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

Received: 14 April 2009 / Accepted: 10 March 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 η_o 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 η_o 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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*Corresponding author: email: ambar@ukm.my