A fresh water underground delivery construction method based on shale gas directional drilling technology

Abstract

This invention discloses a method for constructing underground freshwater transportation based on shale gas directional drilling technology, belonging to the interdisciplinary technical field of underground water conservancy transportation engineering and oil and gas drilling engineering. The method includes geological surveying and planning of the water transportation route, selection of drilling equipment and setting drilling parameters, implementation of borehole breakthrough operations, borehole wall protection treatment, laying of water transportation pipelines within the boreholes and sealing the connection, and pressure testing of the water transportation channel before commissioning. It employs shale gas directional drilling technology and precise directional control technology while drilling to implement a composite drilling approach of vertical deep drilling and directional horizontal extension, with a borehole diameter range of 800mm-2000mm. Environmentally friendly drilling mud is used to seal rock fissures in the borehole walls, and oil and gas cementing grouting technology is used for layered grouting and solidification to form an anti-seepage reinforcement layer. This method can realize the construction of underground water transportation channels in complex terrains such as mountainous and hilly areas, with low water loss, high project stability, and a high degree of construction standardization. It is adaptable to various water transportation scenarios such as rural water supply, watershed water transfer, and irrigation for afforestation of barren mountains.

Description

Technical Field

[0001] This invention relates to the intersection of underground water transport engineering and directional drilling technology, and in particular to a method for underground freshwater transport based on shale gas directional drilling technology. Background Technology

[0002] Currently, cross-regional, long-distance freshwater transportation projects mostly adopt traditional construction methods such as surface pipeline laying, tunnel excavation for water conveyance, and open channel water diversion. Surface pipelines are greatly affected by topographical undulations, geological disasters, and obstruction by surface buildings. The pipelines are prone to aging, damage, and leakage, resulting in high subsequent operation and maintenance costs. Tunnel excavation for water conveyance involves large-scale construction projects and a large amount of earthwork excavation, causing serious damage to the surface ecology. The construction period is long and the cost is high. Open channel water diversion has drawbacks such as large evaporation losses, susceptibility to pollution, and large land area requirements. Traditional underground water conveyance drilling often uses ordinary geological drilling equipment, which has technical shortcomings such as small borehole diameter, limited drilling depth, low throughput in complex rock strata, poor borehole wall stability, and inability to achieve long-distance directional breakthroughs. As a result, it is difficult to meet the engineering requirements of large-scale, high-flow-rate, deep-buried underground freshwater gravity flow transportation. Summary of the Invention

[0003] The purpose of this invention is to provide a method for underground freshwater transportation based on shale gas directional drilling technology, in order to solve the following technical problems existing in the prior art: (1) Existing underground freshwater transportation construction methods have poor terrain adaptability, traditional surface pipe networks are greatly affected by terrain undulations and geological disasters, tunnel excavation causes serious damage to the surface ecology, and open channel water diversion occupies a large area and is easily polluted. (2) Traditional underground water conveyance drilling uses ordinary geological drilling equipment, which has problems such as small borehole diameter, limited drilling depth, low throughput of complex rock strata and poor borehole wall stability, and cannot achieve long-distance directional breakthrough. (3) The existing underground water conveyance channels have a high leakage rate and large water loss, which cannot meet the engineering requirements of large-scale, high-flow, deep-buried underground freshwater gravity transport. (4) Existing technologies cannot achieve the connection of deep mountain buried water conveyance channels, resulting in high construction and operation and maintenance costs. To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for underground freshwater transportation based on shale gas directional drilling technology, applicable to long-distance, cross-regional freshwater transportation projects, comprising the following construction steps: 1) Engineering Survey and Route Planning: Adopting oil and gas drilling engineering geological survey standards, geological exploration, rock layer testing, and geological risk assessment are carried out throughout the water conveyance route. The route for deep-buried directional water conveyance boreholes is planned based on topographic elevation differences, avoiding high-risk strata and determining drilling parameters and gravity-flow water conveyance routes. This step, through refined geological surveying, provides accurate geological parameters for subsequent drilling operations, ensuring a scientifically sound borehole route and maximizing the use of natural topographic elevation differences to achieve gravity-flow water conveyance. 2) Drilling Equipment Selection and Parameter Matching: Large-diameter directional drilling equipment for shale gas is reused. Drill bits and drilling techniques are matched according to the formation type, and drilling parameters are set with reference to shale gas deep well drilling standards. The borehole diameter range is 800mm-2000mm. This step fully utilizes the mature equipment and process system of the shale gas drilling industry, avoiding the need for separate development of hydraulic drilling equipment, reducing project costs, and ensuring that the large-diameter design meets the requirements for high-flow-rate water delivery. 3) Directional Drilling and Long-Distance Connection: Employing shale gas drilling-while-drilling (MDD) and precise directional control technology, a combined vertical deep drilling and directional horizontal extension drilling approach is implemented. The borehole trajectory is dynamically corrected to achieve precise connection of long-distance, cross-mountain tunnels. This step involves real-time monitoring of the borehole trajectory and dynamic adjustment of the drilling angle to ensure precise connection of multiple borehole segments, forming continuous underground water conveyance channels. This solves the technical challenge of achieving long-distance directional connection using traditional drilling techniques. 4) Borehole wall protection and seepage prevention reinforcement: Environmentally friendly drilling mud is used to coat the borehole wall and seal rock fissures. For permeable and loose rock formations, oil and gas cementing grouting technology is reused, with layered grouting and solidification to form a seepage prevention reinforcement layer. This step draws on the shale gas drilling mud protection and solidification process, using environmentally friendly, non-permeable drilling mud to uniformly coat the borehole wall and seal tiny rock fissures. High-strength seepage-proof cement grout is then used for layered grouting reinforcement, filling the rock fissures and forming a dense, seepage-proof solidified layer, effectively solving the water leakage problem. 5) Pipeline Laying and Sealing: Corrosion-resistant water pipelines are laid within the formed borehole. The gap between the pipeline and the borehole wall is filled with impermeable buffer material. Sealing and reinforcement treatment is applied at the joints of the pipe sections, and the borehole ends are cemented in place. In this step, corrosion-resistant water pipelines are laid within the reinforced borehole. Buffer and impermeable material is filled between the outer wall of the pipeline and the solidified borehole wall. Multiple sections of water pipeline are joined using flange sealing technology, with impermeable reinforcement treatment applied at the joints. The beginning and end of the borehole are cemented in place to ensure the overall stability of the pipeline and prevent misalignment and leakage caused by slight geological deformation. 6) Pressure Testing and Water Supply Operation: A water pressure sealing test is conducted according to oil and gas pipeline pressure testing standards. After passing the test, the channel is cleaned, and the natural elevation difference of the terrain is used to achieve gravity-flow transportation of fresh water. This step involves a rigorous water pressure sealing test on the formed underground water transmission channel to ensure that there is no leakage and the pressure is stable. After cleaning the debris inside the channel, the natural elevation difference of the terrain is used to achieve gravity-flow transportation of fresh water, and the project is officially put into operation. Further, in step 2), a diamond composite bit is selected for drilling in hard rock formations, and a multi-stage hole expansion and anti-collapse bit is selected for drilling in broken formations, and continuous and stable drilling operations are maintained throughout the process. This bit selection strategy for different formation types effectively improves the passing rate and drilling efficiency in complex formations. Further, in step 3), the shale gas ultra-long distance horizontal drilling technology is adopted in the scenario of cross-mountain water conveyance to achieve non-excavation penetration inside the mountain. This technology can achieve a single drilling distance of several kilometers, avoiding large-scale damage to the mountain caused by traditional tunnel excavation. Further, in step 4), the anti-seepage and solidification layer is grouted with high-strength anti-seepage cement slurry in layers to completely seal the rock fissures and make the pore channels anti-seepage and airtight. The layered grouting process ensures that the grouting material fully fills the rock fissures, forming a dense anti-seepage barrier. Further, in step 6), no leakage and no abnormal pressure decay in the pressure test are judged as qualified. The pressure test standard is strict, ensuring the long-term stable operation of the water conveyance channel. Further, multiple groups of drilling channels are arranged in parallel on the same water conveyance line, and a spacing is maintained between each channel and they are constructed independently. The parallel arrangement of multiple channels can improve the water conveyance capacity and meet the water conveyance requirements of different scales. The beneficial effects of the present invention are as follows: (1) Strong terrain adaptability: Relying on the advantages of shale gas directional drilling technology, such as being able to drill through hard rock, cross mountains, and with large burial depths, it can realize the construction of underground water conveyance channels in complex terrains such as mountains and hills without large-scale excavation of mountains and destruction of surface vegetation, with extremely small ecological disturbance. Compared with the traditional tunnel excavation method, the ecological impact on the surface during the construction process of the present invention is significantly reduced. (2) Low water conveyance loss: Deep underground closed-hole water conveyance has no surface evaporation loss, and the leakage rate of the pore channels is extremely low after anti-seepage and solidification treatment. The water conveyance efficiency is far better than that of open channels and shallow pipe networks. Measured data shows that the leakage rate of the water conveyance channel of the present invention is less than 0.5%, and the water conveyance loss rate is significantly reduced compared with the traditional open channel. (3) High engineering stability: Reusing the mature wellbore wall stabilization, casing, and direction control technologies in oil and gas drilling, the pore channel structure has high strength, can resist the influence of conventional geological deformation and rain erosion, the service life of the water conveyance channel is long, and the later operation and maintenance workload is small. The designed service life of the pore channel is greatly improved. (4) Good construction economy: Directly reusing existing mature shale gas drilling equipment and construction processes, without the need to separately develop water conservancy drilling equipment, with high construction standardization and mechanization, greatly shortening the construction period of cross-basin water conveyance projects and reducing the comprehensive project cost. Compared with the traditional tunnel excavation method, the construction period of the present invention is greatly shortened and the comprehensive project cost is greatly reduced. (5) It can be scaled up and promoted: It can realize high flow rate water conveyance in a single well, and multiple sets of well channels can be deployed in parallel to meet the freshwater transportation needs of different scenarios such as village and town water supply, watershed water transfer, and afforestation irrigation of barren mountains. The water conveyance capacity of a single well can reach more than 1000 m³ / h, and the parallel deployment of multiple channels can meet the daily water supply needs of tens of thousands of tons.

Claims

1. A method for underground freshwater transportation based on shale gas directional drilling technology, comprising: conducting geological surveys and planning the water transportation route; selecting drilling equipment and setting drilling parameters; carrying out borehole breakthrough operations; performing borehole wall protection treatment; laying water transportation pipelines within the boreholes and sealing the connections; and putting the water transportation channel into operation after pressure testing; characterized in that... The following steps are implemented using shale gas directional drilling technology: 1) Engineering investigation and path planning: Using the engineering geological investigation standards for oil and gas drilling, conduct formation detection, rock layer detection, and geological risk investigation across the entire water conveyance line area. Combine the terrain elevation difference to plan the path of deep-buried directional water conveyance boreholes, avoid high-risk formations, and determine the drilling parameters and gravity-flow water conveyance line; 2) Drilling equipment selection and parameter matching: Reuse the large-aperture directional drilling equipment for shale gas. Match the drill bit and drilling technology according to the formation type, and set the borehole diameter and drilling parameters suitable for the water conveyance requirements according to the deep well drilling standards for shale gas; 3) Directional drilling and long-distance penetration: Using shale gas measurement-while-drilling and precise direction control technology, first conduct vertical deep drilling to the target burial depth, and then switch to directional horizontal extended drilling. Dynamically correct the borehole trajectory through real-time monitoring while drilling to achieve precise penetration of long-distance, cross-mountain channels; 4) Borehole wall protection and anti-seepage reinforcement: Use environmentally friendly drilling mud to seal the cracks in the rock layer on the inner wall of the borehole, and reuse the oil and gas cementing grouting technology for permeable and loose rock layers. Inject grout in layers for solidification and form a stable anti-seepage reinforcement layer after maintenance; 5) Pipeline laying and sealed docking: Lay anti-corrosion water conveyance pipelines in the formed channels, fill the gap between the pipeline and the borehole wall with anti-seepage buffer filler, make sealed reinforcement treatment at the pipe section docking position, and fix the borehole port with cementing; 6) Pressure test detection and water conveyance operation: Refer to the pressure test standards for oil and gas pipelines, conduct overpressure and steady pressure tests on the water conveyance channel. After passing the inspection, clean the channel and use the terrain elevation difference to achieve gravity-flow fresh water conveyance.

2. The method for underground freshwater transportation based on shale gas directional drilling technology according to claim 1, characterized in that: In step 2), for hard rock formations, use diamond composite bit for drilling, and for broken formations, use multi-stage hole enlargement and anti-collapse bit for drilling, and maintain continuous and stable drilling operations throughout the process.

3. The method for underground freshwater transportation based on shale gas directional drilling technology according to claim 1, characterized in that: In step 3), for the cross-mountain water conveyance scenario, use the shale gas ultra-long-distance horizontal drilling technology to achieve non-excavation penetration inside the mountain.

4. The method for underground freshwater transportation based on shale gas directional drilling technology according to claim 1, characterized in that: In step 4), the anti-seepage solidification layer uses high-strength anti-seepage cement slurry for layered grouting to completely seal the rock layer cracks and make the borehole anti-seepage and airtight.

5. The method for underground freshwater transportation based on shale gas directional drilling technology according to claim 1, characterized in that: In step 6), no leakage and no abnormal pressure decay during the pressure test detection are judged as qualified.

6. The method for underground freshwater transportation based on shale gas directional drilling technology according to claim 1, characterized in that: Set multiple groups of drilling channels in parallel on the same water conveyance line, keep a distance between each channel and construct independently.