Directional Drilling:
Horizontal well drilling, which is a method of deviating the well until it is at, or close to a 90° angle from the vertical in order to drill out sideways and along a specific layer of rock. The trajectory of a well-bore starts vertically then steers horizontally at depth for thousands of feet. This allows increased contact between the well and the reservoir to increase productivity. Horizontal Drilling also provides access to reservoirs that are too thin to be fully accessed by vertical drilling.

Multilateral Drilling:
A single well-bore creates a trunk and then many branches stem from it, increasing production from a single drilling site. Multilateral drilling increases the contact area and allows for many branches to produce from the same well. These can be horizontal, curved slightly to one side, or turned sharply to form a J-type well. Multilateral drilling can occur in either new or existing oil and gas wells and typically includes two laterals. The main benefit of using this drilling approach is the increased efficiency and reduced cost of tapping multiple reservoir locations from a single point.

Extended Reach Drilling (ERD):
To figure out if the well is considered an ERW, calculate the ratio of horizontal departure to vertical depth. If the depth ratio is greater than 2, the well is considered an Extended Reach Well (ERW). An ERW can be relatively long and deep, short and shallow, or something in between. The benefit of Extended Reach Drilling is the increase in efficiency by exposing the open hole to long sections of the reservoir rock, or by crossing through multiple reservoirs in one long well-bore. It is expensive and risky but it is sometimes the best option available. With advances in technology, these wells are getting longer and longer as we get better at overcoming the challenges of managing down-hole pressure, managing and controlling the mechanical loads on the drill string, and hole cleaning.