Extended Reach Drilling(ERD) is directional drilling

Directional drilling

Directional drilling is the practice of drilling non-vertical wells. It can be broken down into three main groups: Oilfield Directional Drilling, Utility Installation Directional Drilling Directional drilling (or slant drilling) is the practice of drilling non-vertical wells. It can be broken down...

 of very long horizontal wells. The aims of ERD are:

1. to reach a larger area from one surface drilling location, and
2. to keep a well in a reservoir for a longer distance in order to maximize its productivity and drainage capability.

Today’s challenges in ERD are hole cleaning, managing the mechanical loads on the drill string and managing downhole pressure. There is even the cost issue to consider.

Definition

Early ERD-well definitions related wells to those that exceeded some step-out/vertical-depth ratio (often 2:1). However, for most highly deviated wells in deepwater environments, this definition clearly does not fit. Some methods have evolved to categorize wells according to their stepout within different vertical-depth ranges. ERD wells then can be described conveniently as shallow, intermediate, deep, and ultradeep. Other variants are associated with operating in deep water and high-pressure/high-temperature environments. Currently, there is no generally accepted ERD-well definition.

What exactly determines a well to be "extended reach" varies over time and location with the development of technologies and of experiences .

• On 28 January 2011 the world’s longest borehole was drilled at the Odoptu field, Sakhalin-I
  Sakhalin-I
  The Sakhalin-I project, a sister project to Sakhalin-II, is a consortium to locate and produce oil and gas on Sakhalin Island and immediately offshore, in the Okhotsk Sea, from three fields: Chayvo, Odoptu, and Arkutun-Dagi....
  
   with a measured total depth of 12,345 meters (40,502 ft) and a horizontal displacement of 11,475 meters (37,648 ft).
• Maersk Oil Qatar had the previous world record in a well with a measured depth of 40,320 ft (12,290 m) including a horizontal reach of 35,770 ft (10,900 m) in the Al Shaheen Field offshore Qatar.

New developments and innovations

New technologies emerge that claims to be pushing the existing boundaries of ERD. One of these is the Reelwell Drilling Method, a drilling method solving problems for challenging wells, particularly suited for long reach wells. This innovation aims at multiplying the distance drilled by conventional ERD methods.

There are several companies offering Extended Reach Drilling services, operations and equipment;

• Reelwell
• Merlin ERD

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