Chemistry Preparation of SMA/CaCO3


by the Drilling Fluid Laboratory of China University of Geosciences. However, Ca-MMT (calcium bentonite, lamellar structure) could not reduce yield point because of its lamellar structure. Also, the content of SiO2 viscosity.


A


novel inorganic/organic hybrid, highly temperature-resistant fluid loss agent PSA/Ca-MMT/CaCl2 reported1


@SiO2 was not sufficient to remain Na2 SiO3 for appropriate


SMA (copolymer of styrene and maleic anhydride), which has diverse applications,2,3


can be modified easily due to the presence of anhydride


and aromatic functionalities. With granulated shape, CaCO3 is highly tem- perature-resistant and has lower resistance to movement than Ca-MMT.


Based on the above, an improved hybrid, high-temperature fluid loss agent with better rheological properties—SMA/CaCO3 sisting of SMA, SiO2, CaCl2


/CaCl2 , and CaCO3 Experimental


Synthesis and characterization of SMA/CaCO3 SMA was prepared by precipitation polymerization4


/CaCl2 @SiO2 : 0.7 g CaCO3 and 0.66


g KH550 were added to 20 mL ethanol in a flask equipped with a magnetic stirrer and reflux unit at 60 ºC for 3 hr; the solution was treated by ultra- sonic wave at 60 ºC for 3 hr. Afterward, modified CaCO3


was centrifuged,


and the precipitate was washed with ethanol three times to remove the excess KH550, which was absorbed on the CaCO3 CaCO3 was dried at 110 ºC for 24 hr in vacuum.5 CaCl2) of modified CaCO3


with silicon dioxide were prepared as PSA/Ca-MMT/CaCl2@SiO2.1 Next, SMA/CaCO3


/CaCl2 @SiO2 was attained. CaCO3 copolymer of modified CaCO3 and SMA, and SMA/CaCO3


, modified CaCO3 /CaCl2


surface. Finally, modified Graft polymer (containing


and SMA and encapsulation of graft polymer @SiO2


, graft were


characterized by FTIR spectra, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM).


Evaluation of SMA/CaCO3 /CaCl2 @SiO2


Drilling fluid property tests were performed according to the specifica- tions of the American Petroleum Institute.6


Formulation A = 3% bentonite + 0.75% sodium hydroxide + 100% H2O. Formulation B = Formulation A


+ 0.15% carboxymethylated cellulose (CMC) (by weight). AV and PV are associated with the viscosity of drilling fluid. YP is the yield value of the drilling fluid.


Results and discussion The FTIR spectra of the process product and SMA/CaCO3 shown in Figure 1. There were two absorption bands at 3672 cm−1


AMERICAN LABORATORY • 20 • SEPTEMBER 2014 Figure 1 – FTIR: CaCO3


/CaCl2 @SiO2 are and 1053 CaCO3 and SMA (c), and SMA/CaCO3


(a), modified CaCO3 /CaCl2


(b), graft polymer of modified @SiO2


(d). —was prepared. @SiO2 con- had previously been /CaCl2 cm−1


by Xiuhua Zheng, Shiwei Yang, and Zhongli Lei @SiO2 Loss Agent Based on PSA/Ca-MMT/CaCl2 The absorption band at 3029 cm−1 , 1453 cm−1


as a Fluid @SiO2


for modified CaCO3 of Figure 1b assigned to –NH2 bond, suggesting that CaCO3 was modified by KH550.7


the absorption bands of –CH2 were enhanced.8 centered at 623 cm−1


, and 3029 cm−1 and 1570 cm−1 and silicon oxygen of Figure 1c was assigned to –CH3 and


Meanwhile, the bands in Figure 1c were stretch-


ing vibrations peaks of polystyrene within SMA. The bands appearing at 1660 cm−1


bond. All of these indicated that hybrid polymers of modified CaCO3 SMA were synthesized. Two strong bands at 1104 cm−1


in Figure 1c were associated with peaks of amido and in


and 800 cm−1


Figure 1d corresponded to the Si–O–Si asymmetric vibration peak and silicon oxygen bond from the SiO2


; moreover, other peak intensity became


weak, which demonstrated that graft copolymer was encapsulated with silicon dioxide.


The TGA curves of graft polymer and SMA/CaCO3/CaCl2 @SiO2 are displayed


in Figure 2. From the curves of Figure 2a and b, the weight loss between 30 ºC and 200 ºC resulted from volatilization of water. The stage at 200–450 ºC was due to the loss of SMA, and at 450–750 ºC was ascribed to the disintegration of KH550. After 750 ºC, the remaining materials were CaCO3 (ash content: 20%) and CaCO3


/SiO2


(ash content: 50.93%), respectively,


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