Cement compositions containing flexible, compressible beads and methods of cementing in subterranean formations

Abstract

Cement compositions comprising flexible, compressible beads, processes for preparing such cement compositions, and methods of cementing in subterranean formations using such cement compositions. One or more flexible, compressible beads are mixed with the cement before pumping the cement into a well bore. The flexible, compressible beads are preferably composed of an elastomeric material such as a copolymer of methylmethacrylate and acrylonitrile; a terpolymer of methylmethacrylate, acrylonitrile, and dichloroethane; a styrene-divinylbenzene copolymer; and polystyrene. The flexible, compressible beads may be heated to expand the beads before mixing with the cement such that the ensuing cement composition will have a desired density. Non-flexible beads such as spherulites may also be added to the cement compositions.

Description

FIELD OF THE INVENTION This invention generally relates to cementing in subterranean formations penetrated by well bores. More specifically, the invention relates to cement compositions comprising flexible, compressible beads, and processes for making the compositions. BACKGROUND OF THE INVENTION Well cementing is a process used in penetrating subterranean zones (also known as subterranean formations) to recover subterranean resources such as gas, oil, minerals, and water. In well cementing, a well bore is drilled while a drilling fluid is circulated through the well bore. The circulation of the drilling fluid is then terminated, and a string of pipe, e.g., casing, is run in the well bore. The drilling fluid in the well bore is conditioned by circulating it downwardly through the interior of the pipe and upwardly through the annulus, which is located between the exterior of the pipe and the walls of the well bore. Next, primary cementing is typically performed whereby a slurry of ...

AI Technical Summary

Benefits of technology

"The present invention is about using flexible, compressible beads in cement compositions to improve the density and performance of the cement in well bores. The flexible beads made of materials like elastomeric materials, phenolic resins, and styrene-divinylbenzene copolymer can be heated to expand before mixing with the cement, and non-flexible beads like glass hollow beads and ceramic hollow spheres can also be added to the cement. This results in a cement composition with improved density and performance."

Problems solved by technology

Unfortunately, this method has the drawback that the addition of more water increases the cure time and reduces the strength of the resulting cement.

During the life of the well, the cement sheath is subjected to detrimental cyclical stresses due to pressure and temperature changes resulting from operations such as pressure testing, drilling, fracturing, cementing, and remedial operations.

Conventional hollow spheres suffer from the drawback of being brittle and fragile and thus often cannot sustain those cyclical stresses.

As a result, the cement sheath develops cracks and thus fails to provide zonal isolation for the life of the well.