e-ISSN:2319-9849 p-ISSN:2322-00 1 RRJCHEM | Volume 6 | Issue 4 | October, 2017 Research & Reviews: Journal of Chemistry INTRODUCTION Oil well cementing is an important process of drilling and completion operation. The cement slurry is placed between the casing and the drilled formation for adequate zonal isolation for the lifetime of the well [1] . Cementing operation is generally classifed into two categories as primary cementing and remedial cementing. Primary cementing is carried out immediately after drilling a section of a wellbore to hold casing and to isolate the formation from the wellbore. The design of primary cement slurry must be done with at most care as the lifetime of the well is primarily determined by the quality of primary cementing. Additives for this process should be selected based on several factors such as the well profle, temperature, pressure, acid-gas, etc. The designed cement slurry is pumped down and placed between casing and the geological formation. The set time is determined by the type of retarder and accelerator added in the slurry. The primary objective of having the primary cementing is to provide support and bond casing, zonal isolation to prevent fuid migration between formations, protect casing from corrosive environment, to act as a seal and a barrier to hold formation pressure and to provide protection for casing from drilling operations such as shock loads. Casing points and cementing stages are usually included in the well design itself. Therefore, the driller is always aware of the fact that the drilling must be phased for casing and cementing. However, there are situations where casing and cementing job becomes necessary to address a specifc drilling problem such as lost circulation. A successful cementing practices start with the design of effective cement slurries by adding additives to enhance or modify to achieve desired cement properties [2] . The additives added in cement are an integral part of the well design, construction and integrity. Therefore, a through lab testing must be carried for any new cement design or additive before applied the cement slurry in the feld. The lab testing includes compression test using UCA, setting time, etc. There are several additives included in the cement design for specifc applications. It is not possible to defne a general guideline for all situations for the concentration of additives required for the cementing job [3] . There are no standard guidelines to help drilling engineers and scientists in the effective design of optimal cement slurries to be used in different well sections. The selection of additives for cement design is based on the formation type, depth, temperature and pressure. Apart from commonly used additives for applications such as rheology, fuid loss control, and as retarders, specialty additives such Chemical Additives for Oil Well Cementing Abdullah Saleh Al-Yami, Jothibasu Ramasamy * and Vikrant Wagle Drilling Technology Team, EXPEC Advanced Research Center, Saudi Aramco, Dhahran 31311, Saudi Arabia Review Article ABSTRACT Cementing is an extremely important operation in oil well drilling to ensure the integrity of the well, prevent gas and oil migration for an extended period of time. Failure to have adequate cementing will lead to problems that are often catastrophic. Many a times, a revisit of cement integrity is required to diagnose any issues such as formation of micro fractures that will cause fuid or gas migration into the wellbore or to the surface. In such cases where there are issues found with cementing, a remedial cement job is necessary to address the issue. The design of a cement slurry is very important and should be done case by case to ensure trouble-free mixing before pumping and to achieve desired rheology, fuid loss control and thickening time after pumping downhole. A variety of chemicals have been used in cement for the application as retarders, fuid loss control additives, dispersants, gas migration prevention additives and expansion additives. Selection of right chemicals for cement design based on the well profle, off-set well data and other criteria such as temperature and pressure is the key to achieve maximum and long term beneft. There are several reports describing the different chemicals and their application in cementing. The objective of the review is to have an overview chemicals and their performance comparison in cement design based in mechanism of action Received date: 08/10/2017 Accepted date: 12/10/2017 Published date: 20/10/2017 *For Correspondence Jothibasu Ramasamy, Drilling Technology Team, EXPEC Advanced Research Center, Saudi Aramco, Dhahran 31311, Saudi Arabia. Tel: (713)432-4105 E-mail: jothibasu.ramasamy@aramco.com Keywords: Cementing Additives, Oil and Gas Wells, Primary Cementing, Remedial Cementing