Horizontal Directional Drilling Crossings: Understanding How They Work

Horizontal directional drilling (HDD) is a set of technologies used to generate improved production from subterranean oil and gas wells. The most common use of HDD is to complete wells in places where it is impossible or desirable to build a traditional vertical well. The HDD process involves drilling a vertical borehole in the surface, then following the path of a horizontal well up to and through the formation. The horizontal portion is drilled with a diameter typically greater than that of the vertical well borehole. In this way, the horizontal wellbore can be placed deeper into the formation than a traditional vertical well would have been.

In modern HDD wells, the horizontal portion has a diameter typically no less than that of the vertical wellbore and maybe three times larger. The vertical wellbore is usually much smaller, typically no larger than the borehole required for the horizontal portion. In this way, the amount of surface area needed for a single well is significantly reduced. In cases where the surface footprint of a horizontal well would have been much larger than that of a comparable vertical well, HDD can substantially reduce the environmental impact.

The horizontal portion of HDD wells may be any length, up to the entire length of the surface area desired for drilling. A typical application would be drilling a vertical wellbore on one side of a rock formation that is too deep for conventional vertical drilling. A horizontal well would then be drilled on the other side, and it would continue into the formation, eventually reaching the same depth as the vertical borehole. The wells are completed by injecting water or other fluids into the formation when drilling is completed.

hdd crossing

The most basic form of HDD, referred to as conventional HDD, is used when the target formation is relatively shallow. This method has been in use for over two decades and is still used in some areas where conditions are favorable for its use. It involves drilling a vertical wellbore and then drilling a perpendicular horizontal borehole. The two intersect at a special “X” shaped connection, and the horizontal portion is completed with a piston. The amount of fluid circulated out of the hole is controlled by a choke, and it is used to flush the formation as the borehole is drilled.

Crossing is a fundamental aspect of drilling

No one can deny that hdd crossing is a fundamental aspect of drilling operations. Any drill stem drilled into a formation must be followed by a directional portion, which is used to drill into the formation from the side. Horizontal drilling is commonly used to drill deeper into the formation. A horizontal well is drilled from the surface through a portion of the desired formation in the conventional HDD process. The gas well portion is completed as a vertical shaft well. The horizontal portion is drilled as a tube within the ground, usually to depths of 200 to 400 feet.

As global energy demands increase, so does the usefulness of HDD

No one can deny that the world needs more energy today than ever before. As global energy demands increase, so does the usefulness of HDD. This new technology is a great way to get more oil and gas from previously uneconomical wells.

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