HOW TO CHOOSE THE CENTRALIZER
We would like to share with you why we’ve run centralizers. How can you choose centralizer ?
You might ask yourself : why do we use a centralizer to keep the casing centered in the hole or parent casing. So that cement can flow over the entire annulus when your semen is set in the right places. You can achieve an effective semen sheath that promotes well bore integrity.
Five different centralizerS
Here you see a sample of five different centralizer designs.
All these for five and a half inch casing to be running eight and a half inch open hole. They represent two families both spring centralizers and rigid centralizers.
Let’s go through some of the differences centralizers with the bow spring design.Like these two are very common .
1) They have welded and non welded bow Springs .when these bows push against the wellbore, they push back to help center the pipe important considerations
2) When selecting a bow spring centralizer:the running forces and restoring forces. The running force contributes to the drag forces.
3)When running casing into the well and the restoring force dictates the centralizers ability to overcome forces pushing the casing off-center.
This centralizer has been the workhorse of the industry for many years. It has several welded bows. You should look for welded bows that use an automatic welding process. that gives you a will consistency
The centralizer has a hinge that can latch around the casing or coupling or stop collar. They pull the centralizer into the wellbore for ease of running in the hole. The hinge design itself is folded inward to be supported against the casing. The casing makes it more robust and stronger.
The ridge here is pressed into the end band. It creates a stronger end band and thereby a stronger centralizer. And also guides the centralizer through any restrictions and ease of running These centralizers are used in vertical and deviated wells. This style of centralizer is particularly useful in an open hole. sections could be oversize. Because the bows are larger than the planned hole size. The Vera form centralizer is a single piece centralizer.
The manufacturing process allows for athree-dimensional shape to achieve best performance. As you can see the bow width and the curvature can vary as well as the OD and the length.
This type of centralizer is available in two styles. One for passing through restrictions and opening up into an under inked hole section or standard bear form. In this case, the centralizer OD is the same as the drill hold ID. Thereby providing greatest standoff and zero running force to pass through restrictions.This design uses a proprietary joining process. The process is indistinguishable from the base metal.
The centralizer has run between stop collars. It is great for rotating applications. Because of its single piece construction, the Vera form centralizer has full tractability. The Rigid centralizers have blades ,but don’t flex under down hold conditions.This makes them rugged enough for deviated and horizontal well bores.Because their OD is smaller than the well board. there is some sacrifice and standoff. These types of centralizers are also good for rotating applications.
The spiral glid centralizer
The spiral glid centralizer is the most used rigid centralizer in the world. It has rounded hollow blades made with the controlled welding process. The blades glide and cut drag forces the spiral blade. The blade will also create some turbulence to optimize mud removal and displacement during cementing. This feature makes it suitable for vertical inclined and horizontal wells.
The hollow blades designed to collapse. If the casing becomes stuck in a restriction. the composite centralizer has tapered blades. It is lightweight compared to some metal rigid centralizers.
These centralizers have a lower coefficient of friction than steel centralizers. These work well in reach and deviated wells.The buyers should be careful when selecting the composite centralizer. The impact loading and wear characteristics of the material are understood.
This centralizer has blades welded to the exterior of the body for a completely solid construction.
Although the blades angle to help mud flow around the centralizer. notice the sharp edges on the blades and the aggressive angle which could cause excessive drag. these centralized are quite heavy as well.
We are not a big fan of this design but they are used. But we hope you found this explanation useful.If you’d like more information. please visit our website to see our centralizer application guide.