Centralizer is a kind of high-efficiency tool used to maintain the centering degree of casting pipes in cementing operation, and is one of the drilling tools that is preferred by petroleum companies.
Casing and cementing operations are very important to the stability of boreholes. Poor cementing quality will bring fatal problems to oil and gas wells. The key to success is to correctly understand the reasonable configuration of centralizers.
Improper or a little centralizer configuration will greatly increase the friction when running casing pipes. The casing pipe and collar will increase the friction, so it requires additional down force to run the casing pipe in place. The keyway will cause the formation of grooves on the side wall, resulting in the leakage and even the jamming of drilling tools. The above problems can be avoided by reasonable centralizer configuration and obtaining the best centering effect. In many wells, side wall erosion often occurs, which requires a lot of extra cement.
Reasonable casing centralizer configuration is the cheapest and most reliable way to run the casing pipe to the bottom of the well and obtain the best cementing quality. If the centralizer is not used for cementing, the casing pipe will be attached to the side wall. Because of the high fluidity of cement, it will flow along the route with the least resistance, and the cement will not flow to the bottom of casing pipe in horizontal section. The casing pipe cannot be centered simply by rotation. The casing pipe will not suspend in the upper sidewall, so we cannot guarantee that the casing pipe will remain in good suspension condition at the bottom of the well which is up to 5km deep.
The role of cement is to keep the borehole stable and avoid gas invasion and corrosion. After fracturing, poor cementing operations will cause production loss, formation contamination and early workover, which will reduce the production and increase costs, while the use of centralizers can improve rather than shorten the life of oil and gas wells.