Li-Ming Zhang

New water-soluble ampholytic polysaccharides for oilfield drilling treatment: a preliminary study

New water-soluble ampholytic polysaccharides with carboxybetaine groups, which were prepared by grafting the zwitterionic monomer 2-(2-methacryloethyldimethylammonio)ethanoate onto hydroxyethyl cellulose, have been tested for their properties as a multifunctional drilling-mud additive regarding clay hydration inhibition and mud rheological control. For the ampholytic polysaccharides investigated, an increase in carboxybetaine groups results in an enhanced inhibitive ability and the pH of the medium has an effect on the inhibition. A strong viscosifying efficiency for low-solid muds, especially for saline mud, has been observed.

Synthesis and characterization of new amphoteric graft copolymer of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methylacrylate

The graft copolymerization of sodium carboxymethylcellulose (NaCMC) with acrylamide (AM) and dimethylaminoethyl methylacrylate (DMAEMA) was conducted in an aqueous solution using ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylene diamine (TMEDA) as the initiator. The effects of various factors on grafting, such as temperature, pH, initiator concentration, and concentrations of AM, DMAEMA, and NaCMC were studied. The composition and thermal stability of the graft copolymers were characterized by infrared, elemental, and thermogravimetric analysis, and degradation activation energy and kinetic order were calculated. The relationship between its reduced viscosity and pH in aqueous NaCl was also investigated.

A Facile Approach to Incorporate Silver Nanoparticles into Dextran-Based Hydrogels for Antibacterial and Catalytical Application

Dextran hydrogel was prepared by the crosslinking reaction of dextran and N,N-methylenebisacrylamide in aqueous sodium hydroxide aqueous solution. Highly stable and uniformly distributed silver nanoparticles have been prepared using these hydrogel networks as a carrier via in situ reduction of silver nitrate without the addition of any reducing agent. The spherical silver nanoparticles with diameters of 20–30 nm were found to adopt a face centered cubic structure. The hydrogel hybrid with silver nanoparticles can be effectively employed as antibacterial and catalytic materials.

Synthesis and aqueous solution properties of hydrophobically modified graft copolymer of sodium carboxymethylcellulose with acrylamide and dimethyloctyl(2-methacryloxyethyl)ammonium bromide

The hydrophobically modified water-soluble graft copolymer of sodium carboxymethylcellulose with acrylamide and dimethyloctyl(2-methacryloxyethyl)ammonium bromide has been synthesized using potassium persulfate and dimethylaminoethyl methacrylate as initiators in aqueous solution. The structure and composition of the graft copolymer were characterized by infrared spectrum and elementary analysis. Molecular weight was determined by gel permeation chromatography. The solubility and viscosity of the graft copolymers in aqueous solution were investigated, as a function of copolymer concentration, added salt, temperature, shear rate, and surfactant. In addition, the intermolecular hydrophobic association in aqueous solutions in the presence of added salt and surfactant was demonstrated through the retention time from gel permeation chromatography measurement.

Novel modified lignosulfonate as drilling mud thinner without environmental concerns

A novel modified lignosulfonate was prepared by crosslinking lignosulfonate acid with naturally occurring tannin extract in the presence of formaldehyde and further chelating with ferrous ions. The modification reactions were verified by IR analyses and its performances as polymeric thinning agent for aqueous bentonite mud in oilfields were evaluated. Compared with commonly used FeCr–lignosulfonate thinner, the chrome-free modified lignosulfonate without environmental concerns has better thinning ability and can offer better resistance to elevated temperature, as well as matched tolerance to high salinity. In addition, its thinning mechanism was discussed by means of adsorption isotherms, zeta potential measurements, and SEM observations.

Inhibition of water‐soluble cationic cellulosic polymers to clay hydration

The inhibition of water-soluble cationic graft terpolymers of hydroxyethylcellulose with the vinyl monomers dimethyldiallylammonium chloride and acrylamide to the hydration of water-sensitive clay in oilfields was investigated by clay hydration-swelling tests, XRD analyses, zeta-potential measurements, and SEM observation. It has been shown that grafting enhances the hydration-inhibition effectiveness and the performances of these cationic cellulosic polymers are strongly dependent on their cationicity, relative molecular weight, and solution concentration.

Studies on new ampholytic cellulose derivative as clay-hydration inhibitor in oil field drilling fluid

A new ampholytic cellulose derivative (CAD) was prepared by grafting acrylamide and dimethyldiallylammonium chloride on carboxymethyl cellulose (CMC). The performance of CAD applied as a clay-hydration inhibitor in oil field drilling fluid was examined; the results showed that CAD had a hydration inhibitive property with better mud-making performance for low-solid mud. The mechanisms of the CAD inhibition of clay hydration were studied. The inhibiting-hydration performance of CAD was found to depend not only on cation, anion content, and molecular weight, but also on the cation–anion association in CAD chains.

New amphoteric graft copolymers of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methacrylate: Aqueous solution properties

The solubility and viscosity properties of new amphoteric graft copolymers of sodium carboxymethyl cellulose with acrylamide and dimethylaminoethyl methacrylate in aqueous solutions were investigated by turbidimetry and viscometry experiments. The factors investigated include the pH of the medium, the composition of the graft copolymer, the concentration and type of added salt, temperature, aging time, and the addition of organic solvent. Unlike conventional copolymers, these graft copolymers have unique solution behavior due to the presence of both acidic and basic groups along the macromolecular backbone. In addition, their solution properties are closely related to their conformations and are partially controlled by the net electrical charge and the ionic strength.

Preparation and anti-clay-swelling ability of new water-soluble cellulose derivatives containing quaternary ammonium groups

New water-soluble cellulose derivatives containing quaternary ammonium groups were prepared by the heterogeneous reactions of hydroxyethyl cellulose with a quaternary chlorohydrin and characterized by reaction parameters and infrared analyses. The dependence of the heterogeneous reaction on the different affecting factors was studied. The cellulose derivatives obtained were investigated for their property as the water-soluble polymer for inhibiting the swelling of water-sensitive clay in oilfields. Based on the kinetic curves for clay hydration swelling, a mathematical model that relates linear clay expansion as a function of hydration rate and hydration equilibrium constant was developed.

Novel modified cellulosic polymers as drilling fluid additives with improved properties

Novel modified cellulosic polymers with amphoteric character were prepared by grafting 2-dimethylaminoethyl methacrylate (DM) and 4-vinylbenzene sulphonic acid sodium salt (VB) onto sodium carboxymethylcellulose (NaCMC), and characterized by IR and composition analyses. Their properties as drilling-fluid additives in oilfields were investigated with respect to shale inhibition, filtration control and viscosity enhancement. It is found that the grafting of DM enhances the shale-inhibition effectiveness and that the grafting of VB increases the tolerances to salt and temperature. Different from commonly used anionic and cationic polymeric additives, the modified cellulosic polymer with suitable structural parameters has both good shale-inhibition and mud properties. © 1999 Society of Chemical Industry