Additives play an important role in the cementing of oil well.
There are several types of cement additives that have been developed to allow cement to be used in many different oil and gas wells.
best cement types
To formulate the right cement mortar for any cementing job, the right additive must be chosen and the right amount added.
Additives have different functions and are broadly categorized as accelerators, inhibitors, expanders, fluid loss agents, dispersants and many others.
Each broad classification includes different classes of additives designed to perform approximately the same function in cement mortar design.
However, there are some additives under each major type that are commonly used in the design of cement slurries for cementation operations in oil and gas wells.
When cementing wells, Portland cement systems are designed for temperatures ranging from below freezing in permafrost regions to 350°C (662°F) in thermal reclamation and geothermal wells.
best cement features
Additives are available to improve the properties of the oil well slurry and achieve successful placement between the casing and the geological formation, developing rapid compressive strength and good drilling insulation over the life of the well.
According to Cowan and Eoff, additives are commonly added to cement formulations to disperse cement particles, adjust curing time under conditions of temperature and pressure in the well, control liquid leaching losses from cement slurries during and after placement, and compensate for shrinkage as the cement hardens and hardens, improves the interface between the cement and casing and controls the flow and migration of formation fluids in the cement column during curing.
best cement specifications
Several types of cement additives have been developed to allow Portland cement to be used in many different oil and gas wells.
Each main type contains different types of additives designed to perform approximately the same function in cement mortar design.
However, there are some additives under each major type that are commonly used in the design of cement slurries for cementation operations in oil and gas wells.
This document provides an overview of the broad classification of oil well additives, focusing on the additives commonly used in the cementation of oil and gas wells.
Additives and some common types The degree of hydration when mixing water with cement can be changed with the help of chemical additives.
Additives are chemicals and materials mixed in a base cement mortar to change the performance of cement.
Due to the inherent nature of the base cement and the demands placed on the cement casing throughout the life of the well, the performance characteristics of the cement slurry are modified to address the specific and unique conditions of each well.
Many of the additives used today are organic polymers formulated specifically for use in well cementation.
Typical chemical additives for oils and cement
- Accelerators
The accelerator is a chemical additive used to accelerate the natural reaction rate between cement and water, which reduces the cement thickening time, increases the early strength of the cement and saves the expensive drilling time.
Cement slurries used in shallow wells where temperatures are low require accelerators to shorten the "wait for cement (WOC)" time before resuming drilling.
In deep wells, higher temperatures improve the curing process and accelerators may not be necessary.
Accelerators do not increase the maximum compressive strength of the cement, but rather promote the rapid development of strength.
- Retarders
These are chemical additives used to reduce the hydration rate of cement.
Concrete commonly used in well applications does not have a sufficient fluid life for use at bottom hole circulation temperatures (BHCTs) above 100 F (38 C).