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FAQ-1: What is Horizontal Directional Drilling?
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As its name implies, Horizontal Directional Drilling means the drilling of boreholes underground in a horizontal attitude, roughly parallel to the earth’s surface. Originally developed for the efficient production of oil and gas at great depths, the technology has evolved to also allow horizontal drilling very near the earth’s surface. The original drivers for this technology were pipeline companies who often had to lay pipelines under rivers, canals, highways, commercial structures and the like. They needed a more cost effective method than the blind drilling that was commonplace. Thus the Horizontal directional drilling (HDD) market was developed in which a steering tool behind the drill bit was used to sense the local magnetic field, compute its geographical location and steer the bit in a known and measured direction.While there have been many variations in field geometry, tool design and field techniques, the basic concept is unchanged. |
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FAQ-2: Why should I use Prime Horizontal?
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Since its inception, Prime Horizontal has been the prime driver, co-developer (with Vector Magnetics) and the prime user of the ParaTrack system of horizontal magnetic guidance. As a result, Prime Horizontal is considered the foremost authority on the deployment of the ParaTrack system in all horizontal directional drilling applications.In point of fact, Prime Horizontal strongly believes it is the only HDD service company capable of successfully completing some of the projects described in the pages of this website.The successful completion of some HDD projects requires the actual pre-operations design of new magnetic sources to adequately reduce magnetic interference from nearby electrical or magnetic sources. For example, the 3-D magnetic field of a long wire is different than that produced by a circular coil of wire or by a “square” coil or by a long elliptical coil. The correct choice therefore is important to overall success.
Many early magnetic sources used in the HDD industry generated DC (constant) magnetic fields. In a magnetically “quiet” environment, these sources work very well, but in a magnetically “noisy” environment, especially in the vicinity of time-varying magnetic interference, the use of magnetic sources that generate AC (cyclically varying) magnetic fields are required. Vector Magnetics and Prime Horizontal have developed such sources, and with their proprietary signal processing software, unparalled precision in magnetic guidance is now possible for a wide variety of applications.
It is of prime importance that the HDD contractor choose the optimum magnetic source for each project. Prime Horizontal makes the selection of the magnetic source part of its service package, often including the design of sources for specific use on specific projects. |
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FAQ-3: How does magnetic steering work?
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The magnetic field produced by the differential rotation of layers of the earth’s molten core is of course responsible for the workings of a compass, a magnetized needle that points to the North magnetic pole. Perhaps not so commonly understood is that our earth’s magnetic field is really a 3-dimensional vector field with one magnetic component pointing to the center of the earth, the 2nd magnetic component parallel to the earth’s surface pointing to the North and the 3rd magnetic component parallel to the earth’s surface pointing to the West. Our typical compass only senses the horizontal component of the earth’s magnetic field that points to the North. If we had a compass that could measure the direction of each component of the earth’s field and also the strength of the field along each of these 3 directions, then we could measure exactly our position in space at the location of our 3-dimensional compass because we have tables that list the earth’s magnetic field components at every point.This rather long, but conceptually simple explanation, is all we need to know to define magnetic steering. The 3-dimensional compass is called a 3-component magnetometer. Instead of magnetized needles, the sensing components are electronic, but they measure the same thing – the 3 strengths and 3 directions of the earth’s magnetic field at the precise location of the magnetometer. The magnetometer will thus always orient itself along the 3 magnetic components of the earth’s field. Placed inside a non-magnetic case and deployed inside a non-magnetic drill collar just behind the drill bit, we now have a device, called a magnetic guidance (or steering) tool, that measures these 3 magnetic components and produces an attitude and direction. Transmitting this information back up the drill pipe on a wire to a receiving unit tells the driller what he or she must do to maintain the borehole on a pre-designed course.Magnetic steering is therefore steering the drilling of a borehole according to the magnetic data received from the steering tool. |
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FAQ-4: If I can steer a borehole with the earth’s magnetic field as a source, why should I consider alternative magnetic sources?
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While the earth’s magnetic field is always present, the magnetic field actually measured at the point location of the steering tool is the vector sum of the earth’s field PLUS ALL OTHER LOCAL MAGNETIC FIELDS produced by ferrous materials in the vicinity of the tool or by nearby power or utility lines. These ferrous materials could be a part of the local composition of the earth or could be caused by nearby pipelines or other buried structures. Local magnetic fields near the earth’s surface are also caused by nearby power lines, utility lines, railways or highways.These local magnetic fields are often very strong and are time varying as, for example, that caused by a passing train or truck, or by magnetic storms emanating from our sun. It is the unfortunate fact that the strength and direction of these local field variations are often greater than the quiescent earth’s magnetic field components. Therefore the steering tool will guide itself along the “wrong” course defined by the local magnetic anomalies and time varying magnetic anomalies rather than along the predetermined course.In order to reduce the effects of local magnetic variations, strong magnetic sources with predetermined geometries and predictable magnetic fields are deployed at known locations to provide strong magnetic signals for the steering tool to use to measure its location. The magnetic fields produced by these sources are stronger than the earth’s field and stronger than the local or time-varying magnetic variations, so the steering tool is no longer unduly influenced by either the earth’s field or by the local magnetic variations. |
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FAQ-5: What is ParaTrack?
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ParaTrack is an underground magnetic tracking system with unique capabilities. Rather than using a conventional surface coil, ParaTrack’s surface deployment will often be a guidewire along centerline with a return cable placed offline so its magnetic signal is negligible. In specific circumstances, the centerline cable may be grounded on each side of the crossing, negating the need for a return path with its significant deployment time.Today, ParaTrack is the only tracking system able to utilize many different magnetic sources. Not only do we use guide wires on the surface or underground, we also use the Rotating Magnet Sub, the AC Beacon and the MGT Sub, all requiring no guidewires. One of these choices will fit the exacting requirements of most horizontal drilling projects.Additional sources are in current development for new applications that require even more exacting specifications. |
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FAQ-6: How soon will you respond to my request for a quotation?
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Prime Horizontal considers that communication with our customers and potential customers is of paramount importance to our business success.We will make our best effort to respond to your request for quotation and information within 24 hours of our receipt of your request. |
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FAQ-7: Can you send me a standard pricelist for your services?
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We can provide standard day rates for our services and equipment rentals, but we have found through years of experience that the one constant factor in all projects is that they are all quite different. As a result, turn-key pricing is quite difficult to estimate until we thoroughly understand your project through detailed discussions and, possibly, site visits. |
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FAQ-8: Can you send me a standard pricelist for equipment rentals?
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We can send prices for most inventory items only within a specific geographic location due to the continuously changing cost of steel and the volatile exchange rates of the past 4 years, |
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FAQ-9: What is Coal Bed Methane?
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Coal Bed Methane (CBM) is naturally occurring methane gas (CH4) in coal seams. It is referred to also as Coal Seam Methane (CSM) and Coal Seam Gas (CSG). Methane which is associated with coal mining operations is called Coal Mine Methane (CMM). Methane was long considered a major problem in underground coal mining but now CBM is recognized as a valuable resource.CBM is held in place by water pressure and does not require a sealed trap as do conventional gas accumulations. The coal acts as a source and reservoir for the methane gas while the water is the seal. It is called ‘sweet gas’ because of its lack of hydrogen sulfide.When the water is pumped or removed from the coal seam, the gas is desorbed from the coal and released. This can be captured through a gas well that is drilled either vertically or horizontally through the coal seam. |
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FAQ-10: Drilling for Coal Bed Methane (CBM)
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CBM can be extracted using a vertical well which passes through the coal seam or a horizontal well which is drilled along the coal seam. Frequently the gas is extracted by using a combination of vertical and horizontal wells. When this is the case, the vertical well would be intersected by a horizontal well in the coal seam. Vertical wells are drilled from surface through the seam. These are cased to required levels, normally just above the seam and then cemented in place. The Horizontal Well can either start from vertical rigs or from HDD rigs mounted on an angle. They are drilled in several stages. The first stage is drilling a short distance from surface into the bedrock and running large diameter casing. The next stage is to drill the ‘build’ section. The build section starts from the entry angle and “builds” to the seam angle, thereafter entering the coal seam. There can be a section before and after the angle build where angle is held constant to allow a predefined build curve to be constructed and seam entry to take place at an efficient location in respect to entry position. This is common when drilling with vertical entry as the seam can be quite deep and using a shorter radius allows seam entry closer to the entry point.
Upon entry into the coal seam, the inseam lateral is drilled. The objective of drilling the inseam lateral is to drill in the target coal seam and not drift into either the roof or floor interface. Precise location of the drill bit with the RMRS system is critical for drilling the inseam lateral. |
