Abstract The dispersion performance of drilling fluids at high temperatures has always been a bottleneck in the research. To improve the dispersion of drilling fluid at high temperature and pressure, the natural Ca-based bentonite was modified with Na2CO3 and SDBS (sodium dodecyl benzene sulfonate: C12H25SO4Na) by microwave semi-dry method. The effects of the ratio of Na2CO3 to SDBS, radiation time, initial temperature and microwave power on the modification were investigated. In addition, the microstructure of the samples was obtained using infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the results showed that Na2CO3/SDBS was successfully inserted into the bentonite. In addition, the dispersion performance of the modified bentonite was evaluated in this paper, and the gelling value of the modified bentonite was 525 ml/15 g with an apparent viscosity of 22.5 mPa·s. The modified bentonite was compared with drilling-grade Na-based bentonite. The fluid loss (FLHTHP) of modified bentonite at high temperature and pressure is only 8 mL, the mud productivity is up to 25.71 m3/t, and the kinetic plastic ratio of modified bentonite is 1.5. The modified bentonite has better dispersion performance at high temperature and pressure.

ABSTRACT To reduce the shortcomings of existing filtering assistance, the talc was modified by a two-step method. In the first step, the talcum powder was heated by microwave in the acid solution. In the second step, the talcum powder was stirred with Hexadecyl Trimethyl Ammonium Bromide (HTAB) solution for optimum time under an optimum temperature. The optimum temperature, time and amount of HTAB were investigated by the batch membrane filtration experiments of kaolin suspension. The filtering effects of the new talc filter aid were evaluated with the filtration rate and moisture content in filter cake. The results showed that the optimum conditions were: the amount of 0.05 mmol/L HTAB was 100 ml, the modified temperature was 80℃ and the modified time was 60 min. When the filtrate was accumulated to 25 ml, the filtration time was 13.21 s shorter than others. The membrane flux of microfiltration was the largest (0.024 L/m2·s) when new talc filter aid was added into the kaolin suspension. The talc powder was characterized by Fourier Transform Infrared Spectroscopy and X-ray diffraction, which made the experimental results more obvious. Characterization results indicated that the hydrophobicity of the talc filter aid was excellent because microwave-assisted acidification talcum powder could absorb the cationic surfactants by electrostatic interactions. Finally, by comparing talc filtration assist with diatomite filtration assist, it is concluded that the filtration performance of talc filtration assist kaolin suspension is superior to other materials.

ABSTRACT Bentonite is the most important material used in oil and gas field drilling operations. However, the properties of natural bentonite cannot meet the requirements of bentonite for drilling. Therefore, researchers pay much attention to the modification of bentonite. The hydroxyethyl cellulose-acrylamide graft polymer was synthesized by microwave assisted, and the bentonite composite based on the graft polymer was prepared. FTIR, XRD and SEM results show that the polymer exists between the layers and the surface of the bentonite. Research on the bentonite composite showed that the yield point and filtration properties of bentonite composite are higher than natural bentonite at 90 to 150 celsius. The composite yield point / plastic viscosity ratio is more than 0.6 and the minimum fluid loss is only 9.3ml, which can meet the requirements of drilling-grade bentonite. This material has the potential to be a candidate for drilling applications.