History of horizontal directional drilling

The directionally controlled horizontal drilling process was developed in the U.S., and has become commonly used for installing pipelines under natural or manmade obstacles, especially river crossings. This method has revolutionized complicated river crossings for pipelines which were initially done by conventional dredging methods or were rerouted through long distances and crossed over at a bridge location.

If you are looking for more details, kindly visit our website.

The method, an outgrowth of the oil well drilling technology, was reportedly first developed in the early s by Titan Construction, of Sacramento, California. The first installation was accomplished in for Pacific Gas & Electric Co., and involved the installation of approximately 600 lf (180 m) of four-inch diameter steel pipe under the Pajaro River near Watsonville, California. Prior to , the method was limited to the installation of short lengths. In , the method was acquired by Reading & Bates Construction Company (Now Inarc Drilling, Inc.), Tulsa, Oklahoma. Since , the method has progressed to state-of-the art where long lengths of crossing with a wide variety of pipe sizes can be accomplished.

From to , only 36 crossings were made using this method, all of them in the United States. However, in the next seven years, over 175 crossings were made, with several accomplished in South America, Europe, Africa and Asia. Currently, there are several firms competing in the market, and the total number of crossings exceed well over 500.

For a time, horizontal directional drilling (HDD) was primarily used by the oil and gas industry on large-diameter, cross-country pipeline transmission lines. Increasingly, it is being approved and used for small-diameter gas distribution lines in urban and suburban areas, as well for municipal water and telecommunication cable crossings at airports, highways, and waterways.

HDD has become the preferred technique of many pipeline and utility companies by virtue of its lower costs and decreased surface disruption. Because it minimizes the negative impact of construction on the surrounding areas, HDD provides a method of installation that is unsurpassed in its ease and overall &#;friendly&#; nature. Pipeline companies have been increasingly turned to HDD over traditional, open-trench methods for underground construction projects.

Equipment and systems

Introduced in the s, the first HDD rigs were considered difficult to operate. But improvements came quickly, and more manufacturers developed products as utility companies and contractors recognized the advantages offered by the technique.

A basic HDD system is highly user friendly, and includes a drill frame, power source, hydraulics, drilling fluid and guidance systems. No starting pits are needed; bores are launched from the surface and proceed downward at an angle until the necessary depth is reached. Then the path of the bore is leveled, and the bore head is steered to a designated exit point, where it is brought to the surface.

As the bore progresses, lengths of drill pipe are added. When the initial bore is complete, material to be installed is attached to the drill string, often with a backreamer, to enlarge the diameter of the borehole. The installation is made by pulling the product pipeline back through the borehole, with drill pipe sections being removed as the drillstring approaches the drill frame.

Drilling fluid is used in making the initial bore, and during pullback. For utility work, bore lengths generally range from 50 to 600 ft, but, with some systems, can extend as far as 1,800 ft.

HDD equipment has evolved dramatically over the past 10 years. The introduction of a reliable walk-over locating system spawned the initial growth of the mini- and midi-class drills that use high drilling fluid pressure (up to 5,000 psi) and low drilling fluid volume (2-10 gpm). This method of drilling is effective in soft to medium ground conditions.

Initially, manufacturers custom-built each drill, making improvements and design changes based on suggestions and feedback from their customers. The next hurdle to overcome for the mini- to midi-class drills was to be able to successfully bore in hard soil and solid rock conditions.

A boom in oilfield horizontal drilling forced the development of small-diameter downhole mud motors. The maxi-class HDD rig operators had been using large-diameter mud motors successfully for years. Industry demands led the manufacturers to develop the necessary design changes, to enable the use of small-diameter, lower-flow mud motors (minimum 30-40 gpm required). Having expanded the capacities of the mini- and midi-HDD rigs with higher flow mud pumps, the need to limit job setup space or rig footprint led to the concept of self-contained HDD Rigs.

The development of small HDD Rigs with the power sources, drilling mud fluid pump and hydraulic pumps all mounted on a mobile drill carriage then began, and manufacturers of self-contained HDD move rapidly forward. Currently, a contractor can obtain mini-HDD rigs fully self-contained, including an on-board drilling water supply to midi-HDD rigs supported only by an additional water/drilling mud source.

Along with the development of these higher flow output mini- and midi-class rigs, the need for a mud cleaning, mixing and recirculating system began to evolve. Minimizing drilling mud spillage at the bore entry site while lowering mud cost made the cleaning and mixing system a logical investment for many contractors.

At the same time HDD rigs were evolving, so were various downhole supporting tools. Drill pipe, once thought by many to be a low-cost, expendable item, is now usually the second-highest dollar amount on a purchase order for a new HDD rig. Early examples of pipe threads varied widely ­&#; left-hand, right-hand, even &#;rope&#; threads have been replaced with API-approved thread designs. Forged drill pipe has become standard on most midi-class rigs.

The evolution of walk-over locating systems has been almost as dramatic as that of the HDD rigs themselves. Early systems were limited to very shallow depths, and information update times were extremely slow by today&#;s standards. Now, not only do contractors have a choice of sondes to match their project scopes, but wireline steering tools have been simplified. Walk-over system status readouts that are broadcast back to the driller&#;s console enable the driller and locator to see the information simultaneously.

The variety of drill bits or heads and back reamers can be overwhelming to a contractor. Each style of bit or reamer has a designated purpose. Most contractors will find a bit/reamer design that consistently works in their typical soil conditions, and will employ that style almost exclusively.

Currently, the trend in the industry is contractor diversification. They want to have the capacity to not only be able to bore in the service lines from the right-of-way to the house, but also be able to handle longer, harder formation bores. Realistically, this type of project work requires more than one class of machine. The development of the mini-, self-contained drills has satisfied a majority of service-type work.

The midi-class of rigs has undergone big changes in recent years. Various manufacturers have developed midi-rigs that are relatively compact in size, yet powerful enough to tackle the occasional difficult bore.

Some of the more experienced HDD contractors have gained enough confidence to move into the maxi-class of rigs. This move, according to some contractors, can be as overwhelming as buying their first HDD rig. Larger projects require more planning, more time and more support. However &#; assuming that no unexpected disaster occurs &#; the financial reward is usually greater.

A growth industry

The use of HDD grew throughout the s, but was still not as commonplace as it has become today. By the end of the decade, directional drilling was a technique to be tried when other construction methods could not be used.

But the technique saw tremendous growth in the s, as the need for environmentally friendly installation methods grew. In , about 30% of all underground work was completed with directional drilling equipment. That figure increased to close to 50% in and , as demand from the telecommunications companies joined that of pipelines and utilities.

That rapid growth has slowed with the recent downturn in the telecommunications and internet-broadband industries. But demand for trenchless installation techniques from pipeline companies and utilities has remained strong, and is expected to increase in the future. This is due to advantages HDD offers in the environmental, technical, contractual and economic arenas.

Today, utilities and contractors often make HDD their first choice. In the early days, the only obvious drawback to choosing HDD was that the technology was so new, there was not a large pool of experienced personnel to draw from. This has changed as well. In , there is a much larger amount of experience regarding HDD, on the part of operators, contractors, public officials and regulators.

In no small part, this is because contractors, equipment manufacturers, and service companies teamed together to develop educational HDD programs. These programs aid in the development of competent HDD employees. The initial learning curve of a new horizontal directional drill owner is dramatic in its rapid up-slope. However, after the initial knowledge is attained, moving to the next level can be difficult without support from the manufacturers, dealers and service companies. Recognizing this need, schools and one-on-one training courses are available from an increasing number of sources.

Utility construction, particularly in the gas and telecommunications industries, ensures a growing demand for the use of directional drilling techniques into the 21st century. The potential for work spans the spectrum, from major river crossings to utility installation in congested urban areas, to various types of environmental remediation.

Compact HDD systems can be used to install service lines to residences, without damaging private or public property, and other utility systems. These (usually smaller) rigs are able to bore beneath driveways and sidewalks, existing utility lines, and underground sprinkler systems. Larger directional drilling equipment can be used to go under parking lots, highways, freeways, and even rivers and lakes.

In addition, HDD offers unique solutions to environmental problems. For example, directional systems can install horizontal remediation wells to access contaminated soil and ground water in areas where other procedures are uneconomical. Some in the industry predict the environmental market for HDD will eventually be larger that the utility market.

Overall, HDD reduces restoration time and costs in both urban areas and residential neighborhoods. The public appreciates the reduced inconvenience made possible by the use of directional drilling equipment.

Applications

Companies usually consider the technical, contractual, and economic aspects of a project when determining whether to use HDD. In the case of a river crossing, the project is determined to be technically feasible if it can be installed using existing tools and techniques, regardless of uncertainties surrounding installation cost. A crossing is contractually feasible if the installation cost can be accurately estimated in advance, allowing contractors to submit lump-sum bids. HDD is economically feasible if installation cost is less than the cost of competing construction methods.

Mini-HDD is a subsurface-launched installation technique that typically uses either controlled-fluid cutting or fluid-assisted mechanical cutting. However, this method can be use air for cooling or dry boring assistance, or can be a dry process where neither liquid (e.g., bentonite, water) nor air is used. Therefore, the choice of fluid-assisted or dry cutting depends on the nature of work (normal utility application or environmental application), size of the utility line (diameter and length), subsurface conditions, and impact on the environment.

The feasibility for using the mini-HDD technique should be initially established on the basis of diameter length, and required/achievable degree accuracy in alignment and grade. Mini-HDD currently is not practical for installing pipe to the precise alignment and grade tolerances required for gravity sewer line. However, mini-HDD is suited for installing new utility networks for water, gas, electric or telecommunication lines in developed areas. It can also be used to install pressure sewer line. The diameter of the product pipe or utility line to be installed using this technique should be somewhere in the 2 to 10-in. range. The depth should be less than 30 ft.

The dry system is suitable only for small-diameter pipelines (typically less than 4 in.) and short (typically less than 150 ft) utility line installations. It is useful for drilling through soft soil or drilling under a sensitive, contaminated site where the probability of contamination movement to ground water or to the surface is high. It may also be applicable where hazardous or toxic wastes have a high probability of contaminating drilling fluids, which would then require proper disposal.

The main drawbacks of dry boring are the limitation of pipe size and overheating of the drill head as the bore diameter and the length of the bore increases. Also, it should be remembered that the dry boring system (with or without air) is usually less responsive to steering corrections than fluid-assisted mechanical cutting.

Fluid-assisted mechanical boring is appropriate for most utility applications, and the low drilling fluid volume used is unlikely to cause voids or settlement problems. Moreover, the fluid assisted mechanical cutting system is very useful for coarse, saturated, sandy soils where drilling fluid stabilizes the borehole.

An important distinction between fluid-assisted mechanical boring and water-jet boring is that the high fluid volumes and pressures used in water-jet boring often cause erosion of the soil adjacent to the borehole. Water-jet boring uses large volumes of water at pressures as high as 15,000 psi for cutting the soil, while mini-HDD uses water pressure less than 4,500 psi to assist in mechanical cutting by the drill head.

Another factor that should be considered for selecting the method of installation is the steerability of different techniques. Steerability is important for curved space alignment, or where the clearance between the existing utility lines is small. It is important to determine the minimum radius of curvature attainable with specified diameter drill pipe for each method. The minimum radius of curvature is typically given as 125 ft for 1.5-in. diameter pipe, although some manufacturers state that radii of 42.5 ft for 1.25-in. pipe and 30 ft for 1.0-in. pipe are not unusual. Drill rod life can be adversely affected by use of sharp bends.

The mini-HDD method is best suited for soils with some cohesion (i.e., clays). The method is also successfully used in sandy soils by adding bentonite to the drilling fluid, to ensure borehole stability. Hard soils, caliche, shale, limestone and other rocks typically reduce the drilling rate and increase, and increase drilling head wear. The mini-HDD method is not well suited for gravelly soils (greater than 25% gravel sizes).

Practice of drilling non-vertical bores

A horizontal directional drill in operation A structure map generated by contour map software for an 8,500-foot-deep (2,600 m) gas and oil reservoir in the Erath field, Vermilion Parish, Erath, Louisiana. The left-to-right gap, near the top of the contour map indicates a fault line. This fault line is between the blue/green contour lines and the purple/red/yellow contour lines. The thin red circular contour line in the middle of the map indicates the top of the oil reservoir. Because gas floats above oil, the thin red contour line marks the gas/oil contact zone. Directional drilling would be used to target the gas and oil reservoir.

Directional drilling (or slant drilling) is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring (horizontal directional drilling - HDD), and surface in seam (SIS), which horizontally intersects a vertical bore target to extract coal bed methane.

History

[

edit

]

Many prerequisites enabled this suite of technologies to become productive. Probably, the first requirement was the realization that oil wells, or water wells, do not necessarily need to be vertical. This realization was quite slow, and did not really grasp the attention of the oil industry until the late s when there were several lawsuits alleging that wells drilled from a rig on one property had crossed the boundary and were penetrating a reservoir on an adjacent property.[citation needed] Initially, proxy evidence such as production changes in other wells was accepted, but such cases fueled the development of small diameter tools capable of surveying wells during drilling. Horizontal directional drill rigs are developing towards large-scale, micro-miniaturization, mechanical automation, hard stratum working, exceeding length and depth oriented monitored drilling.[1]

Measuring the inclination of a wellbore (its deviation from the vertical) is comparatively simple, requiring only a pendulum. Measuring the azimuth (direction with respect to the geographic grid in which the wellbore was running from the vertical), however, was more difficult. In certain circumstances, magnetic fields could be used, but would be influenced by metalwork used inside wellbores, as well as the metalwork used in drilling equipment. The next advance was in the modification of small gyroscopic compasses by the Sperry Corporation, which was making similar compasses for aeronautical navigation. Sperry did this under contract to Sun Oil (which was involved in a lawsuit as described above), and a spin-off company "Sperry Sun" was formed, which brand continues to this day,[when?][clarification needed] absorbed into Halliburton. Three components are measured at any given point in a wellbore in order to determine its position: the depth of the point along the course of the borehole (measured depth), the inclination at the point, and the magnetic azimuth at the point. These three components combined are referred to as a "survey". A series of consecutive surveys are needed to track the progress and location of a wellbore.

Prior experience with rotary drilling had established several principles for the configuration of drilling equipment down hole ("bottom hole assembly" or "BHA") that would be prone to "drilling crooked hole" (i.e., initial accidental deviations from the vertical would be increased). Counter-experience had also given early directional drillers ("DD's") principles of BHA design and drilling practice that would help bring a crooked hole nearer the vertical.[citation needed]

Additional reading:
How to Choose hammer mill crusher?

coredrillpros. supply professional and honest service.

In , H. John Eastman and Roman W. Hines of Long Beach, California, became pioneers in directional drilling when they and George Failing of Enid, Oklahoma, saved the Conroe, Texas, oil field. Failing had recently patented a portable drilling truck. He had started his company in when he mated a drilling rig to a truck and a power take-off assembly. The innovation allowed rapid drilling of a series of slanted wells. This capacity to quickly drill multiple relief wells and relieve the enormous gas pressure was critical to extinguishing the Conroe fire.[2] In a May, , Popular Science Monthly article, it was stated that "Only a handful of men in the world have the strange power to make a bit, rotating a mile below ground at the end of a steel drill pipe, snake its way in a curve or around a dog-leg angle, to reach a desired objective." Eastman Whipstock, Inc., would become the world's largest directional company in .[citation needed]

Combined, these survey tools and BHA designs made directional drilling possible, but it was perceived as arcane. The next major advance was in the s, when downhole drilling motors (aka mud motors, driven by the hydraulic power of drilling mud circulated down the drill string) became common. These allowed the drill bit to continue rotating at the cutting face at the bottom of the hole, while most of the drill pipe was held stationary. A piece of bent pipe (a "bent sub") between the stationary drill pipe and the top of the motor allowed the direction of the wellbore to be changed without needing to pull all the drill pipe out and place another whipstock. Coupled with the development of measurement while drilling tools (using mud pulse telemetry, networked or wired pipe or electromagnetism (EM) telemetry, which allows tools down hole to send directional data back to the surface without disturbing drilling operations), directional drilling became easier.

Certain profiles cannot be easily drilled while the drill pipe is rotating. Drilling directionally with a downhole motor requires occasionally stopping rotation of the drill pipe and "sliding" the pipe through the channel as the motor cuts a curved path. "Sliding" can be difficult in some formations, and it is almost always slower and therefore more expensive than drilling while the pipe is rotating, so the ability to steer the bit while the drill pipe is rotating is desirable. Several companies have developed tools which allow directional control while rotating. These tools are referred to as rotary steerable systems (RSS). RSS technology has made access and directional control possible in previously inaccessible or uncontrollable formations.

Benefits

[

edit

]

Wells are drilled directionally for several purposes:

• Increasing the exposed section length through the reservoir by drilling through the reservoir at an angle.
• Drilling into the reservoir where vertical access is difficult or not possible. For instance an oilfield under a town, under a lake, or underneath a difficult-to-drill formation.

• Allowing more wellheads to be grouped together on one surface location can allow fewer rig moves, less surface area disturbance, and make it easier and cheaper to complete and produce the wells. For instance, on an oil platform or jacket offshore, 40 or more wells can be grouped together. The wells will fan out from the platform into the reservoir(s) below. This concept is being applied to land wells, allowing multiple subsurface locations to be reached from one pad, reducing costs.
• Drilling along the underside of a reservoir-constraining fault allows multiple productive sands to be completed at the highest stratigraphic points.
• Drilling a "relief well" to relieve the pressure of a well producing without restraint (a "blowout"). In this scenario, another well could be drilled starting at a safe distance away from the blowout, but intersecting the troubled wellbore. Then, heavy fluid (kill fluid) is pumped into the relief wellbore to suppress the high pressure in the original wellbore causing the blowout.

Most directional drillers are given a blue well path to follow that is predetermined by engineers and geologists before the drilling commences. When the directional driller starts the drilling process, periodic surveys are taken with a downhole instrument to provide survey data (inclination and azimuth) of the well bore.[3] These pictures are typically taken at intervals between 10 and 150 meters (30&#;500 feet), with 30 meters (90 feet) common during active changes of angle or direction, and distances of 60&#;100 meters (200&#;300 feet) being typical while "drilling ahead" (not making active changes to angle and direction). During critical angle and direction changes, especially while using a downhole motor, a measurement while drilling (MWD) tool will be added to the drill string to provide continuously updated measurements that may be used for (near) real-time adjustments.

This data indicates if the well is following the planned path and whether the orientation of the drilling assembly is causing the well to deviate as planned. Corrections are regularly made by techniques as simple as adjusting rotation speed or the drill string weight (weight on bottom) and stiffness, as well as more complicated and time-consuming methods, such as introducing a downhole motor. Such pictures, or surveys, are plotted and maintained as an engineering and legal record describing the path of the well bore. The survey pictures taken while drilling are typically confirmed by a later survey in full of the borehole, typically using a "multi-shot camera" device.

The multi-shot camera advances the film at time intervals so that by dropping the camera instrument in a sealed tubular housing inside the drilling string (down to just above the drilling bit) and then withdrawing the drill string at time intervals, the well may be fully surveyed at regular depth intervals (approximately every 30 meters (90 feet) being common, the typical length of 2 or 3 joints of drill pipe, known as a stand, since most drilling rigs "stand back" the pipe withdrawn from the hole at such increments, known as "stands").

Drilling to targets far laterally from the surface location requires careful planning and design. The current record holders manage wells over 10 km (6.2 mi) away from the surface location at a true vertical depth (TVD) of only 1,600&#;2,600 m (5,200&#;8,500 ft).[4]

This form of drilling can also reduce the environmental cost and scarring of the landscape. Previously, long lengths of landscape had to be removed from the surface. This is no longer required with directional drilling.

Disadvantages

[

edit

]

Government Accountability Office depiction of horizontal drilling being used to cross tracts of land with differing owners

Until the arrival of modern downhole motors and better tools to measure inclination and azimuth of the hole, directional drilling and horizontal drilling was much slower than vertical drilling due to the need to stop regularly and take time-consuming surveys, and due to slower progress in drilling itself (lower rate of penetration). These disadvantages have shrunk over time as downhole motors became more efficient and semi-continuous surveying became possible.

What remains is a difference in operating costs: for wells with an inclination of less than 40 degrees, tools to carry out adjustments or repair work can be lowered by gravity on cable into the hole. For higher inclinations, more expensive equipment has to be mobilized to push tools down the hole.

Another disadvantage of wells with a high inclination was that prevention of sand influx into the well was less reliable and needed higher effort. Again, this disadvantage has diminished such that, provided sand control is adequately planned, it is possible to carry it out reliably.

Stealing oil

[

edit

]

In , Iraq accused Kuwait of stealing Iraq's oil through slant drilling.[5] The United Nations redrew the border after the Gulf war, which ended the seven-month Iraqi occupation of Kuwait. As part of the reconstruction, 11 new oil wells were placed among the existing 600. Some farms and an old naval base that used to be in the Iraqi side became part of Kuwait.[6]

In the mid-twentieth century, a slant-drilling scandal occurred in the huge East Texas Oil Field.[7]

New technologies

[

edit

]

Between and , the Naval Civil Engineering Laboratory (NCEL) (now the Naval Facilities Engineering Service Center (NFESC)) of Port Hueneme, California developed controllable horizontal drilling technologies.[8] These technologies are capable of reaching 10,000&#;15,000 ft (&#; m) and may reach 25,000 ft ( m) when used under favorable conditions.[9]

Techniques

[

edit

]

Wellbore Surveys

[

edit

]

Specialized tools determine the wellbore's deviation from vertical (inclination) and its directional orientation (azimuth). This data is vital for trajectory adjustments. These surveys are taken at regular intervals (e.g., every 30-100 meters) to track the wellbore's progress in real time. In critical sections, measurement while drilling (MWD) tools provide continuous downhole measurements for immediate directional corrections as needed. MWD uses gyroscopes, magnetometers, and accelerometers to determine borehole inclination and azimuth while the drilling is being done.

Trajectory Control

[

edit

]

• Bottom Hole Assembly (BHA): The configuration of drilling equipment near the drill bit (BHA) profoundly influences drilling direction. BHAs can be tailored to promote straight drilling or induce deviations.
• Downhole Motors: Specialized mud motors rotate only the drill bit, allowing controlled changes in direction while the majority of the drill string remains stationary.
• Rotary Steerable Systems (RSS): Advanced RSS technology enables steering even while the entire drill string is rotating, ensuring greater efficiency and control.

See also

[

edit

]

References

[

edit

]

Want more information on Directional Drill Machines? Feel free to contact us.