The construction of horizontal directional drilling crossing the pipeline is generally divided into two stages: the first stage is to drill the pilot hole as accurately as possible according to the design curve, and the second stage is to drill the pilot hole, enlarge the hole and expand the product pipeline (generally PE pipe, cable, casing and tubing) along the line.
1. 1 drilling pilot hole:
When crossing geological conditions, select appropriate drill bit and guide plate or downhole mud motor to start the mud pump arrangement, bury the drill, the drill bit rotates by thrust (or drives the drill bit to rotate by mud motor) to cut the stratum, move on, and adjust the drill bit and drilling direction to meet the actual position required by the design, so as to ensure the completed pilot hole curve until the completed pilot hole drill bit is unearthed at the predetermined position. Please refer to Figure 1: Drill a pilot hole.
The curve of the drilling rig installed at the underground excavation point of sidetracking is used as the guide line of the carefully designed buried point along the pre-reaming and back-dragging pipeline.
1.2 Pre-reaming and product pipeline recovery:
In general, when using a small drilling rig, it is necessary to use a large-diameter articulated drilling rig larger than 200 mm. When the pipe diameter of the product is larger than the pre-reaming and pre-sinking hole diameters of Dn350mm, it depends on the specific model and the geological conditions of the drilling rig.
The first reamer of the callback product line is connected to the pipeline, and then the callback operation is started. During callback, the product pipeline dragged by the rotary table of the drilling rig drives the drill pipe to rotate for drilling, but it does not rotate, and it is full of mud for drilling. Therefore, the product expands the drilling hole, and the mud around the pipeline lubricates the hole wall in a suspended state, which reduces the recovery and protection of the pipeline anticorrosive coating, and part of the pre-reaming eventually enters the drilling rig with a pipe diameter greater than 200mm, so that the anticorrosive coating will not be damaged. See Figure 2: Pre-reaming and Schematic Diagram: Callback? Line.
In the pilot drilling stage, the drilled hole is often smaller than the diameter, and the diameter of drill pipe decreases 1.3? 1.5 times, yes, it is necessary to enlarge the buried hole diameter at the initial stage of reamer excavation.
After the underground cave, the trailer, drill bit and reamer are pre-reamed, and the installation pipes are connected to the excavation point in turn until the buried pipes are pushed back to the point for reaming.
Characteristics of horizontal directional drilling construction:
2. 1 directional drilling crossing construction does not hinder traffic, does not destroy green space, vegetation, shops and hospitals, and does not affect the residents and working order of normal schools, thus solving the interference, destruction and adverse effects of traditional excavation construction on residents' lives. On the basis of traffic, environment and surrounding buildings,
2.2 the leap-forward development of modernization, through high-precision equipment, easy adjustment and long-distance transportation? The direction and buried depth of the pipeline fully meet the design requirements, and the buried depth of the underground pipeline is bypassed.
2.3 The depth of urban pipe network is generally as high as three meters across the river, and the depth under the river bed is generally as deep as 9- 18 meters. Therefore, whether to use horizontal directional drilling to cross the river will not have any impact on the surrounding environment, and will not destroy the landform and environment, which meets the requirements of environmental protection.
2.4 Horizontal directional drilling rig crossing construction, waterless and underwater operation, does not affect inland navigation, does not damage river dams and riverbed structures, and has few construction restrictions in major seasons, short construction period, few personnel, safe and reliable construction and high success rate.
2.5 Compared with other construction methods, the fast construction site can be flexibly adjusted, especially in urban construction. Become? Set, can give full play to their own advantages, construction, small area, low project cost, fast construction speed.
2.6 Rivers buried in the stratum below 9- 18MM have little oxygen and other corrosive substances, which play a natural role in anti-corrosion and heat preservation and ensure the long-term operation of pipelines.
Brief introduction of horizontal directional drilling system;
The structures and functions of various horizontal directional drilling systems, power systems, control systems, mud, drilling and auxiliary equipment are described as follows.
3. 1 Drilling operation and callback operation of the rig system across equipment, as well as drilling operation and callback operation of the main rig and rotary table rig placed on the frame are completed. The turntable is installed in the main engine of the drilling rig and connected to the front end of the drill pipe. By changing the steering and output speed and torque of the turntable, different working conditions can be met.
3.2 Power system: hydraulic power source and generator platform provide power, and electrical equipment and lighting system at the construction site provide high-pressure hydraulic oil.
3.3 Guidance system: The control system is controlled by a computer, which monitors and controls the specific position and other parameters of the drill bit underground, guides the correct drilling directional tools, and the system is controlled. At present, according to the design curve, two forms of control systems, mobile wireless drilling and wired drilling, are usually used.
3.4 Mud system: mud mixing tank, mud pump drilling rig, mud and slurry conveying pipeline.
3.5 Drilling and auxiliary equipment: all kinds of mechanical drilling machines are used for drilling and reaming. Drilling various geological drill pipes, drill bits, mud motors, reamers, milling cutters and other equipment. Auxiliary equipment includes buckles of various diameters, rotary joints and tractors.
Through the arrangement in the construction site
1。 Mainly horizontal directional drilling and burying. What is the floor area of the drilling rig next to it? Bigger smallest DD330 drilling rig? 30×30M, of course, according to the actual area? On-site, properly adjusted, the proportion of DD60 and DD -5 is very small.
2。 Excavate a 20×20M site as one side of the main point of the pipeline welding site, such as pre-reaming, and then return to the pipeline, where the drill pipe will be dragged to other equipment for installation, and the length is equal to the welding work of the trenchless point.
take for example
Across Dagusha, the well site layout is 9 months to 1998 to 10 in Tanggu, Tianjin. Our company completed the crossing of two 960m-long pipelines in only 45 days.
Welding site (only two in Dagusha)
Flow chart of horizontal directional drilling crossing construction
/A & gt；
& gt
Using horizontal directional drilling technology to cross rivers and other obstacles has been widely used in the world. The person in charge of the Association of Horizontal Directional Drilling Contractors said: In the bidding process, we should do as much information as possible for the project and put forward a complete and competitive quotation. Before construction, the contractor shall obtain the following information to ensure the smooth progress of future work, and complete the project construction under this condition. While providing all kinds of information before construction, the contractor shall ensure the safety in the construction process to reduce the damage to the surrounding environment. Go smoothly.
abstract
one
Horizontal directional drilling technology first appeared in the 1970s. The traditional directional drilling technology, which combines road drilling with oilfield development and utilization, has become a popular construction method, which can be used for the construction of various pipelines, electric power and cables for transporting oil, natural gas, petrochemical, water and sewage. It is not only suitable for the intersection of rivers and waterways, but also widely used in the construction of roads, railways, airports, coasts, islands, dense pipelines and clouds.
B, technical restrictions, alluvium
Directional drilling technology was first used in the coastal areas of the United States, and now coarse sand, gravel, moraine and rocks can be used to cross areas with complex geological conditions. The longest span building reaches 6000 feet with a diameter of 18 inch.
C. advantages
Practice has proved that the horizontal directional drilling crossing construction has the least impact on the environment. This technology also provides a pipeline with protective layer and the corresponding construction method to reduce the maintenance cost, but it will not affect the river flow and shorten the construction period, which is proved to be the most effective and the lowest cost.
D, construction technology and technology
1, pilot hole: a pilot hole along the horizontal direction of a predetermined section, drilled at a predetermined angle, including straight chain cutting and large radius arc. When drilling pilot holes, the contractor can choose to use a drill pipe with larger diameter (i.e. flushing pipe) to protect the guide rod. The flushing pipe can play a similar role as a catheter, and can also be a convenient guide rod and replacement drill. The direction of the pilot hole is controlled by the controller at the back end of the drill bit in the drill pipe (called the finished curved shell). During drilling, the drill string does not rotate. When you need to change direction, the curved shell is positioned correctly and the right side is drilled along a smooth curve. The direction of the electronic viewfinder of drilling curve is to send the measurement results of drill pipe and drill bit placed at the back end to the receiver on the ground. After such data and operator's processing, it is displayed in digital form on the display. The electronic mobile equipment is mainly used to monitor the inclination of the sum of the magnetic fields between the drill pipe and the earth (the drill bit with three-dimensional coordinates is on the ground), and control the deviation between the actual position determined by comparing the measured data with the design data and the drill bit within the allowable range, and so on until the reservation.
2. Pre-reaming: The right rear guide is drilled and enlarged to facilitate the installation of finished pipes. This process is called pre-reaming diameter (reaming is determined according to the final hole size). For example, in a 36-inch pipe, the borehole must be enlarged to 48 inches or more. On the other side of the drilling rig, under normal circumstances, after the reamer is connected to the drill string, the pilot hole is rotated back and dragged, and the pilot hole is enlarged, so that a large amount of mud is pumped into the well hole, which is convenient for the drilling rig to drill, avoid landslides and mudslides, ensure data integrity and cut back to the ground.
3. Call back the pipe, pre-reaming the finished pipe, which can be dragged into the well after completion. The other side of the pipeline is prefabricated to complete the drilling rig. The drill pipe reamer has one end connected to the finished pipe and the other end connected through a rotary joint. Secondly, the rotary joint of the reamer rotates to avoid drilling holes in the finished pipe to ensure its smooth dragging. There is still a process for drilling rig callback, and the mud and callback processes should be specified continuously, because the pipeline on the platform side is not complete until the reamer appears for the first time.
Layout and design of the website
road
Both sides of the construction site need heavy equipment to reduce costs. Both parties shall provide the owner with the roads on the construction site, try to reduce the number of new roads by using the distance of existing roads, or use the road use agreement of pipeline construction access roads. We will discuss these issues in the bidding stage, which is too late.
B, one party's workplace
Rig-The rig construction site needs an area at least 30m (100ft) wide and 45m (150ft) long. The burial area should be located in the designated area of meters (10 feet), and many drilling rig equipment or accessories have no designated storage location, so many irregular small pieces on the construction site at one side of the drilling rig can save at least several floors of space, and be as flat, hard and clean as possible to facilitate the construction site. A large amount of fresh water mixed mud is needed in the construction site, so it is possible or easy to cross with water as the connection of tap water pipeline.
2. One side of the pipeline-a simple prefabricated pipeline, one side of the pipeline has a long enough construction site, which is the key consideration. Pipeline construction? The width of the site (generally 12- 18m) shall meet the requirements. The excavation site in Tongfang, Tsinghua requires the construction site to be 30m (100ft) and 40m (150ft) wide. The theme of the time is to prefabricate the pipeline (the total length of the website is generally 30 meters before the total length of the pipeline), including welding. Through the ball pressure test, the anti-corrosion process lags behind the pipeline connection work, because the callback process is a continuous pipeline connection, which may lead to the collapse of the underground cave and the failure of the whole building.
C, the construction site inspection
Once the appropriate response area is determined? Investigate the construction site and draw detailed and accurate geological feature maps. The accuracy of the final construction depends on the accuracy of the survey results.
D, construction drawing design parameters
Thickness of overburden-factors to be considered include river runoff characteristics, seasonal flood depth, future river expansion and deepening, and the location of existing pipelines and cables. Once the website is built and the geological survey is completed, it is generally determined that the overburden of the passing layer should be at least 6 meters (20 feet) thick. Not only additional requirements, obstacles such as crossing the river.
2. Most of them go through drilling and construction-the radius of curvature of buried angle is usually 8- 12 degrees, and most buildings need to drill a section between oblique straight lines and then a section with large radius curve. The curvature radius of the curve provides the bending characteristics of the finished pipe, and the rule of thumb is 100FT/IN when the diameter increases (generally 1000- 1200 times the pipe diameter). Diagonal wiring design is guided by the depth of the pilot hole curve, according to the predetermined direction, then a long and deep horizontal line, and then to the upward curved point-to-point excavation. The angle should be controlled between 5- 12 degrees to facilitate the resistance of the finished pipe behind.
E, drilling
The measuring guide tool includes downhole electronic equipment and measuring ground receiving equipment, which can measure the position, magnetic azimuth (left/right control), inclination (up/down control) and drilling direction of the drill bit.
1, accuracy: the accuracy of crossing construction depends largely on the change of magnetic field. For example, large steel structures (bridges, piles, other pipelines) and power lines can affect magnetic field readings. The target deviation of excavation through the pilot hole should be controlled within the range of about 3m (10ft) -3m and10ft (-10℃ 30ft).
2. Complete drawings: In general, each drill pipe should be drilled with a pilot hole for measurement and control, and measurement or calculation should be made every 9 meters (30 feet). The Contractor shall provide the Owner with the construction drawings of the above survey guide holes. Alternative methods used, such as gyroscope, acupuncture radar and intelligent pig ball positioning.
geological survey
The number of exploration holes depends on the whole website category and cross-length plan. The span is 300 meters (1000 feet), which is enough for each borehole to cross the site. If the drilling results show that the geological conditions in this area are relatively simple, further drilling sampling is unnecessary. If the exploration report shows that there are areas with more complicated geological conditions, or there are rocks or coarse sand layers, then you need to do further detailed geological investigation. The whole construction is long-distance and large-caliber, with coarse sand, pebbles and weathering. If there are obvious signs that geological rocks or hard rocks are very complicated, more geological drilling and sampling work are needed for the structure of 240m (600-800ft) 1 800,000-. All sampling probe holes should be along the whole cross-sectional direction, and the overall depth thematic map of sampling depth should be made. If possible, it is best to choose the outside of the center line of the sampling probe hole about 8 meters (25 feet). After the exploration task is completed, the exploration hole must be closed to prevent slurry leakage during construction.
B, exploration hole depth
All holes should penetrate at least 0/2m (40ft) of the transfer station/kloc-or plan to pass the following 6m, with the deepest depth (20ft), whichever is higher. Sometimes, it is very useful for both the contractor and the owner to go deep into the actual situation, or to go deep into the whole curve, than to get the design in place. Choosing the location of key intersections to form a social stratum structure is conducive to the formation of holes and is not conducive to the success of intersections.
C, soil classification
Geologists or qualified geologists should classify according to the unified soil classification system or the design documents of ASTM D-2487 and D2488. It will be useful to build a website to provide drilling records of field technicians or drilling companies in the future. The record will include the classification of visible materials and the interpretation and evaluation of the sampling results by the drilling company according to the formation structure.
D, standard puncture test
SPT In order to better determine the density of granular materials, geological engineers usually carry out penetration test SPT according to ASTM standard D 1586. This is a field test method. Drive the standard heavy hammer into the soil to a certain depth, and the depth recorded by the spoon sampler is 12 inch. The obtained data are used to estimate the standard value of non-polymer soil and the relative density of puncture resistance in the test site. Some drilling companies will choose to carry out small-scale tests in combination with soil or rock areas to determine the consistency of compacted soil and rock hardness.
e，
Core sampling method
Geological exploration companies prefer to use core sampling to obtain underground core samples, and these tests usually conform to ASTM specification D-1587. This test is similar to the standard penetration test of each steel pipe, except that the thin-wall sampling is hydraulically driven with a sharp cutting edge. Is it the expected oil pressure value? Records can be found on site, which is the first choice for complete sample analysis and more detailed test room. In order to meet the needs of construction, the hand-held puncture instrument is used to directionally cross the cutting spoon sampler.
f，
Sample size analysis of the scale screen analysis, the mechanical test samples of granular materials used in the construction site by cutting the spoon shape, the samples are sent to the laboratory, and through a series of screens, the size and weight of particles, which is the most important test of different diameters.
In the case of rocks
It is necessary to determine the formation type, relative hardness and ultimate compressive strength. The professional exploration company used found the existing rocks in the soil investigation, and sampled the diamond core barrel with a diameter of 50 mm (2 inches). The total length of rock types, the core compressed by geological experts and the classification of nuclear experimental rock masses are all based on the understanding of the relationship between rock hardness, the understanding of material hardness and the accurate measurement of core compressive strength. These data can also be estimated in order to determine what type of traversing equipment and drill bit pass through the lens.
The whole company can find it online. I'm working on a big project, and there are many intersections. I don't know what you do. If you are interested, we discussed this research.