Competitive adsorption between an AMPS®‐based fluid loss polymer and Welan gum biopolymer in oil well cement

Abstract

Water-soluble 2-acrylamido-2-methylpropane sulfonic acid (AMPS V R )-based copolymers are commonly used to provide water retention (fluid loss control) for oil well cement slurries. Here, the fluid loss performance of a CaAMPS V R -N,N-dimethylacrylamide copolymer (CaAMPS V R -co-NNDMA) in the presence of Welan gum, an anionic microbial biopolymer produced by anaerobic fermentation using Alcaligenes ATCC 31555 bacteria was investigated at 80 C. Welan gum is used to control unwanted free water development at the surface of the cement slurry. The effectiveness of CaAMPS V R -co-NNDMA fluid loss additive (FLA) solely relies on its high adsorption onto the positively charged surfaces of cement hydrates. Adsorption of the FLA is, however, perturbed by Welan gum. This anionic polysaccharide competes with CaAMPS V R -co-NNDMA for adsorption sites on the cement surface. This effect is surprising because in cement pore solution, Welan gum exhibits a much lower specific anionic charge amount than CaAMPS V R -co-NNDMA. The reason is that Welan gum possesses carboxylate functionalities, which are much stronger anchor groups than the sulfonate groups present in CaAMPS V R -co-NNDMA. The superiority of the carboxylate groups regarding their affinity to the mineral surface, which possesses insufficiently coordinated Ca atoms is confirmed by a higher calcium binding capability for Welan gum than for the FLA. Thus, Welan gum can reduce effectiveness of CaAMPS V R -co-NNDMA as fluid loss agent by preventing its adsorption or through displacement of already adsorbed FLA molecules from the surface of cement. In multiadmixture systems, which are commonly used in oil well cement, concrete or mortars, competitive adsorption between different additives for surface sites can negatively impact the performance of these additives. Understanding the reasons behind can help to develop more effective admixture systems.

Copolymer SJ-1 as a Fluid Loss Additive for Drilling Fluid with High Content of Salt and Calcium

“…To make sure the fluid loss additive has an excellent ability of absorption, the monomer with strong absorption groups, such as amino-group, are introduced [12,13]. To make sure the additive has an excellent ability of salt tolerance, the monomers with stable group which is not sensitive to the cation, such as -SO 3 − , are introduced [14][15][16].…”

Function Synergy of Cross-Linked Cationic PVA Polymer to AMPS-Type Fluid Loss Additive Used for Cement-Based Material

“…Thus, the ZETA potential analysis test was utilized. [5,34]. As per the test results (Table 7), the FLA A additive showed strong absorption ability to Ca 2+ and originally with a negative ZETA potential property, and PVAGB was designed to show a relatively positive ZETA potential and would impose the chemically absorbed behavior of AMPS units on FLA A chains.…”

“…In particular, the FLA A/PVAGB mixture polymer additive solution mass ratio of FLA A to PVAGB was 5 : 2. Then, the Ca 2+ additive (CaCl 2 ) of 0.6 g/L may be added to FLA A and FLA A/PVAGB polymer solutions to obtain an equivalent Ca 2+ content in cement-based materials [34]. A NaOH agent was utilized to adjust the pH value to simulate the cement slurry chemical environment.…”

Synthesis and performance of fluid loss agents based on different acrylamide monomers

“…2-Acrylamido-2-methyl-propane sulfonic acid (AMPS) with a vinyl group is commonly used as monomer of synthetic FLA due to good thermal stability and low sensitivity to cations (Plank et al 2006(Plank et al , 2010Ma et al 2014). Related researchers developed a series of FLA by copolymerization of AMPS with other monomers to control fluid loss of cement slurry (Peng et al 2010).…”