![]() In contrast, horizontal wells are ideally suited for these aquifers. ![]() In coastal or island communities, saltwater intrusion is a classic problem ? overpumping of the ?bubble? of potable water floating above a brackish or saline layer can cause irreparable damage through saltwater intrusion. HORIZONTAL DIRECTIONAL DRILLING VIDEO INSTALLMultiple wells, spaced at intervals and pumped at lower rates may provide a more continuous water supply, but are costly to install and maintain. Production of viable quantities of water from these formations can be challenging with vertical wells ? drawdown at even minimal pumping rates quickly exhausts the supply adjacent to the well, with the potential for damaging the formation. In some locales, the best groundwater reserves are situated in thin, sinuous buried stream channels. Many coastal or island communities, and some desert municipalities, must tap thin, shallow or vertically constrained perched aquifers for their water supply. In contrast, a network of vertical wells drilled to intercept the same volume of aquifer would require multiple rig setups, multiple wellheads, and hundreds of feet of non-productive riser casing. ![]() Once at depth however, the length of the screened interval is only limited by the rig capacity and local geology.Ī shallow, 50-foot deep well takes approximately 200 feet to achieve the target depth, but may be hundreds or even in excess of 1,500 feet in length. This surface penetration is offset between four and five times the target depth of the well. A horizontal well only needs to penetrate the overburden above the aquifer once (twice in the case of a double-ended well). For wells that extend beneath fragile or protected ecosystems, this means that no roads must be constructed for installation or ongoing access for maintenance.Īnother advantage of horizontal wells is their favorable screen to riser ratio. They require only limited surface disruption ? from a single, relatively small construction footprint, screens may be set tens of feet deep, while extending laterally for hundreds of feet in length, with no other effect on the surface environment. This article explores some of the more challenging water development scenarios, and how HDD can provide a viable solution.Ĭommon to all of these water resources solutions are their utilization of HDD?s key benefits. Vertical drilling is likely to remain a mainstay of the water industry, but HDD can be advantageous in some cases. More recently, HDD has been applied to water resources development projects, with promising results. The shallow depth capabilities, combined with the ability to steer a bore beneath obstacles along a predetermined path has greatly expanded the ability to access contaminated zones with appropriate treatment technologies.? In the mid 1990s, this technology was adapted to install wells for the remediation of contaminated industrial sites, military bases, gas stations and other locations. Shallow HDD bores typically are started from the surface at an acute angle, and are guided to a subsurface or remote surface target using sophisticated electronics packages that enable the driller to navigate and steer the drill along a desired path. Unlike the deep directional bores used in oil exploration and production, which can extend thousands of feet deep, shallow HDD is performed from just a few feet to a few hundred feet beneath the ground surface. Meanwhile, a relatively new technology, shallow horizontal directional drilling (HDD) for utility and pipeline installation, has evolved rapidly over the past three decades. Even the venerable cable tool rig is still used for this purpose in some locales. Despite mechanic?al advancements in advancing a borehole, however, the extraction technology has remained the same: drilling and casing a vertical bore that intercepts a water table. Shovels gave way to cable tool rigs in the early 1800s and mechanical improvements incrementally led to current well-drilling technology, typically rotary drive rigs with automated casing drivers. ![]() The technology for extracting groundwater from subsurface resources hasn?t advanced appreciably since drillers abandoned shovels and buckets for mechanized well drilling rigs. ![]()
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