Horizontal Directional Drilling
Content
Horizontal Directional Drilling Technique (HDD) The Horizontal Directional Drilling technique (HDD) is on its developmental stage at the moment. Directional drilling operation was unheard of in the past now belongs to everyday scene on any job site.
HDD is defined as “A steerable system for the installation of pipes, conduits, and cables in a shallow arc using a surfaced launched drilling rig. Traditionally HDD is applied to large scale crossings such as rivers in which a fluid filled pilot hole is drilled without rotating the drill string, and this is then enlarged by a wash over pipe and back reamer to the size required by the product.” (Trenchless Data Service 2000).
This technology has been in existence since the 1970’s. It is currently an efficient, safe, cost effective method for highway bores and is the current industry standard for trenchless technology for bores between 2 and 48-inch diameters and 600 ft to 1800 ft in length.
The economic savings is primarily for the utility. HDD should provide less damage to the right of way, since it requires smaller bore pits or open trenches. It would allow the utility to be placed under trees, rivers, concrete drives, sidewalks, pavements and buildings as well as roadways. It should provide for improved safety of the traveling public as most of the work can be done off right of way, more quickly and with less manpower and equipment.
It should improve maintenance since the HDD installed facilities are generally deeper, thus reducing the chances the lines will be hit by casual. maintenance crews. Additionally, it would reduce the number of relocations for future roadway expansion, and should provide some additional protection from rupture. However, that is not always necessarily the case as many of the applicants want to go the minimum required depth required. Consideration should be given to the overall safety, aesthetic quality, costs and difficulty of construction and maintenance of both the utility facility and the highway.
THE HISTORY OF HDD Martin Cherrington first conceived horizontal directional drilling in the 1960’s. He first realized the value of underground drilling when he and another contractor were given the same
job: lay down telephone lines in Los Angeles. The only difference was that Cherrington was using an open trench method while the other contractor was using drilling to lay down cables. That contractor arrived two weeks after Cherrington yet managed to finish two weeks before him. This led Cherrington to believe there was merit in looking at underground drilling methods. In 1964 Cherrington founded Titan Contractors, which specialized in utility road boring. It was an opportune time for the company’s formation because of a building boom in Sacramento and a recent “beautification” decree from the First Lady, Lady Bird Johnson. The decree was instated to clean up America by getting rid of utility lines which were an eyesore and hazardous during seismic and extreme weather events. As a solution, Sacramento proposed placing all utilities underground. Despite a favorable environment and HDD’s merits, however, other, more familiar, tunneling technologies like jack and bore and auger boring were usually preferred. One of the main problems was the lack of control when drilling. It was often very difficult to make a straight bore, and the drill bit would resurface in unexpected places (like the middle of the road). Cherrington realized a solution when an engineer from P G& E invited him to consider a project for placing a gas line underneath the Pajaro River. The project would require drilling underneath the river, and the variability of the drill bit’s direction would make it challenging. To find a solution, Cherrington experimented with angled bores on a similar river, trying several different angles. He observed that the steeper the angle of the bore, the greater the achieved distance. This relationship between angle and distance helped prove that with “optimum entry angle, proper drilling techniques and the right downhole tool assembly” (Cherrington) HDD could be used to cross a river. Since then, familiarity with HDD has increased, and it has become a much more routine method for projects requiring a non-evasive boring solution.
INTRODUCTION TO HDD Horizontal directional drilling (HDD) is a common practice for installing utilities and pipelines under roads or railroad tracks. It is an ideal technology because it does not require large excavation pits nor does it greatly interfere with traffic. When drilling the initial borehole, the drill can be easily tracked and its path altered unlike other trenchless technologies such as jack and bore. HDD is also versatile as it can be used for large diameter pipelines and pipelines spanning a large distance.
Horizontal Directional Drilling (HDD) is a trenchless installation technique developed to install pipe under natural or manmade obstacles, especially waterways and highways. Today directional drilling is utilized not only for crossings, but also for parallel installations along the right-of-way as an alternative to digging trenches. HDD is utilized for the installation of gas, water and sewer mains; chemical pipelines; and electric and communications conduits.
The main advantages: 1. Production and technical aspect • Capability of trenchless construction, repairing and cleaning underground pipelines: - under rivers, gullies, forest areas; in specific soils (rock, quicksand); - in guarded areas of high voltage overhead lines, main gas, oil pipelines; - under conditions of urban housing system if a line is planned to build under motorways, street railways, roads, public gardens and parks; • Shortening of terms and volumes of organizational and technical agreements before start to work; it’s possible as there’s no need to stop all kinds of transport and/or block motorways and railways; • Significant shortening of the time for work performance due to using high technological drilling complexes; • Significant shortening of heavy machinery and workers number using for laying pipelines; • Shortening of accident risks, and as a result they guaranty to keep a pipeline in operating state for long; • There’s no need to have external power supply during the drilling due to complete machine autonomy; • There’s no need to reduce water level under conditions of high ground water. 2. Financial and economic aspect • Shortening of construction budget due to cuts of the time for work performance and costs on using extra workers and heavy machinery. • Minimizing costs on power supply for drilling complexes due to their economy. • There is no need to restore damaged roads and railways, green plantations and urban infrastructure. • Shortening of maintenance costs on control and restoring pipelines during their maintenance. 3. Socio-economic aspect • Saving landscape and ecological balance of sites where the works are carried out, exclusion of an anthropogenic impact on the flora and fauna, erosion of banks and bottom deposits of basins. • Minimizing negative impact on people’s living conditions in the area where the works are carried out.
Importance of HDD - Basic HDD Process The range of application includes all pipe construction measures within the bounds of gas, district heating and drinking water supply, the installation of pressure lines for sewers as well as cable protection pipes for television or telephone cables, traffic routing systems, emergency call boxes or low, medium, high voltage and optical fibre cables.
Usefulness of Trenchless Technology to various subsurface networks Today we are looking at an unprecedented growth of urban settlement leading to an equally explosive growth in the demand of water supply. This supply either is made through new lines or existing old lines.
Water:
Sewer & Pollution Control:
When we look at new lines the development process is to lay new lines. Do we want unrestricted open excavations to lay such lines in already developed areas? When we look at old lines there is a high possibility that due to ageing or other factors they might have developed leaks leading to heavy transmission losses. A major portion of the Unaccounted for Water (UfW) comes from these leaks. Would we relish to loose a substantial amount of treated water in ground due to leaking mains? Sewer lines again face the similar fate. The only difference in this case is that the infiltrated sewerage gets mixed-up with the precious ground water making it bad. Will we continue to have the same or want to rectify the situation?
Power & Telecom:
Today the power transmission and distribution lines are being transferred from their over-ground locations to subsurface locations. Will we want open cut excavations and potholes on the roads to develop these networks ?
Oil & Gas:
Initiation of Directional Drilling operations in India was due to the demand of Oil & Gas sector. There are numerous requirements where Trenchless alone can provide effective solutions to network development and management challenges.
This provides solution for building up sub-surface pipe network in an inaccessible / difficult area where open cut trenching will not work out, without loss of any direction as well as dimension. The accuracy and quality remain prime objective. The safety and environmental balancing are the most important. Obviously the machines used in this process and the technology applied has to be well understood by the planning and executing personals. The installation technique is extremely protective towards the environment, causing no ecological damage at all. Minimal damage to the area is only caused within the vicinity of the unit. Several reasons also speak for the application of the directional technique in central town areas. These mainly concern the construction costs, construction periods, permission procedures, soil movement, surface restoration and the traffic, compared to open trenching methods. The normal course taken by the drilling operation is described in the following:
1. Planning, preliminary survey 2. Selecting the drilling units and drilling tools 3. pilot bore and detection 4. Reaming(s) or upsizing bore(s) 5. Pulling in the pipe Basically, the drilling unit consists of three main system components 1. Drill rig / drilling tools 2. Bentonite mixing system with a two-chamber system and in some cases a recycling system 3. Hydraulic power unit for driving the Bentonite mixing unit
A well planned HDD operation includes preliminary survey of the bore path area to determine existing external lines and the soil condition. The choice of the drilling unit depends upon the bore length, the diameter of the pipe to be installed and the soil quality. Keeping up a certain bore path and gradient course is the main problem of the pilot bore, when the fluid assisted technique fails because of mechanical soil resistance. To overcome this, high thrust and pulling forces are required, reaching the limits of maximum capacity in many cases. Application of Bentonite might relieve the pilot bore and the pipe traction. But experience has proved that the technical and economical advantages of Soft Boring can hardly take effect in difficult soil conditions with coarse grained components and considerable rock inclusions or building rubble deposits.
The drilling unit is equipped with the shattering force of a displacement hammer. It is the combination of fluid assisted drilling with an impact unit which makes propulsion and steerability possible in difficult soil qualities up to grade 5, sometimes even grade . The high demands and expectations towards the quality of the drilling job waiting to be done require precise detection and steering. Detection is carried out following the transmitter-receiver principle. One operator follows the course of the bore head all the time. All measured values are taken to protocol, directional corrections are passed on to the machine operator via radiophone. On arrival, the bore head is replaced with an upsizing head (backreamer). One or more intermediate upsizing bore follows, or else the pipe is pulled in at once. Pipes made of plastic, steel and cast iron can be pulled in, single or bundled. When pulling in plastic pipes (especially for gas and potable water pipes), the permissible pulling forces must not be exceeded. On the client's demand, the pulling forces applied to the pipe have to be measured and taken to protocol. The control over the process of Horizontal Directional Drilling is an extremely important aspect. As the drilling head is invisible during the drilling, the uncontrollable drilling can have unexpected consequences. Therefore during Horizontal Directional Drilling the location systems are used to control the process of drilling. The exact position of the pipe installed can be determined after completing the drilling job. Every HDD project is unique and will have unique elements, conditions and requirements. There are several manufacturers and a wide range of HDD equipment. A well versed knowledge will build up confidence and safe and systematic work.
Before work starts, soil properties and its constitution are studied closely, existing underground
communications are removed; all necessary work authorizations are received and selective soil probing is made. All the results have a primary meaning for choosing the path and tactics of bore hole laying. Special attention should be devoted to an optimal location of drilling equipment on a building site and ensuring safety working conditions for workers and other people. The HDD method is comprised of a four stage process:
1. Pilot hole drilling 2. Pilot hole enlargement 3. Pipeline pulling 4. Final stage 5. HDD location system STATE REGULATIONS : In USA, State regulations for HDD exist in some states but need further clarification. It is currently prohibited under state highways for bores over 6 inches. Bores of greater size must be done by the jack and bore method. The manual is being re-written and will include a provision for an HDD option, but it will not define the parameters under which approval can be granted. In India, the decisions like depth, pilot-hole diameter and manhole with covers are well defined. The contractor or engineer has to follow those while planning. Besides these, different agencies involved in the total process also impose certain laid down rules which need to be strictly followed.
THE certificate COURSE
SCTIT offers specialized structured training courses on trenchless technologies. These training programs are technology specific and tailored to the needs and interests of the user of HDD technology.
The broad objectives of this Program are: To offer need based and tailor made academic program for the specific need of supervisory level manpower engaged in HDD work. To upgrade and modernize the technical know-how of those engaged in Operation and maintenance related activities apart from fresh candidates desirous of taking up careers in HDD. To provide better industry-education linkage by matching learners educational needs to industry needs by collaborating with professionals and other technical institutions. This couse will offer :
To learn from a well-respected specialist and leading expert on Drilling technology Will receive comprehensive course documentation To learn about safety, obligations & regulations. Learn about industry best practice and guidance Learn from Open discussions, will engage and share between each other Hands-On Case Studies from the trainer's experience On-hand practice Certificate will be issued AREAS COVERED :
- Latest Advances in Horizontal Drilling - Special Drilling Procedures - Directional well planning - positioning and coordinating systems - Directional Profiles - Synthetic Drilling fluids - Fluid Design - Measurement-While-Drilling - Logging While Drilling - Survey calculation methods - Calculations of drilling trajectory - Directional well path design - Horizontal well planning - Hole cleaning - Wellbore stability - Well integrity assessment - Well productivity measurement
HDD is defined as “A steerable system for the installation of pipes, conduits, and cables in a shallow arc using a surfaced launched drilling rig. Traditionally HDD is applied to large scale crossings such as rivers in which a fluid filled pilot hole is drilled without rotating the drill string, and this is then enlarged by a wash over pipe and back reamer to the size required by the product.” (Trenchless Data Service 2000).
This technology has been in existence since the 1970’s. It is currently an efficient, safe, cost effective method for highway bores and is the current industry standard for trenchless technology for bores between 2 and 48-inch diameters and 600 ft to 1800 ft in length.
The economic savings is primarily for the utility. HDD should provide less damage to the right of way, since it requires smaller bore pits or open trenches. It would allow the utility to be placed under trees, rivers, concrete drives, sidewalks, pavements and buildings as well as roadways. It should provide for improved safety of the traveling public as most of the work can be done off right of way, more quickly and with less manpower and equipment.
It should improve maintenance since the HDD installed facilities are generally deeper, thus reducing the chances the lines will be hit by casual. maintenance crews. Additionally, it would reduce the number of relocations for future roadway expansion, and should provide some additional protection from rupture. However, that is not always necessarily the case as many of the applicants want to go the minimum required depth required. Consideration should be given to the overall safety, aesthetic quality, costs and difficulty of construction and maintenance of both the utility facility and the highway.
THE HISTORY OF HDD Martin Cherrington first conceived horizontal directional drilling in the 1960’s. He first realized the value of underground drilling when he and another contractor were given the same
job: lay down telephone lines in Los Angeles. The only difference was that Cherrington was using an open trench method while the other contractor was using drilling to lay down cables. That contractor arrived two weeks after Cherrington yet managed to finish two weeks before him. This led Cherrington to believe there was merit in looking at underground drilling methods. In 1964 Cherrington founded Titan Contractors, which specialized in utility road boring. It was an opportune time for the company’s formation because of a building boom in Sacramento and a recent “beautification” decree from the First Lady, Lady Bird Johnson. The decree was instated to clean up America by getting rid of utility lines which were an eyesore and hazardous during seismic and extreme weather events. As a solution, Sacramento proposed placing all utilities underground. Despite a favorable environment and HDD’s merits, however, other, more familiar, tunneling technologies like jack and bore and auger boring were usually preferred. One of the main problems was the lack of control when drilling. It was often very difficult to make a straight bore, and the drill bit would resurface in unexpected places (like the middle of the road). Cherrington realized a solution when an engineer from P G& E invited him to consider a project for placing a gas line underneath the Pajaro River. The project would require drilling underneath the river, and the variability of the drill bit’s direction would make it challenging. To find a solution, Cherrington experimented with angled bores on a similar river, trying several different angles. He observed that the steeper the angle of the bore, the greater the achieved distance. This relationship between angle and distance helped prove that with “optimum entry angle, proper drilling techniques and the right downhole tool assembly” (Cherrington) HDD could be used to cross a river. Since then, familiarity with HDD has increased, and it has become a much more routine method for projects requiring a non-evasive boring solution.
INTRODUCTION TO HDD Horizontal directional drilling (HDD) is a common practice for installing utilities and pipelines under roads or railroad tracks. It is an ideal technology because it does not require large excavation pits nor does it greatly interfere with traffic. When drilling the initial borehole, the drill can be easily tracked and its path altered unlike other trenchless technologies such as jack and bore. HDD is also versatile as it can be used for large diameter pipelines and pipelines spanning a large distance.
Horizontal Directional Drilling (HDD) is a trenchless installation technique developed to install pipe under natural or manmade obstacles, especially waterways and highways. Today directional drilling is utilized not only for crossings, but also for parallel installations along the right-of-way as an alternative to digging trenches. HDD is utilized for the installation of gas, water and sewer mains; chemical pipelines; and electric and communications conduits.
The main advantages: 1. Production and technical aspect • Capability of trenchless construction, repairing and cleaning underground pipelines: - under rivers, gullies, forest areas; in specific soils (rock, quicksand); - in guarded areas of high voltage overhead lines, main gas, oil pipelines; - under conditions of urban housing system if a line is planned to build under motorways, street railways, roads, public gardens and parks; • Shortening of terms and volumes of organizational and technical agreements before start to work; it’s possible as there’s no need to stop all kinds of transport and/or block motorways and railways; • Significant shortening of the time for work performance due to using high technological drilling complexes; • Significant shortening of heavy machinery and workers number using for laying pipelines; • Shortening of accident risks, and as a result they guaranty to keep a pipeline in operating state for long; • There’s no need to have external power supply during the drilling due to complete machine autonomy; • There’s no need to reduce water level under conditions of high ground water. 2. Financial and economic aspect • Shortening of construction budget due to cuts of the time for work performance and costs on using extra workers and heavy machinery. • Minimizing costs on power supply for drilling complexes due to their economy. • There is no need to restore damaged roads and railways, green plantations and urban infrastructure. • Shortening of maintenance costs on control and restoring pipelines during their maintenance. 3. Socio-economic aspect • Saving landscape and ecological balance of sites where the works are carried out, exclusion of an anthropogenic impact on the flora and fauna, erosion of banks and bottom deposits of basins. • Minimizing negative impact on people’s living conditions in the area where the works are carried out.
Importance of HDD - Basic HDD Process The range of application includes all pipe construction measures within the bounds of gas, district heating and drinking water supply, the installation of pressure lines for sewers as well as cable protection pipes for television or telephone cables, traffic routing systems, emergency call boxes or low, medium, high voltage and optical fibre cables.
Usefulness of Trenchless Technology to various subsurface networks Today we are looking at an unprecedented growth of urban settlement leading to an equally explosive growth in the demand of water supply. This supply either is made through new lines or existing old lines.
Water:
Sewer & Pollution Control:
When we look at new lines the development process is to lay new lines. Do we want unrestricted open excavations to lay such lines in already developed areas? When we look at old lines there is a high possibility that due to ageing or other factors they might have developed leaks leading to heavy transmission losses. A major portion of the Unaccounted for Water (UfW) comes from these leaks. Would we relish to loose a substantial amount of treated water in ground due to leaking mains? Sewer lines again face the similar fate. The only difference in this case is that the infiltrated sewerage gets mixed-up with the precious ground water making it bad. Will we continue to have the same or want to rectify the situation?
Power & Telecom:
Today the power transmission and distribution lines are being transferred from their over-ground locations to subsurface locations. Will we want open cut excavations and potholes on the roads to develop these networks ?
Oil & Gas:
Initiation of Directional Drilling operations in India was due to the demand of Oil & Gas sector. There are numerous requirements where Trenchless alone can provide effective solutions to network development and management challenges.
This provides solution for building up sub-surface pipe network in an inaccessible / difficult area where open cut trenching will not work out, without loss of any direction as well as dimension. The accuracy and quality remain prime objective. The safety and environmental balancing are the most important. Obviously the machines used in this process and the technology applied has to be well understood by the planning and executing personals. The installation technique is extremely protective towards the environment, causing no ecological damage at all. Minimal damage to the area is only caused within the vicinity of the unit. Several reasons also speak for the application of the directional technique in central town areas. These mainly concern the construction costs, construction periods, permission procedures, soil movement, surface restoration and the traffic, compared to open trenching methods. The normal course taken by the drilling operation is described in the following:
1. Planning, preliminary survey 2. Selecting the drilling units and drilling tools 3. pilot bore and detection 4. Reaming(s) or upsizing bore(s) 5. Pulling in the pipe Basically, the drilling unit consists of three main system components 1. Drill rig / drilling tools 2. Bentonite mixing system with a two-chamber system and in some cases a recycling system 3. Hydraulic power unit for driving the Bentonite mixing unit
A well planned HDD operation includes preliminary survey of the bore path area to determine existing external lines and the soil condition. The choice of the drilling unit depends upon the bore length, the diameter of the pipe to be installed and the soil quality. Keeping up a certain bore path and gradient course is the main problem of the pilot bore, when the fluid assisted technique fails because of mechanical soil resistance. To overcome this, high thrust and pulling forces are required, reaching the limits of maximum capacity in many cases. Application of Bentonite might relieve the pilot bore and the pipe traction. But experience has proved that the technical and economical advantages of Soft Boring can hardly take effect in difficult soil conditions with coarse grained components and considerable rock inclusions or building rubble deposits.
The drilling unit is equipped with the shattering force of a displacement hammer. It is the combination of fluid assisted drilling with an impact unit which makes propulsion and steerability possible in difficult soil qualities up to grade 5, sometimes even grade . The high demands and expectations towards the quality of the drilling job waiting to be done require precise detection and steering. Detection is carried out following the transmitter-receiver principle. One operator follows the course of the bore head all the time. All measured values are taken to protocol, directional corrections are passed on to the machine operator via radiophone. On arrival, the bore head is replaced with an upsizing head (backreamer). One or more intermediate upsizing bore follows, or else the pipe is pulled in at once. Pipes made of plastic, steel and cast iron can be pulled in, single or bundled. When pulling in plastic pipes (especially for gas and potable water pipes), the permissible pulling forces must not be exceeded. On the client's demand, the pulling forces applied to the pipe have to be measured and taken to protocol. The control over the process of Horizontal Directional Drilling is an extremely important aspect. As the drilling head is invisible during the drilling, the uncontrollable drilling can have unexpected consequences. Therefore during Horizontal Directional Drilling the location systems are used to control the process of drilling. The exact position of the pipe installed can be determined after completing the drilling job. Every HDD project is unique and will have unique elements, conditions and requirements. There are several manufacturers and a wide range of HDD equipment. A well versed knowledge will build up confidence and safe and systematic work.
Before work starts, soil properties and its constitution are studied closely, existing underground
communications are removed; all necessary work authorizations are received and selective soil probing is made. All the results have a primary meaning for choosing the path and tactics of bore hole laying. Special attention should be devoted to an optimal location of drilling equipment on a building site and ensuring safety working conditions for workers and other people. The HDD method is comprised of a four stage process:
1. Pilot hole drilling 2. Pilot hole enlargement 3. Pipeline pulling 4. Final stage 5. HDD location system STATE REGULATIONS : In USA, State regulations for HDD exist in some states but need further clarification. It is currently prohibited under state highways for bores over 6 inches. Bores of greater size must be done by the jack and bore method. The manual is being re-written and will include a provision for an HDD option, but it will not define the parameters under which approval can be granted. In India, the decisions like depth, pilot-hole diameter and manhole with covers are well defined. The contractor or engineer has to follow those while planning. Besides these, different agencies involved in the total process also impose certain laid down rules which need to be strictly followed.
THE certificate COURSE
SCTIT offers specialized structured training courses on trenchless technologies. These training programs are technology specific and tailored to the needs and interests of the user of HDD technology.
The broad objectives of this Program are: To offer need based and tailor made academic program for the specific need of supervisory level manpower engaged in HDD work. To upgrade and modernize the technical know-how of those engaged in Operation and maintenance related activities apart from fresh candidates desirous of taking up careers in HDD. To provide better industry-education linkage by matching learners educational needs to industry needs by collaborating with professionals and other technical institutions. This couse will offer :
To learn from a well-respected specialist and leading expert on Drilling technology Will receive comprehensive course documentation To learn about safety, obligations & regulations. Learn about industry best practice and guidance Learn from Open discussions, will engage and share between each other Hands-On Case Studies from the trainer's experience On-hand practice Certificate will be issued AREAS COVERED :
- Latest Advances in Horizontal Drilling - Special Drilling Procedures - Directional well planning - positioning and coordinating systems - Directional Profiles - Synthetic Drilling fluids - Fluid Design - Measurement-While-Drilling - Logging While Drilling - Survey calculation methods - Calculations of drilling trajectory - Directional well path design - Horizontal well planning - Hole cleaning - Wellbore stability - Well integrity assessment - Well productivity measurement
