Tailiang Zhang

Retention Behaviors of Hydrophobically Associating Polyacrylamide Prepared via Inverse Microemulsion Polymerization Through Porous Media

The retention behavior of hydrophobically associative polyacrylamide (HAPAM) with homogeneous composition in porous media was investigated. The results showed that HAPAM could exhibit different retention behavior, compared to PAM due to the existence of hydrophobic association group in HAPAM molecular frame. The critical association concentration could also be reflected by the curves between HAPAM concentration and retention amount. The retention amount of HAPAM was higher than that of polyacrylamide (PAM) and was smaller than the absorption amount of HAPAM. The retention mechanism was mainly controlled by adsorption mechanism.

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

A ternary copolymer of 2-acrylamide-2-methyl propane sulfonic acid (AMPS), acrylamide (AM), and allyl alcohol polyoxyethylene ether (APEG) with a side chain polyoxyethylene ether SJ-1 were designed and synthesized in this work. Good temperature resistance and salt tolerance of “” of AMPS, strong absorption ability of “amino-group” of AM, and good hydrability of side chain polyoxyethylene ether of APEG provide SJ-1 excellent properties as a fluid loss additive. The chemical structure of ternary copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The molecular weight and its distribution were determined by gel permeation chromatography (GPC). The API fluid loss of drilling fluid decreased gradually with the increasing concentration of NaCl and CaCl2 in the mud system. SJ-1 was applied well in the drilling fluid even at a high temperature of 220°C. Results of zeta potential of modified drilling fluid showed the dispersion stability of drilling fluid system. Scanning electron microscopy (SEM) analysis showed the microstructure of the surface of the filter cake obtained from the drilling fluid modified by SJ-1.

Synthesis and Properties of Aminoarylsulfonic Acid-Phenol-Formaldehyde Copolymer As Drilling Fluid Loss Reducer

Aminoarylsulfonic acid-phenol-formaldehyde copolymers were prepared via solution condensation polymerization in this study. FT-IR tests showed the molecular structure of resulting products successfully. The effects of parameters of copolymerization including the ratio of aminoarylsulfonic acid to phenol, the molar percentage of formaldehyde, temperature and time of reaction on properties of copolymer for API filtration control were investigated in detail, and the former two factors played more important roles. Furthermore, the API fluid loss was affected not only by the molecular weight of copolymer but also its content in drilling fluid, which was already determined at different temperature. Therefore, it can be concluded that such copolymer exhibit good properties in drilling fluid loss control at high temperature (230°C) compared with sulphonated methyl phenolic resin. The morphologies of filter cakes showed that clay particles dispersed more uniformly in copolymer-treated drilling fluid than in untreated ones.

Molecular dynamic simulations of the core–shell microsphere of nanosilica grafted by acrylamide acrylic acid copolymer PAMAA: study of its microstructure and interaction between microsphere and additives

Nanosilica grafted by acrylamide (AM) acrylic acid (AA) copolymer (PAMAA) is designed in this study to make a functional material, where nano-SiO2 provides the rigidity and strength and the copolymer the elasticity and flexibility. The resulting microsphere with a core–shell structure is able to enter, expand, shut off and be removed from deep layers of oilfields. Qualitative results can be easily obtained from normal experimental methods, but many quantitative relationships are still missing. To solve the problem mentioned above, molecular dynamic (MD) simulation is applied in this work to study the microstructure of microspheres and the interaction between microsphere and additives. Aqueous solutions (S1), as well as solutions with sodium dodecyl sulfate (SDS, S2), dodecyl trimethyl ammonium bromide (DTAB, S3), and alcohol ethoxylate (AEO, n = 3, S4) are built. The non-bond energy, radius of gyration (ROG) of microsphere, radial distribution function (RDF) for microsphere–additive pairs and mean square displacement (MSD) of polymer chains in these 4 different solutions are calculated at 325 K, 350 K and 375 K. The results show that addition of surfactants leads to a more stretched out polymer chain structure. The hydration effect and mobility of the polymer chain increase in both aqueous and surfactant solutions as temperature increases.

Synthesis and Acid Solution Properties of Two-head Group Viscoelastic Surfactant

Viscoelastic surfactant with two-head group was synthesized from monomers of lauric acid, hydroxyethyl ethylenediamine, and sodium chloroacetate in this study. The molecular structure of surfactant was proved by FT-IR. The results of viscosity property of fresh acid and spent acid showed that viscosity of former one decreased with increasing concentration of hydrochloric acid and it was mainly controlled by surfactant concentration and temperature. Maximum viscosity of spent acid appeared at pH = 4. Besides, viscosity of fresh acid and spent acid was affected by variation of carbon number of hydrophobic chain of surfactant or mixture of different carbon number of hydrophobic chain of surfactant.

Gemini Surfactant as a New “Green” Demulsifier for Treating Oilfield Emulsions

Abstract Surface tension and interfacial tension (IFT) were the key factors asso- ciated with the stability of crude oil emulsion. Investigation of interfacial tension behavior related with the demulsification of crude oil emulsions can have a great impact on the development of crude oil demulsification processes and products. This article presents the surface and interface behaviors of Gemini surfactants (12-2-12, (12)-2-(12), (14)-2-(14)). The results indicated that (12)-2-(12) could exhibit higher surface and interface active properties. The demulsification efficiency and related factors were also discussed. It showed that as an environmentally friendly and safer demulsifier, Gemini surfactant could exhibit better demulsification efficiency.

Methane Adsorption Characteristics of Lower Paleozoic Shale in China's Southern Sichuan and Northern Yunnan

The study into the methane adsorption properties of three formations of shale collected from the Lower Paleozoic strata in the research area indicates the following conditions: TOC content is an important factor in controlling the methane adsorption capacity of shale; the total content of clay minerals and the theoretical maximum methane adsorption capacity of shale have no significant correlation; when TOC content varies, control over methane adsorption capacity varies widely, revealing that the adsorption capacity of shale is affected by the amount and type of organic matter and may also be restricted by other macro conditions and microfactors.

The Study of Ultrasonic Technology in Flow-back Fracturing Fluid Treatment

Ultrasonic technology was, for the first time, utilized in the pretreatment of flow-back fracturing fluid (FBFF) in an oil field. The effects of each parameter, including frequency of ultrasonic, energy density, working time, and dosage of flocculant (poly-aluminum chloride), were investigated seriously in this study. Ultrasonic flocculation as a novel technology applied in FBFF provided good performance at reducing viscosity of fluid, even better than chemical oxidation.

An Advanced Method for the Preparation of Erucyl Dimethyl Amidopropyl Betaine and Acid Solution Properties

Abstract In this paper, an improved method for the preparation of erucyl dimethyl amidopropyl betaine (EDAB) was provided. The synthesis conditions were investigated. N,N-dimethyl-N′-erucyl-1,3-propylenediamine was synthesized by the reaction of erucic acid with N,N-dimethyl-1,3-propylenediamine at 170°C for 7 h, and then the intermediate was reacted with sodium chloroacetate in the mixture of methanol and water (3:7 v/v) at 60°C. The product was obtained after 6 h. The compounds were confirmed by IR and 1H-NMR. The properties of EDAB acid solution were also studied. The results indicated that viscosity of acid solution increased with decreasing hydrochloric acid concentration and was mainly controlled by surfactant concentration and temperature. The viscosity of an acid solution was maximum when the concentration of hydrochloric acid was at 15 wt%.

Molecular dynamic simulation of core–shell structure: study of the interaction between modified surface of nano-SiO2 and PAMAA in vacuum and aqueous solution

Abstract The interaction between acrylamide acrylicacid copolymer (PAMAA) and the modified surface of nano-SiO2 is investigated using the molecular dynamic (MD) simulation. The binding energies (Ebinding) of interface, the concentration profiles of PAMAA and functional groups (carboxyl and acylamino) of corresponding model, the mean square displacements (MSD) and diffusion coefficients (D) of PAMAA in four systems with different modifiers are all calculated at 325 K in vacuum. Vinyl trimethoxy silane (VTEOS) shows best modification effect in the systems mentioned above. Furthermore, the effects of temperature on the interaction between VTEOS modified surface of nano-SiO2 and PAMAA are studied at 300, 325, 350, 375 and 400 K in aqueous solution. Interesting results show that, water molecular layer reduces with the increase of temperature, and then improves the interaction between PAMAA and VTEOS modified surface of nano-SiO2. The corresponding Ebinding of interface, the radial distribution functions (RDF) of carbon atoms on the surface and oxygen atoms of water molecules, the concentration profiles of PAMAA on the surface of nano-SiO2, the MSD and D of PAMAA are all studied seriously to find the reason of this counterintuitive phenomenon.