lower main target layer, and provide wellhead support for subsequent construction.

[0102] Target layer casing unit: It adopts a "stepped diameter structure" design, which is composed of solid pipes (impermeable seamless steel pipes) and perforated pipes (i.e. filter pipes, with perforated pipe walls and wrapped with filter screens to allow groundwater to seep in) in different layers.

[0103] Working Principle and Process: In the second stage (commonly known as "second-stage drilling"), core drilling is first performed using a small-diameter drill bit to the final borehole, followed by geophysical logging to accurately distinguish between the aquifer and the impermeable layer. Subsequently, a larger-diameter drill bit is used for borehole reaming. Afterwards, based on the geological analysis results, solid casing is run into the section corresponding to the impermeable layer, and slotted casing is run into the section corresponding to the aquifer. All casing is connected to the surface casing via reducing couplings. The slotted casing allows groundwater from the corresponding aquifer to flow freely into the well, while the solid casing acts as a barrier and provides the structural basis for internal and external water sealing.

[0104] This module provides the basic well environment for the entire system. Its main pipe section provides anchoring and construction working surface for the external layered water-stopping module; its perforated pipe section provides the isolation position selection for the internal layered sealing module, and provides groundwater inflow channels and sensor installation space for the layered pumping and monitoring module.

[0105] Compared to traditional technologies that force the entire well to have a large diameter to accommodate deep equipment (resulting in a "coarse overall" design) or use a small diameter to save money (resulting in equipment being unable to be lowered), this invention achieves a well structure where "the upper working section meets functional requirements, while the lower exploration section achieves economic optimization." This represents a quantification and deepening of the "stepped diameter" design concept, bringing significant progress in engineering economics.

[0106] External layered water-stopping module:

[0107] Between the target layer casing and the borehole wall, a first long-term stable external seal (i.e., long-term seal or primary seal) is formed at the location of the relative aquitard to block potential water flow channels in the casing annulus.

[0108] Composition: Includes water-swellable sealing materials, such as water-swellable rubber or similar materials. These materials are made into tapes, ropes, or specific prefabricated components.

[0109] Working principle and process: Before the target layer casing unit is run into the well, it is wrapped or installed at a specific location on the outer wall of its casing section (i.e., corresponding to the location of the relative aquitard layer downhole). For example, several meters of water-swellable tape are wrapped around the upper and lower ends of the casing corresponding to each relative aquitard layer section to be sealed. After the casing is in place, the sealing material comes into contact with the groundwater in the formation, undergoes volume expansion, and tightly fills the annular gap between the casing and the borehole wall, thereby forming a primary seal (long-term seal).

[0110] See Figure 3 As shown, the synergistic effect of external layered water-stopping and internal layered sealing forms a highly reliable structure to solve the problem of sealing failure caused by a single water-stopping method. This module works closely with the solid pipe section of the wellbore structure module. Together with the internal layered sealing module, it forms the structure, and the internal and external collaboration greatly improves the reliability of the sealing.

[0111] The outer casing is wrapped with a material representing a water-swellable sealing material (such as water-swellable rubber tape). This material makes close contact with the external borehole wall, forming a ring-shaped seal. This structure is the long-term seal (i.e., the primary seal). Its function is to seal the annular space between the outer wall of the casing and the borehole wall, preventing water from the aquifer from flowing vertically through this annulus. This is the first barrier. Inside the casing, there are two inflatable packers with rubber sleeves. After being pressurized, the packer sleeves expand radially and fit tightly against the inner wall of the casing, forming a strong seal. This structure is the internal layered packer or secondary seal. Its function is to seal the inner wall of the casing, ensuring that the isolated well section is also independent inside the casing. This is the second barrier.

[0112] The water-sealant material for the external layered water-sealant module is preferably water-swellable rubber (WSR) with a high expansion rate and fast expansion speed, formulated with optimized properties. Its performance indicators meet the following requirements: volume expansion rate ≥150% and basic expansion time ≤24 hours in groundwater at normal temperature, to meet the requirements of the exploration period. The installation method includes quantitative design: the length L of the water-sealant material wound around the outside of the solid pipe section corresponding to the relative impermeable layer must satisfy: L ≥ kπ(D_hole - D_casing), where D_hole is the borehole diameter, D_casing is the casing outer diameter, and k is an empirical safety factor (usually k≥3). This design ensures that the expandable body has sufficient volume to fill and compact the annular space, forming a reliable long-lasting seal. Through the optimization of material performance indicators and the quantitative design of the winding length, external water sealing is elevated from an experience-dependent process to a predictable and controllable technical step, fundamentally improving its reliability as the "first line of defense."

[0113] Appendix Figure 3This indicates that a long-lasting seal, meaning that the primary seal (external) and the secondary seal (internal) function simultaneously at two locations above and below the same well section. They work together, one internal and one external, to clamp the casing and the rock wall, forming a complete and redundant sealing system. Even if the effectiveness of one seal decreases slightly for some reason, the other seal can still effectively maintain the isolation state.

[0114] Between the upper and lower packers, an independent space is enclosed within the casing, forming an independent pumping chamber. This chamber is connected to the target aquifer through a perforated pipe section (not shown in this figure) at the corresponding aquifer location, while being strictly isolated from other aquifers above and below by the structure.

[0115] Internal layered enclosure module

[0116] Inside the existing wellbore, the target pumping section is precisely and reversibly temporarily sealed off, thereby creating an independent pumping chamber within the well.

[0117] The internal layered enclosure module consists of the following components:

[0118] (1) Inflatable expansion packer: mainly includes components such as central tube, rubber sleeve, upper and lower connectors and air inlet channel. Usually, at least one set (two packers, upper and lower) is required to isolate a layer. Preferably, the inflatable expansion packer is about 1.2-1.5m in length, the central tube diameter is not less than 89mm, and the design pressure bearing capacity is 10-30MPa to adapt to the hydrostatic pressure and pumping pressure difference requirements of different well depths.

[0119] (2) Surface gas source control unit: including high-pressure gas cylinders (such as nitrogen cylinders), pressure regulating valves, pressure gauges and high-pressure gas pipelines connected to the well.

[0120] Working principle and process:

[0121] Lowering: The connected upper and lower packers, water pump, and monitoring sensors are lowered via drill pipe or tubing to the corresponding upper and lower impermeable layers of the target aquifer. The lowering process must be smooth and slow to prevent premature setting or damage to the equipment.

[0122] In a preferred embodiment of the invention, the pump is located in the upper pump chamber section of the independent pumping chamber. This design eliminates the need to enlarge the diameter of the perforated and solid casings in the lower aquifer section to accommodate the pump, allowing the use of casings with a diameter of Φ177.8mm or even smaller, thereby achieving a compact wellbore structure and optimized cost.

[0123] Setting: High-pressure gas is injected into the sealed chamber of the packer through the gas pipeline. The setting pressure needs to be calculated based on the well depth and hydrostatic pressure. The calculation formula is: Setting pressure (MPa) = [Packer depth (m) - Hydrostatic depth (m)] / 100 + Additional pressure (MPa, e.g., 0.8MPa is an example value for the additional safety pressure, and "100" is the water column pressure coefficient (approximately 0.01 MPa / m)). After inflation, the packer expands radially, adhering tightly to the inner wall of the solid casing unit of the target layer, thus achieving setting. After setting, pressure stabilization and observation are required. If no pressure drop is confirmed, the seal is effective.

[0124] The surface gas source control unit calculates the initial setting pressure based on the formula P_setting = (H_packer - H_static water level) / 100 + P_additional pressure, but does not apply it all at once. It employs a dynamic setting control strategy of "gradual pressure stabilization-feedback adjustment": first, it pressurizes to 80% of the calculated value, stabilizing the pressure by observing the pressure gauge and downhole pressure sensor data; if the pressure stabilizes, it slowly increases to 100%; if the pressure drop exceeds a threshold (e.g., 0.5 MPa / min), it is judged as a poor seal, requiring readjustment or equipment inspection. After successful setting, the system continuously monitors the pressure, achieving closed-loop control. This dynamic control strategy effectively avoids problems such as insufficient setting or overpressure damage to the packer caused by calculation errors or minor changes in downhole conditions, significantly improving the success rate and reliability of packer sealing in complex formations.

[0125] Unsealing: After the pumping test is completed, the internal pressure of the packer is released through ground control, the rubber sleeve contracts, and it can be safely pulled out of the well.

[0126] This module is the core of stratified pumping, operating directly within the wellbore created by the well structure module. Its setting position strictly depends on the relative impermeable layer determined by geological analysis. Through collaboration with the stratified pumping and monitoring module, it creates an independent working environment for the pumps.

[0127] The system employs an internal layered sealing module and an external layered water-stopping module to form a synergistic dual-sealing structure. The external water-stopping module creates a durable seal; once expansion is complete, it forms a long-term, stable isolation barrier outside the casing, primarily used to seal any annular micro-seepage channels that may exist after construction and to provide fundamental isolation protection for the entire layered system. The internal layered sealing module provides a repeatable and precisely adjustable seal. Its setting pressure can be dynamically calculated and applied according to the specific requirements of each pumping test (such as the target aquifer depth and hydrostatic pressure), thus providing an active, high-pressure seal during pumping tests to ensure the strict independence of the pumping chamber. The external seal provides a stable working boundary for the internal sealing, while the internal sealing, through its adjustability, compensates for any shortcomings of the external seal. The two modules are spatially superimposed and functionally complementary, together forming a redundant and reliable layered isolation system.

[0128] Layered pumping and monitoring module: Pumping operations are performed in an independent "pumping chamber" created by the internal layered isolation module, and dynamic water level data of the pumping layer and its adjacent layers are collected synchronously and in real time.

[0129] Composition and working principle:

[0130] (1) Water pump: A submersible electric pump is used and is lowered into the target pumping chamber via a cable. In a preferred embodiment, the position of the water pump can be adjusted up and down inside the pumping chamber to optimize pumping efficiency.

[0131] (2) Water level monitoring unit: including submersible pressure water level sensors, etc. These sensors are connected to the ground data acquisition system through independent data lines in the cable and pipeline unit. Before being lowered into the well, each sensor is pre-positioned and fixed on the pipe string so that it is accurately aligned with the corresponding perforated pipe section of each target aquifer after being finally lowered into place. The cable and pipeline unit is an integrated bundle containing a pump power cable, a packer air supply line, and multiple sensor data lines. When the internal layered packer module is set and a pumping chamber is formed for a certain aquifer, the sensors located in the chamber monitor the water level of the pumping layer, while other sensors located outside the chamber (i.e., outside the upper and lower packers) continuously monitor the water level dynamics of the non-pumping aquifer through the filter holes of the corresponding perforated pipe section. The monitoring in the observation well adopts an independent monitoring device with a similar principle; all sensors are synchronously triggered and sampled through the same ground data acquisition system, with a sampling frequency of not less than 1 Hz, and GPS timing is used to ensure that the timestamps are consistent.

[0132] (3) Cable and line unit: This includes load-bearing cables, signal lines for transmitting data, and gas lines for supplying gas to the packer. These cables are usually bundled together and run downhole with the equipment.

[0133] Working principle and process: After the pumping starts, the pumping pump will extract water from the target aquifer, causing the water level in that layer to drop.

[0134] The stratified pumping and monitoring module includes a synchronous monitoring submodule, which performs the following functions:

[0135] a. Observe the water level changes in adjacent aquifers outside the chamber isolated by the upper and lower packers within this pumping well. b. Observe the water level changes in the corresponding aquifers in nearby observation wells.

[0136] All water level data is transmitted in real time to the ground data acquisition system via data cables. The module's pump operates within an independent chamber created by the internal layered isolation module. Its monitoring unit utilizes the perforated pipe section of the wellbore structure module to sense the actual pressure changes in each aquifer.

[0137] The synchronous monitoring submodule constructs a two-dimensional distributed verification network of "wellbore-stratum". When pumping water to a target layer (Ai), the system not only acquires the drawdown data of this layer, but more importantly, it acquires it synchronously.

[0138] 1. Water level change data (Δh_i-1, Δh_i+1) of adjacent non-pumping layers (Ai-1, Ai+1) within this well.

[0139] 2. Water level change data (Δh_i') of the corresponding layer (Ai') in the observation well.

[0140] By analyzing whether (Δh_i-1, Δh_i+1) approaches zero, the isolation effectiveness of the dual-sealing structure with internal and external synergy can be directly and quantitatively verified online. By comparing Δh_i and Δh_i', hydrogeological parameters can be solved more accurately using porous pumping theory.

[0141] Traditional stratified pumping can only "assume" that the water-stopping effect is effective, and the data quality is questionable. This invention, through the design of a monitoring network, synchronizes and digitizes the verification of the water-stopping effect with the acquisition of hydrological parameters, upgrading the "pumping test" into an integrated "pumping-verification-observation" test, thus solving the long-standing industry problem of the inability to verify the water-stopping effect in real time.

[0142] The working process of the hydrogeological exploration borehole stratified pumping control system in this embodiment is as follows:

[0143] 1. Geological Analysis and Design: Based on geological and geophysical data, analyze and determine the spatial distribution of the main aquifers and relative impermeable layers.

[0144] 2. Constructing the well structure and primary water sealing: Drilling and casing installation are carried out according to the design, and water-swellable sealing material is installed on the outside of the solid pipe at the location of the relative water-proof layer to complete the external layered water sealing.

[0145] 3. Install the internal layered packer and monitoring system: Lower the string of packers, which is connected to the water pump, monitoring sensors and inflatable packers, into the well to the predetermined depth.

[0146] 4. Setting and Verification: Inflate the packer to the calculated pressure to set it, forming a "pumping chamber". Observe the pressure to verify the structure's sealing performance.

[0147] 5. Layered pumping and synchronous monitoring: Start the water pump to conduct a pumping test. At the same time, automatically record the water volume and water level of the pumping layer, as well as the water level changes of adjacent layers and all layers in the observation well.

[0148] 6. Data calculation and model establishment: Based on pumping test data, calculate the precise hydrogeological parameters of each aquifer.

[0149] This embodiment forms a complete technical solution through the deep coupling and collaborative work of the above four modules in terms of function and structure, thereby solving a series of technical problems such as low efficiency, high cost and poor accuracy of traditional methods.

[0150] As an application example of this invention, referring to a hydrological supplementary exploration project in a mining area, the borehole structure design is as follows: In the first stage, a Φ444mm drill bit is used to drill to the top boundary of the target aquifer, and a Φ339.7mm surface casing is installed and cemented. In the second stage, a Φ241mm drill bit is used to enlarge the borehole to below all target aquifers, and a "stepped diameter" casing string is installed: in the upper main aquifer distribution section (equipment working section), a combination of solid and slotted pipes of Φ244.5mm and Φ177.8mm is installed, with the slotted pipe aligned with the aquifer, and the solid pipe wrapped with water-swellable tape and aligned with the aquitard; below this section, a Φ177.8mm solid pipe is directly installed to the final borehole. This structure effectively reduces the borehole diameter and casing usage in deep well sections while ensuring installation space for multi-layer pumping and monitoring equipment.

[0151] Example 2

[0152] This embodiment discloses a method for controlling stratified pumping in hydrogeological exploration boreholes. (See attached document) Figure 4 This includes the following steps:

[0153] S1. Geological Data Analysis and Layered Model Construction: Collect and analyze geological and geophysical data of the exploration area, identify and delineate multiple main aquifers and relatively impermeable layers below the top and bottom plates of the target coal seam, and construct a preliminary hydrogeological layered model.

[0154] In this invention, the hydrogeological stratification model specifically refers to a three-dimensional structure-attribute model, which consists of a series of discrete, spatially continuous geological horizons and their assigned hydrogeological attributes (such as the labels "aquifer" or "impermeable layer").

[0155] The model can be formally defined as a quintuple G = (H, A, T, P, R).

[0156] H (Horizons): A set of ordered stratigraphic horizons {H1, H2, ..., Hn}. Each horizon Hi is a function that maps two-dimensional planar coordinates (x, y) to elevation depth z: z = Hi(x, y). These horizons divide the subsurface space vertically into n-1 layers; (Attributes): A set of attributes assigned to each layer Li (between Hi and Hi+1), with the core attribute being Type(Li) ∈ {Aquifer, Aquitard}, i.e., "aquifer" or "relatively impermeable"; T (Thickness): The thickness field of each layer, T_i(x, y) = H_{i+1}(x, y) - H_i(x, y).

[0157] P (Properties): Hydrogeological parameters (such as permeability coefficient K) for each stratigraphic unit. In the initial model, empirical values ​​can be assigned based on Type, and these values ​​are updated to precise values ​​through the S5 step after pumping tests. R (Region): The effective three-dimensional spatial extent of the model.

[0158] This step forms the foundation for all subsequent work and aims to establish a precise understanding of the downhole geological structure. First, the system collects core records, geological columnar sections, and geophysical logging data (such as resistivity, spontaneous potential, sonic logging, and density logging) from existing boreholes within the exploration area. Through comprehensive analysis of this data, lithological patterns are identified, with a focus on identifying relatively aquitards in sections with stable thickness and dense lithology (such as mudstone and silty mudstone), and in sections with well-developed pores and fractures (such as sandstone and conglomerate) as aquifers.

[0159] This invention constructs a discretized, attributed three-dimensional structural model. This model is the sole digital basis for subsequent "stepped diameter" wellbore structure design, precise determination of internal and external water stop positions (S2), and calculation of packer setting depth (S3), transforming geological knowledge into executable engineering design instructions.

[0160] Step S1 employs a "multi-source data fusion and lithology-physical property correlation analysis" method. Specifically, it integrates borehole core logging, conventional logging (such as natural gamma ray and resistivity), and salinization or flow logging data to establish logging response identification criteria (e.g., high natural gamma ray values) for key aquitards (such as mudstone and silty mudstone). Through inter-well comparisons, the continuity and thickness variations of relative aquitards are delineated in three-dimensional space, thereby constructing a reliable structural model suitable for engineering design.

[0161] The process of constructing the hierarchical model G is as follows:

[0162] (1) Generation of lithological profiles from a single well (data fusion and feature extraction)

[0163] For each borehole, the input vector includes:

[0164] Core logging data: Lithology_Log(z), a function of depth z, with values ​​being discrete lithology codes (e.g., 1-mudstone, 2-sandstone, etc.).

[0165] Geophysical logging curves: GR(z) (natural gamma), RES(z) (resistivity), DEN(z) (density), etc.

[0166] Auxiliary logging data: SALT(z) (saltification logging tracer concentration) and FLOW(z) (flow logging) are used to verify the location of aquifers.

[0167] Construct a lithology classification model. Taking supervised learning as an example:

[0168] Training phase: In the core section, [GR(z), RES(z), DEN(z), ...] are used as features and Lithology_Log(z) is used as labels to train a classifier (such as random forest or support vector machine).

[0169] Prediction phase: The classifier is applied to the logging curves of all boreholes (including those without coring) to generate a continuous, high-resolution “predicted lithology profile” Pred_Lith(z).

[0170] (2) Identification and division of key hydrogeological units

[0171] Based on regional hydrogeological patterns, a judgment rule "Rule()" is defined. For example:

[0172] Aquitard (relative waterproof layer):

[0173] Rule_Aquitard = (Pred_Lith(z) = "mudstone") & (Thickness >= 5m). That is, a continuous mudstone section with a thickness greater than 5 meters.

[0174] Aquifer:

[0175] Rule_Aquifer = (Pred_Lith(z) ∈ {“sandstone”,“conglomerate”}) & (existence of FLOW(z) anomaly or SALT(z) dilution).

[0176] These rules are applied to scan the Pred_Lith(z) profile of each borehole to identify all Aquitard and Aquifer segments that meet the conditions, and their top and bottom depths (z_top, z_bottom) are recorded.

[0177] (3) Inter-well correlation and three-dimensional stratigraphic plane construction (model generation)

[0178] Layer numbering and tracking: Aquitards (such as M1, M2) and main Aquifers identified in each borehole that may be in the same region are numbered and compared.

[0179] Spatial interpolation: For the top (or bottom) surface of the k-th layer, collect control points (x_i, y_i, z_{i,k}) of that surface from all boreholes. Using geostatistical Kriging interpolation, generate a surface function H_k(x, y) continuously distributed across the entire area for that layer. Kriging not only provides estimates but also estimates of variance, which can be used to assess model uncertainty.

[0180] Model assembly: Arrange all layer planes {H_k} in order, and assign the Type attribute to each layer unit L_k (between H_k and H_{k+1}) according to its properties at the borehole (Aquifer / Aquitard), finally forming the complete G = (H, A, T, P, R).

[0181] (4) Model Output and Application

[0182] The final output hierarchical model G serves as the input for all subsequent steps. In S2, the design software reads G:

[0183] Determine the layer position for Type==Aquifer (requires a perforated tube).

[0184] Determine the location of the section with Type==Aquitard (solid pipes need to be installed and water stopped).

[0185] Based on the top and bottom depth ranges of all target Aquifers and the equipment dimensions, the depth range of the "equipment working section" and the optimal "stepped diameter change" scheme are determined through optimization algorithms.

[0186] In step S1, this invention discloses a complete and detailed technical chain from raw data to a quantifiable engineering design model. Through a data-driven lithology identification model and spatial statistical interpolation algorithm, a digital, three-dimensional structural model with attribute labels is constructed. This model is the intelligent core that enables the realization and optimization of all subsequent innovative steps of this invention (collaborative design, precise water stoppage, and stratified monitoring), demonstrating a significant advancement from "experience-based exploration" to "digital precision exploration."

[0187] Specific Implementation: For example, in a coal mining area, the goal might be to identify the aquifer system within approximately 150 meters above the roof of the main coal seam. By comparing and analyzing the lithology and logging curves of several preliminary exploration boreholes, two relatively stable mudstone sections can be identified above the coal seam roof. The lower mudstone section is named the "first relative aquifer," and the upper one is named the "second relative aquifer." These two aquifers divide the aquifer system above the coal seam roof into the "first aquifer section," "second aquifer section," and "third aquifer section" from top to bottom. By statistically analyzing the thickness and depth of these sections in multiple boreholes, a preliminary, quantitative hydrogeological stratification model can be constructed in three-dimensional space, clarifying the spatial distribution relationship of each stratum.

[0188] The stratified model obtained in this step is the sole basis for designing the wellbore structure and water-stopping scheme in step S2. The quality of the model directly determines whether subsequent drilling can successfully achieve effective stratification.

[0189] S2. Collaborative Wellbore Structure and Water-Stopping Scheme Design: Based on the aforementioned hydrogeological stratification model, design the wellbore structure for drilling, determine the depth of the surface casing to isolate shallow aquifers, and design the target section to use a combination of casings of the same diameter, that is, arrange solid pipes at the aquitard position and set external layered water-stopping materials on the outside of them, and arrange perforated pipes at the aquifer position.

[0190] The design of the collaborative wellbore structure and water-stopping scheme is based on the S1 model and applies the "cost-optimal design method under pump chamber constraints" to calculate and determine the optimal "stepped diameter change" scheme and the installation position and amount of external water-stopping material.

[0191] Wellbore Structure Design: Drilling is typically carried out in two stages. The first stage (often referred to as "first stage") uses a larger diameter drill bit (e.g., Φ444mm or Φ393mm) to drill below the top boundary of the main target aquifer and runs in surface casing (e.g., Φ339.7mm or Φ377mm), followed by cementing to permanently isolate the shallow aquifer. The second stage (often referred to as "second stage") first uses a smaller diameter drill bit (e.g., Φ98mm) to core drill to the final hole, performing detailed logging to verify and correct the S1 model. Then, a medium diameter drill bit (e.g., Φ241mm) is used to enlarge the hole to the final hole.

[0192] Same-diameter casing assembly and water-stopping scheme: In the second stage, a casing string of the same diameter (e.g., Φ177.8mm) is run throughout the entire borehole. Solid casing (impermeable casing) is installed at the location corresponding to the aquifer in the S1 model along the borehole trajectory; perforated casing (filter casing) is installed at the location corresponding to the aquifer. Simultaneously, water-swellable rubber or other water-stopping materials are pre-wrapped or installed on the outside of the solid casing section located at the relative aquifer. For example, 3-meter-long water-swellable tape is wrapped around the top and bottom ends of the solid casing corresponding to each planned aquifer segment. This design completes the construction of the first (external) water-stopping structure during the well completion stage.

[0193] In this embodiment, the pump is designed to be placed in the upper part of the pumping chamber corresponding to the target aquifer, forming a "pump chamber section". The well diameter of this section can be slightly larger to accommodate the pump body, while the lower well section can use a casing with a smaller diameter, thus achieving structural optimization and cost savings.

[0194] S3. Construction combining internal and external layers: Drilling and casing installation are carried out according to the design of S2, and external layered water sealing is implemented; then, an inflatable packer controlled by a surface gas source is inserted into the well to set at the upper and lower water-resistant layers of the target pumping section, forming an internal layered seal, which together constitutes the structure. This step is the key to achieving reliable layering. External water sealing and internal sealing are implemented in sequence.

[0195] External layered water-stopping construction: Drilling, casing (including casing strings with water-stopping material) and annulus filling operations are carried out strictly in accordance with the S2 design. After the casing is installed, the water-stopping material begins to expand upon contact with the formation water. After a certain period of time (e.g., 24-72 hours), a primary seal is formed between the casing and the well wall.

[0196] Internal layered packer construction: Subsequently, a surface-controlled pneumatic expansion packer system is lowered into the well. This system typically includes at least one set (upper and lower) of packers, a central tube connecting them, a pump, a water level sensor, and integrated gas lines and cables. It is lowered to the target pumping section using drill pipe or tubing, with the upper packer positioned above the top boundary of the section within the relative impermeable layer, and the lower packer positioned below the bottom boundary of the section within the relative impermeable layer.

[0197] Setting and Verification: Compressed gas is injected into the inner cavity of the packer's rubber sleeve via a high-pressure gas source (such as a nitrogen cylinder) and a pressure regulating valve through a gas pipeline. The setting pressure needs to be precisely calculated; the theoretical formula is: Setting pressure (MPa) = [Center depth of packer (m) - Static water level depth (m)] / 100 + Additional pressure (0.5~1.0 MPa). After pressurization, the packer's rubber sleeve expands and tightly adheres to the inner wall of the casing inserted at S2, forming a secondary seal. The two packers then form an "independent pumping chamber" hydraulically isolated from the upper and lower sections. Pressure stabilization and observation (e.g., 2 hours) are required to confirm no pressure drop before verifying the effectiveness of the "structure." This is a major innovation of this method: the external waterstop provides basic isolation, while the internal packer achieves precise, adjustable, and reversible sealing. The synergy of these two methods completely solves the problems of poor sealing reliability and easy failure in traditional single waterstop methods, laying a solid foundation for obtaining high-precision hydrogeological parameters.

[0198] S4. Layered Pumping and Synchronous Monitoring: Pumping tests are conducted in an independent pumping chamber isolated by S3. Simultaneously, water level monitoring equipment is used to monitor the dynamic changes in water level in the pumping section, adjacent non-pumping sections within the pumping hole, and corresponding sections of surrounding observation holes. Pumping tests are carried out in the verified and reliable sealed "independent pumping chamber," and the core "synchronous monitoring" is implemented.

[0199] Stratified pumping: Start the submersible pump installed in the chamber to pump water at a certain flow rate. The pump position is preferably adjustable to find the optimal water inlet point.

[0200] Synchronous monitoring is achieved through multiple independent water level sensors deployed at different aquifer levels within the pumping wells and observation wells. All sensors are connected to the same ground-based data acquisition and processing system via communication lines. During pumping, the synchronous monitoring system performs the following operations simultaneously:

[0201] 1. Monitor the dynamic water level changes and pumping volume within this pumping chamber.

[0202] 2. Monitor the water level dynamics in other non-pumping water-bearing sections within this borehole (through their corresponding perforated pipes).

[0203] 3. Monitor the water level dynamics in adjacent observation wells corresponding to the pumping layer.

[0204] For example, when pumping water from the second aquifer section of a test well, in addition to monitoring the water level in that section, the water levels in the first and third aquifer sections of the same well are also monitored simultaneously, as well as the water level in the second aquifer section of a nearby observation well. All this data is transmitted in real time to a ground data acquisition unit via cable.

[0205] Synchronous monitoring constitutes a distributed hydrological monitoring network. When pumping water into a certain aquifer in a test well (such as Special Water 5), not only is the water level of each layer in this well monitored, but the water level response of the corresponding aquifer in the adjacent observation well (such as Special Water 4) is also monitored simultaneously. This allows for the acquisition of dynamic water level data from multiple wells and layers at once, which greatly improves the efficiency of hydrogeological testing and the accuracy of model calibration.

[0206] In this stratified pumping and synchronous monitoring process, the data acquisition system operates according to a predetermined timing control logic, ensuring that the timestamps of all data streams, such as pumping flow records, dynamic water level of the current layer, water level of adjacent layers, and water level of observation wells, are strictly synchronized, laying the foundation for subsequent accurate calculations.

[0207] S5. Data Integration and Hydrogeological Parameter Calculation: Based on the pumping volume and synchronous water level monitoring data obtained in S4, the hydrogeological parameters of each aquifer are calculated, and finally a high-precision model that can truly reflect the characteristics of the groundwater flow field is formed.

[0208] This step is based on the theoretical model of "multi-layer aquifer system". It uses multi-source synchronous drawdown data obtained by S4 and adopts a numerical inversion algorithm to simultaneously fit the water level response curves of pumping wells and each observation well. This allows for the one-time calculation of the hydrogeological parameters of each aquifer and the overflow coefficient between them, avoiding the isolation and cumulative errors of traditional layered test parameter calculation.

[0209] By collecting all time-series data obtained in S4, including pumping flow rate Q(t), drawdown s(t) of the pumping layer, and water level change data of each observation layer and well, and using this clean and reliable data, the key hydrogeological parameters of the target aquifer, such as permeability coefficient K, hydraulic conductivity T, and storage coefficient S, are obtained by substituting them into the corresponding hydrogeological calculation formulas (such as the Theis formula, Jacob formula, etc.) or numerical simulation software. Based on these accurate parameters, the preliminary hydrogeological model constructed in S1 is corrected, improved, and quantified, ultimately forming a high-precision model that can truly reflect the characteristics of the groundwater flow field.

[0210] This step directly depends on the successful implementation of S3 and S4, thus ensuring the accuracy of the final model and parameters.

[0211] This invention forms a complete hydrogeological fine exploration process through the organic connection and closed-loop feedback of the above five steps: starting from geological understanding (S1), carrying out forward-looking design (S2), constructing a reliable downhole experimental environment through innovative construction (S3), performing multi-dimensional data acquisition (S4), and finally producing high-value results (S5).

[0212] This invention, by constructing an integrated technical system encompassing "well body structure - external layered water sealing - internal layered isolation - collaborative monitoring," creatively proposes a "stepped variable diameter structure" well body design and a core scheme combining internal and external elements, supplemented by a "synchronized pumping and observation" monitoring mode. The synergistic application of this series of technologies systematically and thoroughly solves the key technical problems that have long plagued traditional hydrogeological exploration borehole layered pumping techniques, such as low construction efficiency, high economic costs, poor water sealing reliability, limited accuracy of obtained parameters, and insufficient borehole utilization. This invention not only provides a complete and reliable technical solution but also promotes the development of coal mine hydrogeological exploration towards refinement, efficiency, and low cost, demonstrating significant practicality and outstanding substantive characteristics, and meeting the inventiveness requirements of patent law.

[0213] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method for controlling stratified pumping in hydrogeological exploration wells, characterized in that, Includes the following steps: S1. Collect and integrate borehole core data, geophysical logging data, and hydrological logging data from the exploration area; based on multi-source data fusion and lithology-physical property correlation analysis, establish identification rules to accurately delineate multiple main aquifers and relative impermeable layers in the vertical direction; and construct a three-dimensional digital hydrogeological stratification model containing stratigraphic planes, properties, thicknesses, and parameter fields through inter-well comparison and spatial interpolation. S2. Based on the three-dimensional digital hydrogeological stratification model described in S1, the well structure is optimized with the size of the pumping equipment as a constraint: the depth of the surface casing used to isolate the shallow main aquifer is determined; and a stepped diameter casing combination is designed for the target section. In this case, solid pipe sections are arranged at the relative aquifer positions determined by the model, and water-swellable sealing materials are pre-set on the outside of the solid pipe sections. Perforated pipe sections are arranged at the main aquifer positions to ensure that a pump chamber section for accommodating the pump is formed in the upper main aquifer section. S3. Drilling, casing installation, and cementing operations are carried out according to the design in S2, causing the water-swellable sealing material to expand in the formation water and form a primary long-term seal. Subsequently, an air-expanding packer string controlled by the surface gas source control unit is lowered into the well and positioned at the upper and lower relative water-resistant layers corresponding to the target pumping section. The setting pressure is dynamically calculated and applied based on the downhole hydrostatic pressure to set the air-expanding packer string, forming a secondary reversible seal. The external primary long-term seal and the internal reversible seal together constitute a dual sealing structure with internal and external coordination, forming an independent pumping chamber hydraulically isolated from the upper and lower relative water-resistant layers. S4. Conduct a pumping test in the independent pumping chamber formed in S3; at the same time, use water level sensors pre-installed in the main aquifer sections of the pumping hole to synchronously monitor the drawdown of the pumping section and the water level changes in adjacent non-pumping sections in the pumping hole to verify the isolation effectiveness of the double sealing structure, and use water level sensors in the corresponding layers in the observation holes to monitor the water level response of the surrounding observation holes. S5. Integrate the synchronous time series data obtained in S4, including pumping volume, drawdown of the current layer, water level changes of adjacent layers, and water level changes of observation wells; use the theoretical model of the multi-layer aquifer system and numerical inversion algorithm to simultaneously fit the water level response data, calculate the permeability coefficient, storage coefficient, and interlayer overflow coefficient of each major aquifer, and update the parameter field in the digital layered model constructed in S1 to form a high-precision hydrogeological model.

2. The method according to claim 1, characterized in that, In step S1, the three-dimensional digital hydrogeological stratification model includes: Using borehole core logging data as training labels and geophysical logging curves as features, a lithology classification model is trained to generate predicted lithology profiles of boreholes. Based on the preset rules for identifying the main aquifers and relative impermeable layers, the predicted lithological profile is scanned to identify the top and bottom depths of each main aquifer and relative impermeable layer. By using inter-well comparison and geostatistical spatial interpolation methods, the top and bottom surfaces of the same relative impermeable layer or main aquifer in each borehole are connected to generate a three-dimensional stratigraphic plane that is continuously distributed throughout the area, thereby constructing a structured stratigraphic model consisting of stratigraphic plane sequence, hydrogeological properties, thickness field and parameter field. The lithology classification model uses a bidirectional LSTM network based on an attention mechanism. Its input is a multi-channel well logging curve time series, and its output is a lithology probability distribution. The network loss function is: L = α·L_ce + β·L_smooth. Where: L_ce is the cross-entropy loss; L_smooth is the smoothing loss of lithology labels at adjacent depths to avoid frequent lithology jumps; α and β are weighting coefficients, determined through grid search.

3. The method according to claim 2, characterized in that, The three-dimensional digital hydrogeological stratification model constructed in step S1 is defined as a structure-attribute model G = (H, A, T, P, R), where: H is an ordered set of stratigraphic horizon functions that map planar coordinates to elevation and depth; A is the hydrogeological attribute of each stratum unit divided based on the horizon, with values ​​of "main aquifer" or "relative impermeable layer"; T is the thickness field of each stratum unit; P is the hydrogeological parameter field of each stratum unit; and R is the effective spatial range of the model.

4. The method according to claim 1, characterized in that, Steps S3 and S4 are repeated sequentially for multiple main aquifers in a single well to achieve a stratified pumping test of multiple main aquifers in one well.

5. The method according to claim 1 or 2, characterized in that, In step S3, the dynamic calculation and application of the setting pressure specifically involves: according to the formula P_setting = (H_packer - H_static water level) / 100 + P 附加 Calculate the theoretical setting pressure, where H_packer and H_static water level are in meters, and P_setting and P_additional are in megapascals. 附加 Additional pressure used to overcome resistance and ensure a seal; The ground gas source control unit implements a step-by-step pressure stabilization-feedback adjustment strategy: first, apply pressure to 80% of the theoretical pressure and observe the pressure stabilization. If the pressure does not decrease, start the PID control algorithm to gradually increase the pressure to the theoretical pressure value, and continuously adjust it throughout the pressure stabilization process to maintain pressure stability. The inflatable packer includes a central tube, a rubber sleeve fitted outside the central tube, and an air inlet channel connecting the central tube to the ground air source control unit; setting is achieved by filling the air inlet channel with high-pressure gas to cause the rubber sleeve to expand radially; unsealing is achieved by releasing high-pressure gas to cause the rubber sleeve to contract.

6. The method according to claim 1, characterized in that, The synchronous monitoring described in step S4 is achieved in the following way: before the air-expanded packer string is lowered, multiple water level monitoring units are pre-positioned and fixed on the pipe string so that they are finally aligned with their respective main aquifer sections; after the packer is set to form an independent pumping chamber, the water level monitoring unit located in the chamber monitors the water level of the pumping layer, while the water level monitoring units located above and below the chamber and aligned with other main aquifers monitor the water level dynamics of the corresponding non-pumping layers.

7. A stratified pumping control system for hydrogeological exploration wells, used to execute the method as described in claim 5, characterized in that, include: The wellbore structure module is used to construct a borehole structure that can reach multiple target main aquifers. It includes a surface casing unit for isolating shallow main aquifers and a target layer casing unit for penetrating the target main aquifer and the relative aquitard. The target layer casing unit includes a solid pipe section set at the position of the relative aquitard and a perforated pipe section set at the position of the main aquifer, which are based on a three-dimensional digital hydrogeological stratification model. The external layered water-stopping module, which cooperates with the solid pipe section of the well body structure module, includes a water-swellable water-stopping material placed on the outside of the solid pipe section, used to form a long-term seal between the borehole wall and the casing. The internal layered packer module includes at least one set of inflatable packers that can be lowered into the well via drill pipe, and a surface gas source control unit that provides a pressure source for the packers and can dynamically control the setting pressure. The packers are used to set at the upper and lower relative aquitard positions of the target pumping section. The stratified pumping and monitoring module includes a pump installed in an independent pumping chamber formed by upper and lower packers, a water level monitoring unit for monitoring the water level in the pumping section and adjacent non-pumping sections, and a cable and pipeline unit connecting the ground and downhole equipment. The external layered water-stopping module and the internal layered sealing module together form a double sealing structure that works in tandem to ensure effective isolation of each major aquifer during the pumping test. The well structure module also includes a pump chamber section located in the upper target major aquifer, and the pump of the layered pumping and monitoring module is located in this pump chamber section.

8. The system according to claim 7, characterized in that, The target layer casing unit of the wellbore structure module adopts a stepped variable diameter structure, that is, the upper well section where the target main aquifer is located uses a casing assembly with a first diameter, and the lower well section below the upper well section uses a casing with a second diameter smaller than the first diameter.

9. The system according to claim 7, characterized in that, The inflatable packer in the internal layered packer module includes a central tube, a rubber sleeve fitted outside the central tube, upper and lower connectors, and an air inlet channel.

10. The system according to claim 7, characterized in that, The pump of the stratified pumping and monitoring module is located in the pump chamber section, so that the lower well section is no longer limited by the size of the pumping equipment, thereby allowing the use of smaller diameter casing and well structure; the position of the pump can be adjusted up and down along the pumping chamber to adapt to the water output characteristics of different main aquifers.

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