A drilling stabilizer is a piece of down hole equipment used in the bottom hole assembly (BHA) of a drill string. It mechanically stabilizes the BHA in the borehole in order to avoid unintentional sidetracking, vibrations, and ensure the quality of the hole being drilled. It is composed of a hollow cylindrical body and stabilizing blades, both made of high-strength steel. The blades can be either straight or spiraled, and are hard faced for wear resistance.

Several types of drilling stabilizers are used in the oilfield today. While integral stabilizers (fully machined out of a single piece of steel) tend to be the norm, other types can be used, such as :

Replaceable sleeve stabilizer

where the blades are located on a sleeve, which is then screwed on the body. This type can be economical when no repair facilities are available close to the well being drilled and air freight has to be used.

Welded blades stabilizer

where blades are welded onto the body. This type is usually not advised on oil wells due to the risks of losing blades, but is regularly used when drilling water wells or on low-cost oilfields.

Also they could classified by their sleeves appearances and applications:
  1. Integral blade stabilizers(alloy steel): The spiral blades machined to provide maximum mud circulation.

  2. Stabilizer Mandrels : one pieces stabilizer sleeve mandrels

  3. Standard stabilizer sleeves : Rig replaces able units to help solve the problems of logistics when drilling in remote4 control.

  4. Barrel stabilizer sleeves : Designed to overcome the logistics difficulties normally.

  5. Heavy duty stabilizers sleeves: Designed to overcome the logistics difficulties associated with hard formation drilling in remote areas.

  6. Welded blade stabilizers: Used in the B.H.A for drilling soft to medium hard formation holes.

Usually 2 to 3 stabilizers are fitted into the BHA, including one just above the drill bit (near-bit stabilizer) and one or two among the drill collars (string stabilizers).

The blades are spiral milled in either left hand (L.H) or right hand  (R.H) in three main configurations:
Wide open: 150°  to 210°
Open :over 210° to 270°
Tight :over 270° to  360°

Blade diameters are ground to maximum of   1/32" under gauge on all hole sizes.


Here is some Pages Releated to this topic.