Sains Malaysiana 39(5)(2010): 753–760
Viscoelastic Properties of Anionic
Brominated Surfactants
(Sifat
Viskokenyal Surfaktan Anionik Terbromida)
Larry Lee, Jumat Salimon & Mohd
Ambar Yarmo*
School of Chemical Sciences and Food
Technology
Universiti Kebangsaan Malaysia, 43600
Bangi, Selangor, Malaysia
Misni Misran
Department of Chemistry, University
of Malaya
50603 Kuala Lumpur, Malaysia
Diserahkan: 14 April 2009 / Diterima:
10 Mac 2010
ABSTRACT
The
scarcity of land based oil reserves has necessitated the exploration of off
shore oil. This exploration is often carried out in pristine waters and the use
of green chemicals is essential to reduce environmental degradation. In the
recovery of oil and gas from rocky formations, well bore fluids such as packer
fluids, fracturing fluids, conformance and permeability control fluids are
extensively employed. Potassium oleate as viscoelastic surfactants gives a low
partition coefficient when in contact with hydrocarbon. Bromination of the
oleate chain has been shown in this work to increase the partition coefficient
and still maintaining its viscoelasticity. The partition coefficient increased
to ca 8% compared to negligible for potassium oleate. A gel was formed when a
20% solution of potasssium 9-bromo stearate was mixed with 8% KCl. Contacting
this gel with hydrocarbon resulted in a loss of viscosity due to the improved
solubility of the brominated compound in hydrocarbon. This facilitates the
removal of the surfactants after its use as a fracturing fluid. The
viscoelastic properties were demonstrated using a Bohlin rheometer. The graph
of viscosity vs shear rate shows at first a shear rate independence up to a
shear rate of 0.2 s-1 and then falling with shear rate typical of a viscoelastic fluid.
The zero shear viscosity ηo varied from 18 Pa s to 220 Pa s whilst the shear viscosity at
100 s-1 ranged from
0.16 Pa s to 1.5 Pa s for surfactant concentration from 20% to 5%.
Keywords: Brominated
oleate; green chemistry; oil and gas; surfactants; viscoelastic
ABSTRAK
Kekurangan
simpanan takungan minyak mentah di daratan memerlukan carigali dilakukan di
bahagian lautan. Pencarian minyak mentah di lautan biasanya dilakukan
diperairan bersih dan penggunaan bahan kimia hijau adalah perlu bagi mengurangkan
kerosakkan alam sekitar. Bagi memperolehi minyak dan gas dari kawasan berbatu,
penggunaan bendalir pengerudi lubang seperti bendalir pemadat, bendalir
pemecah, pembentuk dan bendalir pengawal ketelapan digunakan. Kalium oleat
boleh digunakan sebagai surfaktan viskokenyal memberikan pemalar partisi yang
rendah bila bersentuhan dengan hidrokarbon. Dalam kajian ini rantai oleat
terbromida menunjukan peningkatan pemalar partisi disamping mengekalkan sifat
viskokenyalnya. Gel terbentuk apabila 20% larutan kalium 9-bromo sterat yang
dicampurkan dengan 8% KCl. Penyentuhan gel ini dengan hidrokarbon akan
menurunkan kelikatan yang disebabkan penambahbaikan kelarutan sebatian
terbromida dalam hidrokarbon. Ini akan menggalakkan penyingkiran surfaktan
bendalir pemecah selepas digunakan. Sifat viskokenyal ditunjukan dengan
mengunakan reometer Bohlin. Graf kelikatan terhadap kadar ricih menunjukan pada
permulaanya kadar ricih tidak bergantung kepada kadar ricihan pada 0.2 s-1 dan kemudian jatuh dengan kadar ricih yang biasanya sebagai
bendalir viscokenyal. Kelikatan ricih pada sifar ηo daripada 18 Pa ke 220 Pa dengan nilai kelikatan ricih pada julat
100s-1 daripada
0.16 Pa s ke 1.5 Pa s untuk kepekatan surfaktan antara 20 ke 5%.
Kata kunci:
kimia hijau; minyak dan gas surfaktan; oleat terbromida; viskokenyal
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*Pengarang untuk surat-menyurat: email: ambar@ukm.my
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