In oil field equipment,Cementing tools are an important part of the oil and gas drilling process, and play an important role in ensuring the efficiency and safety of cementing operations. Casing centralizers are an important part of cementing tools, which can ensure the smooth completion of oil and gas wells.
The purpose of a casing centralizer is to facilitate running casing to the desired depth and to assist in centering the casing in the wellbore. One of the main objectives of centralizing a casing string is to facilitate a good cementing, thereby isolating fluids from different zones.
1.centralizer oil and gas for casing
The purpose of a casing centralizer is to facilitate running casing to the desireddepth and to assist in centering the casing in the wellbore. One of the mainobjectives of centralizing a casing string is to facilitate a good cementingthereby isolating fluids from different zones.
Composition and working principle of casing centralizer
The casing centralizer mainly includes: the centralizer body, the spring sheet (or the supporting component) and the connecting component.
- 1. Centralizer body: The main part of the centralizer has a certain strength and rigidity, and can withstand the test of the complex environment downhole. On the outer wall of the centralizer itself, a limit hoop is usually fixing to limit the position of the centralizer.
- 2. Spring sheet (or support component): It is an important component of the centralizer oil and gas, which can play a supporting and positioning role. The spring sheet is evenly distributing around the centralizer itself, and adapts to casings of different diameters through elastic deformation. For the integral casing standoff tool, the middle part of the centralizer tube is evenly distributing with arc-shaping support plates protruding outward. Which also play a supporting and positioning role.
- 3. Connecting component: It is using to connect the centralizer to the casing to ensure that the centralizer can be lowering into the well with the casing during drilling.
3.Working principle of casing centralizer:
The centralizer adapts to the diameter change of the casing through the elastic casing standoff toolcenter of the wellbore. When the casing encounters a shrinkage of the wellbore or a change in the formation, the spring sheet (or supporting component) of the centralizer will be compressing. And deformed to adapt to the change in the diameter of the casing. While generating a reverse support force to push the casing to the center of the wellbore and maintain the stability of the casing. The centralizer can also guide the casing to be lowering along a predetermining trajectory to prevent. The casing from deviating from the designed wellbore trajectory.
4.Different Types of oil well Casing Centralizers and Their Applications
1. Bow spring centralizer
High-performance bows provide maximum standoff in multiple locations of the annulus, providing the best possible conditions for primary cement to achieve zonal isolation.
All centralizer sizes have been testing. And validating to meet American Petroleum Institute (API) 10D requirements, providing reliability and durability during operations.
Non-welded design can withstand most wellbore environments, providing operational flexibility.
Bow configurations are available in various heights and sizes suitable for most applications and providing a variety of bow configurations for special applications.
Size is available from 3 ½”to 30”
2. Tuborlizer bow spring centralizer
All centralizer sizes have been testing and validating to meet American Petroleum Institute (API) 10D requirements.
Equipped with right or left handed deflector fins which contributes to a high-quality primary cement job.
Size is available from 5 ½”to 30”
3. One-piece bow spring centralizer
One-piece bow spring centralizer is made of steel plate cutted by laser,then rolling for forming after heattreatment. There is a welded line on the body. Under newest manufacturing technique, the one- piece bow spring centralizer is made of seamless pipe, totally non- welding design. It has much better performances.
The one-piece construction means no weak points making it ultra-high-strength and outstanding reliability.
The centralizer oil and gas offers zero start and running forces, lower frictional drag.
It is designed specifically to replace a solid body type centralizer for casing running applications and severe well geometries when run in horizontal, S-type, J-type or extended-reach well designs.
Size is available from 4 ½”to 13 3/8”
4. Semi-rigid centralizer
The Semi-Rigid Centralizer outside strips are heaving, which can be contracting by a certain pressure. So that it can be preventing in the next to the hole of the hole to get stuck, to ensure that the normal into the well.
Compared with the spring bow centralizer, the semi-rigid centralizer has obvious advantages. Which has the advantages of simple structure, safe and reliable, high strength, convenient operation and so on. Can be widely using in straight wells or high angle well casing construction operations, in vertical wells if cementing requirements of rotating casing to improve displacement efficiency. Then semi-rigid spiral wellbore centering device is the only choice. The semi-rigid centralizer compare with the rigid centralizer has obvious advantages of simple structure, strong adaptability and can be compressing.
Size is available from 4 ½”to 13 3/8”
5. Rigid centralizer Roller centralizer
The rigid centralizers are generally constructing integral to add greater strength and are held in place by high loads top collars or set screws.
The tools are designing to improve cement flow while promoting maximum standoff from the borehole.
Provide both straight blade and spiral blade.
Size is available from 4 ½” to 20”
6. Composite centralizer
The Roller Centralizer consists of rigid body, on which machined spiral blades or straight.
There are modified alloy steel, fully heat treating rollers fixed on each blade Roller casing centralizers are mainly used for big high roller, high deviating wells and horizontal wells, to center casings.
Low torque and drag allows for rotation and reciprocation, providing improved mud displacement and cement job.
Size is available from 4 ½” to 20
7.Hydraulic bow spring centralizer
Suited for horizontal wells、directional wells Original O.D. is small which ensures the safety of running casing. The centralizers have strong restoring force after expanding and significantly improve the centering degree of the casing in horizontal wells.
Have strong pressure resistance with same inner diameter of the casing The bows can not return after expanding because of the anti-return structures.
Plenty sets of O-rings are equipping between body and hydraulic cylinder to get high reliability.
Stop collars limit the movement of centralizers over the pipe and are manufacturing to withstand high axial forces.
Three standard designs are available.
