TY - GEN
T1 - Incremental improvements in 50:50 poz cementing yields enhanced properties and cost-effective application
AU - Fasesan, O. A.
AU - Heinze, L. R.
AU - Walser, D. W.
N1 - Publisher Copyright:
© Copyright 2005, Society of Petroleum Engineers Inc.
PY - 2005
Y1 - 2005
N2 - For nearly 50 years, admixtures of 50:50 Class H (or Class C): Pozzalon with 2% bentonite have functioned effectively worldwide as lightweight slurries for situations where heavier completion cements posed a risk of exceeding low fracture gradients in a particular wellbore. Pozzolanic materials are lightweight, and effectively combine with calcium hydroxide that is liberated during the hydration of Portland cement. Historically, the 2% bentonite has been utilized to assist in the specification of relatively high water-To cement ratios, and therefore lighter slurry density, without the generation of excessive free water as the cement progresses though the setting process. Though the bentonite has fulfilled the role quite well, it has two disadvantages: first, its presence in typical cement slurries reduces the effectiveness of a given concentration of most commercially available fluid loss additives. Second, while the 2% (by weight of cement) volume may seem of no consequence, the shipping costs associated with moving tons of the material over a long period of time can be significant. A project was undertaken to determine whether or not there were other commercially available materials that could substitute for bentonite and yield improved slurry qualities at the same or reduced cost. Extensive testing of 50:50 slurries revealed that small quantities of sodium metasilicate (on the order of 0.5% by weight of cement) could effectively replace bentonite. Free water was controlled to the same degree, and a synergy with a commonly available fluid loss additive was discovered, allowing either a) less total fluid loss additive for a given fluid loss control tolerance, or, b) better fluid loss control for a given concentration of fluid loss additive. The testing is summarized, and relative economics associated with the systems are discussed.
AB - For nearly 50 years, admixtures of 50:50 Class H (or Class C): Pozzalon with 2% bentonite have functioned effectively worldwide as lightweight slurries for situations where heavier completion cements posed a risk of exceeding low fracture gradients in a particular wellbore. Pozzolanic materials are lightweight, and effectively combine with calcium hydroxide that is liberated during the hydration of Portland cement. Historically, the 2% bentonite has been utilized to assist in the specification of relatively high water-To cement ratios, and therefore lighter slurry density, without the generation of excessive free water as the cement progresses though the setting process. Though the bentonite has fulfilled the role quite well, it has two disadvantages: first, its presence in typical cement slurries reduces the effectiveness of a given concentration of most commercially available fluid loss additives. Second, while the 2% (by weight of cement) volume may seem of no consequence, the shipping costs associated with moving tons of the material over a long period of time can be significant. A project was undertaken to determine whether or not there were other commercially available materials that could substitute for bentonite and yield improved slurry qualities at the same or reduced cost. Extensive testing of 50:50 slurries revealed that small quantities of sodium metasilicate (on the order of 0.5% by weight of cement) could effectively replace bentonite. Free water was controlled to the same degree, and a synergy with a commonly available fluid loss additive was discovered, allowing either a) less total fluid loss additive for a given fluid loss control tolerance, or, b) better fluid loss control for a given concentration of fluid loss additive. The testing is summarized, and relative economics associated with the systems are discussed.
UR - http://www.scopus.com/inward/record.url?scp=85088206139&partnerID=8YFLogxK
U2 - 10.2523/94327-ms
DO - 10.2523/94327-ms
M3 - Conference contribution
AN - SCOPUS:85088206139
SN - 9781613990094
T3 - Society of Petroleum Engineers - SPE Production Operations Symposium 2005, POS 2005
BT - Society of Petroleum Engineers - SPE Production Operations Symposium 2005, POS 2005
PB - Society of Petroleum Engineers
T2 - SPE Production Operations Symposium 2005, POS 2005
Y2 - 16 April 2005 through 19 April 2005
ER -