β-Cyclodextrin modified cationic acrylamide polymers for flocculating waste drilling fluids

Treatment of drilling fluid waste during oil and gas drilling: a review

Oil and gas exploration and development provide important energy sources for the world, and drilling fluid is an essential engineering material for oil and gas exploration and development. During the drilling of oil wells, drilling fluids are eventually discarded as waste products after many cycles. Abandoned drilling fluid constitutes one of the largest wastes generated during oil and gas exploration and development. Drilling fluid contains many chemicals, which turn into pollutants during use. Furthermore, when drilling is carried out to reach reservoir, the drilling fluid becomes contaminated with crude oil. It may also mix with groundwater containing salts and heavy metals. The resulting pollutants and harmful substances threaten the environment, humans, animals, and plants. The variety and complexity of drilling fluid waste have increased in recent years. Various countries and regions are paying more attention to the ecological environment, and effective methods are urgently needed to solve problems associated with of environmental pollution caused by drilling fluid wastes. At present, various physical, chemical, and biological methods have been proposed for the treatment of drilling fluid wastes: safe landfilling, stabilization/solidification treatment, physicochemical treatment, thermal treatment, supercritical fluid treatment, bioremediation, etc. All of these methods show promising characteristics, and they each have advantages and limitations; thus, treatment methods need to be selected according to the actual application scenarios. This critical overview is based on an extensive literature review, and it summarizes and expounds on the current drilling fluid waste treatment technologies and proposes views future potential and outlook.

Synthesis and characterization of cyclodextrin-based acrylamide polymer flocculant for adsorbing water-soluble dyes in dye wastewater

A novel hydrophobic and cationic cyclodextrin-based acrylamide flocculant (AM-β-CD-DMDAAC) was prepared by chemical oxidative polymerization to adsorb water-soluble dyes in dye wastewater. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope and thermogravimetric (TG) measurements results demonstrated that the AM-β-CD-DMDAAC was successfully synthesized. The effects of pH, contact time, initial dye concentration, temperature and adsorbent dose on dye removal efficiency for AM-β-CD-DMDAAC flocculants were investigated. The kinetic data were found to follow the pseudo-second-order kinetic model. The equilibrium adsorption data were fitted to the Langmuir isotherm model, with the maximum adsorption capacity of 147.1 mg g-1. The adsorbent retained about 60% of the adsorption efficiency after three adsorption/desorption cycles, which implied a promising application as the dye adsorbent.

Preparation and Evaluation of a Profile Control Agent Base on Waste Drilling Fluid

The waste drilling fluid was treated by a flocculant and a pH regulator. And a novel profile control agent base on waste drilling fluid (PCAWDF) was prepared using polymer, formaldehyde, resorcinol, and thiourea as raw materials under mild conditions. PCAWDF was characterized by infrared (IR) spectroscopy and scanning electron microscope (SEM). Compared with the profile control agent prepared by the recirculated water (PCARW), PCAWDF exhibited comparable or better stability, salt resistance, and viscoelasticity. The results of parallel core plugging experiments showed that the profile improvement capability of PCAWDF was stronger than that of PCARW (for 3000 mg/L: 84.6% versus 83.1%; for 5000 mg/L: 91.8% versus 90.2%). The main performance indexes of PCAWDF could meet the need of profile control for the water injection wells. The method could solve the problem of waste drilling fluid treatment in an economic and environmental way.