Schlumberger

Technical Paper: Engineered Cement Set Control Additive—Solution for a Long Standing Cementing Challenge

Society: SPE
Paper Number: 101332
Presentation Date: 2006
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Abstract

Cementing long zones with a single slurry system is a very challenging problem that has been known in the industry for many years. The main difficulty is related to the large temperature differential between the bottom and the top of the long cement column. The cement slurry is typically designed to have a thickening time to allow placement at the bottom hole circulating temperature. However, the same slurry when exposed to the much lower temperature that exist at the top of the cement column may not set for several days. This can lead to long waiting on cement resulting in rig non productive time or in certain cases can lead to well integrity problems.

Another known problem in the industry is setting of cement plugs in an environment where the bottom hole temperature is not well known. This scenario may exist while setting unplanned kickoff plugs or plug and abandonment of wells. The thickening time of slurries retarded with conventional additives are sensitive to temperature and therefore uncertainties in bottom hole temperature may lead to excessive setting time or premature setting, both of which can be costly.

A new generation of engineered cement set control (ECSC) additive has been developed to resolve the problems mentioned above. The ECSC additive provides thickening times that are almost independent of temperature thus allowing efficient and reliable cementing of long cement columns, where there is a large temperature differential between the top and the bottom. The ECSC additive will also minimize setting problems in situations where the bottom hole circulating temperature is not known accurately.

This paper presents the results of a successful field application of the ECSC additive to cement long casing sections in fields in the Middle East. The well designs require the reliable isolation of long casing/liner sections in order to safeguard well integrity and meet well construction objectives.

Field implementation, results including logs from the wells are presented.

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