Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Synthesis and Application of Comb-type Salt-resistant Polycarboxylate Dispersant

Xuewen Yang1, Hongtao Liu1, Kangwei Ao2, Lei Yang2, Tianyi Zhang2, Siqi Tu2, Haipeng Xin2, Zhongtao Yuan1
PetroChina Tarim Oilfield Company,Korla, Xinjiang, China
2
CNPC Tianjin Boxing Engineering Science & Technology Co., Ltd.,
Laboratory of Cementing Technology, CNPC Key Laboratory of Drilling Engineering,Laboratory of Cementing Technology, National Engineering Laboratory of Petroleum Drilling Technology,Binhai New Area, Tianjin, China
1ABSTRACTmixing and placement. Rheology is a measure of both the resistance toflow and a reduction in the resistance to flow under pressure. Adding
comb-type polycarboxylate dispersant can reduce friction and pressureduring pumping, enhance turbulent flow with reduced pumping rate,
and allow operators to mix densified cement slurries. Comb-type
polycarboxylate dispersant can also be used to reduce the pressureexerted when cement passes through unconsolidated sands, depleted orweak formations, which may prevent leakage circulation.

The comb-type salt-resistant polycarboxylate dispersant (CSPD) was
developed to solve the shortcomings of the poor dispersibility of thecurrent dispersant in saline cement slurry. CSPD has salt-to-saturation
resistance, poor thixotropy, and the use in saturated saline water
prepared slurry can still meet the requirements of the standard fordispersant in freshwater systems. It can effectively disperse saltcontaining high-density cement slurry, conventional density and lowdensity cement slurry. CSPD has successfully solved the problem thatthe slurry cannot be prepared and cannot be constructed due to the rapid
hydration of the saline slurry which was prepared with NaCl in thehigh-temperature environment. It also solved the core problem in thenano-based low-density cement slurry. Besides the application in antichanneling cement slurry led to good dispersion performance. It has
been successfully applied in Halfaya Oilfield, Missan Oilfield, Dagang
Oilfield and Tarim Oilfield, effectively improving the fluidity ofcement slurry, ensuring the displacement efficiency, improving thecementing quality, and ensuring the cement ring sealing ability.

SYNTHESIS AND CHARACTERIZATION OF CSPD
The design criteria of CSPD
a. The molecular structure is comb-shaped, and the active groups on themain chain are mainly -COOH and -SO3H, which can be effectively
anchored on the surface of cement particles.
b. The side chain also contains hydrophilic active groups and the chain
segment is relatively long. Macromonomers form a solvation layer on
the surface of the cement and can form a network structure. The combshaped flexible adsorption on the surface of cement particles has
obvious steric hindrance. Combined with the electrostatic repulsion
generated between the anions of the main chain, it plays a role at thesame time, forming a larger three-dimensional repulsion effect.
c. The use of non-hydrolyzable monomers ensures good structure
retention under high temperature conditions, thereby ensuring its
temperature resistance.
d. Add salt-resistant monomer and use its sulfonic acid group toimprove salt-resistancee. Control the molecular weight in a moderate range.

KEY WORDS: Cementing; slurry; dispersant; comb-type
INTRODUCTION
During the drilling process, complex formations such as high-pressure
saline formations, large salt paste formations, or water-sensitive
formations were encountered (Chang, 2013; Gao, 2014; Hou, 2013;
Wei, 2014) both in China and overseas in Iraq, Kazakhstan, Uzbekistan,
Indonesia and other countries (Chen, 2015; Gai, 2011; Zhou, 2011; Zou,2015). In addition, in sea and coast operations, it is often attempted todirectly prepare cement slurry with seawater (Chen, 2013; Lu, 2014).
Due to the high solid content and high salt content, salt/seawater
cement slurry exhibits poor fluidity, strong thixotropy and high initialconsistency.
Comb-type polycarboxylate dispersant is a kind of high performancedispersant which is used to help modify slurry rheology for easier

The synthesis of CSPDThe CSPD was synthesized by free radical polymerization of acrylicacid,hydrophilicmacromoleculeA,
2-acrylamide-2methylpropanesulfonic acid (AMPS), sulfonic acid anchoring monomer
B and rigid monomer C. The addition of acrylic acid and monomer B574