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Flora Boring now extends its service in dealing with “Directional Drilling” works by modern types and technologies, capable to work in rock areas even though if it is in hard rocks and the sand areas and under water. The innovative process for laying pipes (Steel and HDPE) and cables with well qualified personals who can assist in finding solution for any type of boring works with the most suitable Drilling machines along with a number of major advantages like Trench less, Ecological, Economical, safe and fast ways to obtain the best results.

We feel proud to say that only we, “FLORA BORING” can able to handle such works in hard rock areas in United Arab Emirates.

Well-qualified teams who can assist in finding solutions and the most suitable Directional Drilling machine can use to obtain for the best results.

And the way of works, keeping good relations with our valuable customers, satisfaction of our customers requirements are the factors which help us to grow and grow our company in the fields.

Directional Drilling Working Method :

Directional Drilling Method Statement :

Purpose : Install utilities (Pipes & or cables) underground, without disturbing ground surface.

The Jet Trac unit is anchored to the ground surface using anchor stakes, which are operated hydraulically.

The Directional boring bit (angled bit) is drilled into the ground using fluid assistance. The actual ground drilling is mechanical cutting by the drill bit. The fluid is a mixture of bentonite (pure clay oil and water – all natural). The fluid is sprayed at a low pressure out of the drill head to lubricate the drill procedure and to cool the electronic tracking components in the drill head.

The head is tracked from the ground surface using and electronic receiver. When directional control is required, the head is pushed by the drill unit without rotating / drilling, until the drill head eagle desired is reached.

When the drill head reaches the destination size of the horizontal bore, the head may be steered to the ground surface, or a receiving pit may be made.

The drill head will then be removed from the drill pipe and a back reamer with a pipe puller will be attached to the drill pipe, along with the pipe to be installed underground.

Back reaming and pulling the pipe at the same time will allow the pipe to be installed underground without excavation, Again, during back reaming, the drill fluid will assist the back reamer with lubricating the back reaming, and creating a slurried area for the pipe to be installed without any void.

The back reaming and pull back will continue until the back reamer and pipe reach the launch side of the directional bore, where the bore will then be complete.

Method Statement – Directional Drilling :

Directional Drilling Machines

With a Directional Drilling Machine you start a controlled horizontal drilling from the starting pit until the receiving pit.

Back reamer

A larger cutter head with the teeth on the reverse side and designed to cut as the drill string is being pulled back through the pilot hole.

Survey Probe

The assembly of electronic equipment that provides information for determining the location of the cutter head.

Deep Crossings – The Process :

This category is generally assumed to be applicable to depths greater that 24 feet. The process of Directional Drilling under an obstacle can differ in many ways. However, the principal and general methods remain the same. As in horizontal and vertical drilling, a machine provides the means for rotating, advancing and retracting the frill string. Depending on the specific project, a certain drill string diameter is selected. Selection of drill string diameter or capacity is largely dependent on the length of the crossing and the anticipated thrust and pull back required for the finished product line. Generally, the most common sizes used range from a nominal 2 inch diameter. The length of the drill stems vary from 10 to 35 with API or similar threads.

At the leading end of the drill string, a cutting head is attached. The cutting heads are usually equipped with exit holes, which directs a drilling solution to the cutting face. While the cutting head is being rotated into the ground, the drilling fluid is pumped through the drill string and passes through the holes in the head to remove cuttings. The drilling fluid is also used as a lubricant to reduce friction between the rotating parts and the ground.

Deep Crossings – The Setup :

A drilled crossing can be set up in several different ways. One method would be to drill in a constant arc or semi circle. The other method would be to enter a hole at a downward angle. The drill string is then directed into a horizontal position and advanced for the distance required to clear the obstruction. The drill string would then be directed at an upward angle to the exit point. Once this criteria is determined, a set back is figured for an entering and exiting point to and from the intended line. A general rule of thumb is that a drill string can bend, at the rate of once the project is established and the entering and exit pints are know, the process can begin. The drill rig is set up and the drill rack is set to the determined angle. This is usually 5 to 20 degrees, depending on the characteristics of the crossing. The initial drill string and cutter head are set into the drilling chuck. (Note : While the setup and drilling is proceeding, a made out of an antimagnetic material to eliminate any interference to the Survey Probe. This first section is setup to mount the Cutter head, Bend Sub, and the Survey Probe for guidance. Before the drilling process begins, a magnetic bearing is selected for the desired direction of travel They Survey Probe is calibrated to this bearing and installed in the first section.)

Deep Crossings – Steering System :

The drilling head incorporates a magnetic survey system, which can relay information to the drill operator such as drill head rotation drill head angle and magnetic bearing. This information is related to the operator by means of probe installed directly behind the cutter head in the first section of the drill stem. The data is usually transmitted to the surface via a single conductor wire. Most of the units are provided with a surface processor for computing the information.

Steering of the drill string is accomplished by the installation of what is commonly know as a Bend Sub.

Directly behind the back reamer (away from the drill stem) a bearing swivel is installed. The bearing Swivel is to attach to a puller that has been installed on the product line. As the product line is pulled in to the hole, the drill string is rotated and the drilling solution is pumped in to maintain the integrity of the hole. In cases where the product line or bundle of lines are larger than the pile hole, an oversized back reamer will be required. When back reaming for product line installation, a slightly larger hole than the product line is required so that the drilling solution can remove the cutting.

The amount of over cut is largely dependent upon soil conditions and the type of crossing or obstacle. In cases where the ground conditions are soft and basically un supporting, a rotary compaction is installed directly behind the back reamer. A rotary compactor is a barrel type tool with radial or coned type ends which when pulled and rotated through the ground, compacts the soil in the hole to maintain its integrity. The bearing Swivel is installed behind the compactor.

Much of the tooling and survey equipment used for directional drilling today has been in use for oil field drilling over a period of many years. One item that has been in use and is readily adaptable to directional drilling is a downhole motor.

The motors are designed and built in various diameter and torque rating to accommodate most drilling applications. Downhole motors are used where high cutter bit speed is desired. Rock boring and variable ground conditions are excellent applications for the Downhole motor. In most applications the motors are used in combination with the Bend Sub for Steering purposes.

The Bent Sub is an offset section of drill stem that causes the cutter head to turn eccentrically about its centerline when it is rotating. While the hole is being drilled, the drill string is rotated along with the cutter head as a single section. When steering adjustment are required, direction of travel and the drill string is advanced forward without rotation. The eccentric location of the cutter head relative to centerline of the drill string creates a wedge type effect when pushed without rotation. This causes the drill string to deflect in the desired direction. When steering corrections are made, the operator pushes the cutter head to the proper location. The drill string is then rotated to resume cutting. This process is repeated as many time as necessary to assure proper location of the cutter head as it progressed along the desired path.

Deep Crossings – Drilling Method :

When the drilling begins the drilling solution pump is turned on an the cutter head is rotated into the ground. As the first section is being buried, the operator monitors the head location and compares the information to a plotted chart. If there is any deviation from the intended line, the operator makes the steering corrections. Once the first section is buried, the drill section is uncoupled from the drill chuck and another section of drill stem is added. For each section of drill stem installed, a connector wire is also installed to complete the circuit for the Survey Probe. The sequence continues until the pilot hole is completed. Once the pilot hole is completed the product line should be ready to be pulled back. For pulling back a Product Line or lines first the cutter head is removed and a Backreamer is installed in its place. A backreamer is a cutting head with its cutter facing the drill string.

When a crossing is directionally drilled, various factors should be taken into account such as :
-Hole Size
-Required Curvature
-Hole Length
-Minimum Ground Coverage
-Survey Technique
-Magnetic Bearing
-Drilling Fluids
-Entrance Angle
-Exit Angle
-Drill Pipe
-Drilling Machine
-Pre-plotting Chart
-General Working Area

Shallow Crossings – The Process :

The next category to be described is shallow drilling of approx. 24 feet or less. The use of this type system has widely been accepted for residential type applications for the installation of gas, water, electric and utility line. The only three main difference between shallow type or residential drilling rigs and their Big Brothers are that :

-The Guidance System is different
-Maximum drilled crossings are shorter
-Smaller attainable hole size

The smaller rigs are designed to be light and easily moved by one or two persons. They provide the same action as the bigger rigs namely the rotary, push and pulling actions, they are only restricted to a lesser capacity. The steering features for small boring rods are somewhat similar to the Bent Sub sued on the larger rigs. For small sized drilled holes instead of suing the Bent Sub a beveled or wedge shaped cutter head is installed at he lead end of the drill string.

While cutting, the head and drill string are rotated. When a direction change is required, the rotation is stopped. The head is then rotated to the proper angle and pushed forward without rotation. Ground force against the wedge forces the cutting head to change direction. Once the drill string is aligned with the intended path, the drilling procedure resumes. For convenience drill rods are supplied in 5 and 10 foot lengths. The main difference is small directional drilling in the method of locating the drill head.

Shallow Crossings – Setup :

The setup for a small rig is very similar to the setup described under “Deep Crossings – Setup”. Instead of installing a magnetic probe, a radio sending unit is used. This is the only difference between the two setups.

Shallow Crossings – Steering System :

This method incorporates a radio type detector system, which can relay the location of the probe to a surface monitor. This person then relays the location to the machine operator. Necessary corrections are made based on the information provided.

These sending unit are battery powered and transmit a signal to the ground surface. The signals are received by a hand held receiver that displays the direction and depth. Generally on shallow bores, readings are taken every several feet along the intended drill path. One unique feature of this type of drilling is that there are not limitations to straight lines. Bores can be moved up or down, right or left, as the operator or the project requires. In some cases it has been documented that a 90 degree radius turn or even a complete circle can be drilled underground. The radio type locators decrease in accuracy as the hole gets deeper.

Small Directional Drills also lend themselves to features like the bigger rigs. Some of those features would include back reaming, downhole motors, rotary compaction tools and etc. Due to small rig power limitations, hole size are limited to 1 ½ inches in diameter up to 12 – 14 inches in diameter. In conclusion, Directional Drilling has become a unique way of installing underground.

Accessories :

Plan Bore Path :

The bore path, from entry to end, must be planned before boring begins. Bore path can be marked on ground with spray paint of lags, or written on paper for operator reference.

For complicated bores, consult an engineer. Have jobsite surveyed and bore path calculated. Be sure engineer knows minimum entry pitch, bend limits of drill pipe and pullback material, pipe lengths and location of all underground utilities.

For less complicated paths, bore will be limited by four measurements : recommended bend limits, entry pitch, minimum set-back, and minimum depth. Recommended bend limits must be considered during any bend, not just during bore entry.

Recommended Bend Limit :

Though Ditch Witch pipes are designed to bend, bending beyond recommended limits will cause damage that might not be seen. This damage adds up and can lead to sudden pipe failure.

UFE 10,000T : These pipes have a tested bend radius of 230 ft (70.1m), measuring a 90 degree bend, whether during entry and exist or when turning, required 230 ft (70.1m) or forward distance and approximately 354 ft (54m) of pipe.

Notice: Bending pipe more sharply than recommended will damage pipe and cause failure over time.

Entry Pitch :

Entry Pitch is boring unit slope compared to slope of ground. Entry Pitch can be determined two ways :

1. Lay Pitch beacon on ground and read pitch. Lay pitch beacon on beacon on boring unit and read pitch. Subtract ground pitch from boring unit Pitch.

2. Measure from ground to front end of frame (A). Measure from ground to back end of frame (B). Subtract front measurement from back measurement to get rise.

Measure distance between front and back points to be turn (C). Divide rise by run and multiply by 100 to get pitch.

A Shallow entry pitch allows you to reach horizontal sooner and with less bending. Increasing entry pitch makes bore path longer and deeper.

Minimum Depth :

Because pipe must be bent gradually, entry pitch and bend limits determine how deep the pipe will be when it reaches horizontal.

To reduce depth, reduce entry pitch. To increase depth, increase entry pitch and set-back.

Entry Point :

Fore bore to be successful, first pipe must be straight. To prevent bending or staining pipe, position boring unit for straight entry.

Dig a small starting hole so first length bore into a vertical surface to help ensure first pipe is not bent.