Originally, horizontal drilling was restricted to formations which were hard to produce because they had low permeability like shale and chalk , or were nearing exhaustion, or where conventional drilling produced too much water too quickly and not enough oil and gas. French oil firm Elf Aquitaine drilled the first modern horizontal wells in southwest France and in the Mediterranean off Italy in the early s. BP used horizontal wells at Prudhoe Bay in Alaska to minimize unwanted water and gas intrusions into its oil reservoir.
But from , the technique started to proliferate. Most of the early wells were drilled into the Austin Chalk in Texas at the Giddings Field and Pearsall Field, as many as in alone. By August , horizontal wells were producing 70, barrels per day of oil in Texas. But from , a much more ambitious and successful program was begun. By the end of , Petroleum Development Oman had drilled more than horizontal wells. In the early s, more than 50 horizontal wells were also drilled in Abu Dhabi, and Saudi Arabia also embraced the technique for its depleted Watra oil field in the Neutral Zone shared with Kuwait, according to Schlumberger.
The tremendous potential of horizontal drilling was recognized right from the start. That prediction turned out to be premature - but only by a few years. The number of oil and gas wells being drilled horizontally overtook the combined number of vertical and directional slanted wells for the first time in March link. Two-thirds of oil and gas wells are now drilled horizontally, according to the weekly rig counts published by oilfield services company Baker Hughes.
It took roughly a decade of experimentation, between and , to work out how to combine horizontal drilling and hydraulic fracturing in the Barnett shale in Texas, an approach pioneered by George Mitchell at the eponymous Mitchell Energy.
From , however, the number of wells drilled horizontally has grown exponentially. In fact, horizontal wells have largely replaced vertical and directional wells, on account of their greater reservoir contact and efficiency.
It would be short-sighted to ignore a technique which offers improved drainage in typical reservoirs and more discrete compartments in complex reservoirs, while helping reduce gas and water coning. Commentators often write about the shale revolution as if it began in Texas in the early years of the 21st century. But no revolution emerges from nowhere. The fuse for the shale revolution was lit at least at decade earlier. 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. 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.
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. 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 in. The depth should be less than 30 ft. The dry system is suitable only for small-diameter pipelines typically less than 4 in. 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, psi for cutting the soil, while mini-HDD uses water pressure less than 4, 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 ft for 1. So, to understand where we're going, it's vital to know how far our industry has come. The true history of horizontal directional drilling began long before HDD itself. While HDD proper didn't emerge as a viable technology in construction until the s, the seeds of innovation were sown well before that. Before that first job could occur, a number of technological advancements had to be made.
In addition to being a machinist and welder, Melsheimer designed and invented many tools and techniques that would form the basis for horizontal directional drilling. In particular, he pioneered the slurry, or "wet," boring process — the foundation of all modern-day HDD.
With much of the same spirit, Fred's sons, Ted and Dick Melsheimer , started working at the company in , joining full-time in Together, they developed the DynaMole self-propelled hydraulic boring machine, which made longer bores possible. In , Dick and Ted obtained a patent on the DynaMole. Part of that patent was the method of pulling a utility in behind a backreamer during horizontal drilling. Years later, because he had this claim as part of the patent, Dick was able to successfully stop a company from being able to charge a licensing fee to all contractors who used horizontal directional drilling.
Ultimately, this saved the industry millions of dollars. In the s, another figure emerged who would be crucial to the birth of HDD.
When Martin Cherrington watched a gas line installed using a handheld air drill, he got an idea for guided drilling. Eventually, this led to Cherrington custom building an early version of a directional drilling rig in to complete road boring jobs. Additionally, there were several developments from the mids through the lates that would form the basis for transmitter location systems.
The technology used for sewer line tracking and cable locating systems provided these building blocks, which would be strengthened years later through the addition of transistors and microprocessors.
It took some time, but the project was a success. In many ways, this opened the door for more projects and advancements. The construction industry saw this, along with Dick Melsheimer's numerous developments, as proof that horizontal directional drilling was a viable method of underground utility installation that caused minimal disruption to the surroundings.
In the late 70s, Dick Melsheimer, working with Goldac Co. This locator served as a direct ancestor to modern-day walkover transmitter location systems, a core component of horizontal directional drilling equipment.
While this technology, as well as Cherrington's contributions, still wouldn't be commonplace for quite some time, they were key stepping stones toward a thriving HDD industry.
The breakthroughs of the 70s led directly into the major technological developments of horizontal directional drilling equipment in the s — and that ball hasn't stopped rolling. In , Dick Melsheimer started a new company called Borzall Equipment to focus on producing long-lasting reamers, bits and other HDD tools.
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