Squeeze cementing represents a critical process in the oil and gas industry, where a cement slurry is squeezed through perforations in casing to create a seal in specific locations, bridging undesired gaps. It is a common misconception that the cement penetrates the pores of the rock. Instead, the cement slurry dehydrates against the formation walls, forming a seal cement filter cake. It must be clear that cement does not infiltrate the pores of the rock. Given that cement slurries have particles with a mean size ranging from 20 to 50 microns, the permeability of the formation must be between 2-100 darcies for cement grains to penetrate the formation successfully.
To achieve a successful oil well cementing and ensure zonal isolation in oil well cementing, efficient mud displacement is crucial. Inadequate mud removal can lead to problems like cement channeling, permitting the intrusion of hydrocarbons and communication between permeable zones. The following factors are essential for ensuring a good cement bond:
Cementing operations in the oil and gas industry are a critical component of well construction and integrity. Proper casing and cementing hardware play a crucial role in ensuring the successful execution of these operations. In this article, we will explore the various equipment used in cementing operations, including guide shoes, float collars, centralizers, cement wiper plugs, and multi-stage collars.
casing and cement hardware
Guide Shoes and Float Shoes: Continue reading
Cementing in the oil and gas industry involves a meticulous process, and cementing additives play a crucial role in fine-tuning the properties of cement slurries. These additives are carefully selected to control slurry density, rheology (flow behavior), fluid loss, and to impart specialized characteristics for effective cement placement in diverse downhole conditions. Let’s explore the various categories of additives used in cementing:
1. Accelerators: Accelerators are chemicals employed to expedite the thickening process of a cement slurry and enhance early strength development. Typically used in conductor and surface casing applications to reduce waiting-on-cement time (WOC), common accelerators include calcium chloride (CaCl2), sodium chloride (NaCl), and seawater. Continue reading
Oil well cement adheres to API Specification 10 and is categorized into eight classes, labeled A to H, based on its specific properties. Among these, Class G and Class H serve as foundational well cements that can be employed alongside accelerators and retarders to accommodate a broad spectrum of well depths and temperature conditions. One notable distinction between these two classes lies in their particle size, with Class H being notably coarser than Class G.