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How to Choose the Right Centralizer for Your Well


hi I’m Doug with Weatherford and I’d
like to share with you why we’ve run centralizers and how you can choose the
right centralizer you might ask yourself why run centralizer centralizers keeps
your casing centered in the hole or parent casing so that cement can flow
over the entire annulus when your cement is set in the right places you can
achieve an effective cement sheath that promotes well bore integrity here you
see a sample of five different centralizer designs all of 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 among them centralizers with the bow
spring design like these two are very common they have welded and non welded
bow Springs when these bows are pushed against the wellbore they push back to
help center the pipe important considerations when selecting a bow
spring centralizer are the running forces and restoring forces the running
force contributes to the drag forces 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 that pulls 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 that makes it more robust and stronger the ridge here is
pressed into the end band that 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 typically used in vertical and deviated
wells this style of centralizer is
particularly useful in an open hole sections
could be oversized because the bows are normally larger than the planned hole
size the Vera form centralizer is a single piece centralizer the
manufacturing process allows for a three-dimensional shape to achieve
optimum 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 maximum standoff and
zero running force while also providing the flexibility to pass through
restrictions this design uses a proprietary joining process that is
indistinguishable from the base metal the centralizer has run between stop
colors and is great for rotating applications because of its single piece
construction the Vera form centralizer has full traceability rigid centralizers
like these three have blades that don’t flex under down hold conditions
this makes them rugged enough for highly 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 glider centralizer is the most widely used rigid centralizer in the
world it has rounded hollow blades made with the controlled welding process the
blades glide smoothly and minimize drag forces the spiral 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 also the
hollow blades are designed to collapse if the casing becomes stuck in a
restriction the composite centralizer has tapered blades and 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 highly deviated wells the buyers should be careful when selecting
the composite centralizer that the impact loading and wear characteristics
of the material are clearly understood this centralizer has blades welded to
the exterior of the body for a completely solid construction
although the blades are angled 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 I’m not a big fan of
this design but they are commonly used I hope you found this explanation useful
if you’d like more information please visit our website to see our centralizer
application guide or call your local Weatherford well construction
representative

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