Page 110 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

94 Gas Wettability of Reservoir Rock Surfaces with Porous Media

3.2 POLYMER GAS-WETTING ALTERATION AGENT
3.2.1 Fluorinated Acrylate Grafting Dopamine Copolymer
Fluoropolymer features lower surface energy as well as hydrophobic and oleo-
phobic properties, and dopamine (DA) features strong adhesion characteristics
with the surface of numerous substrates. Therefore, fluorinated monomer and
(DA were selected as the materials to research and develop fluorinated acrylate
grafting dopamine copolymer as a copolymer-based gas-wetting alteration
agent. The agent adheres itself strongly to the core surface of oil and gas reser-
voirs. The laboratory research results indicate that there is a remarkable gas-
wetting alteration effect.

3.2.1.1 PREPARING FLUORINATED ACRYLATE GRAFTING DOPAMINE
COPOLYMER:
1. Polymerization of fluorinated monomer and acrylic acid
50 mL N,N- dimethylformamide (DMF) was added to a 250 mL
three-necked flask and nitrogen was injected for 30 minutes. Then, half
of a mixture of Dodecafluoroheptyl methacrylate (F06), acrylic acid
(AA), and azodiisobutyronitrile were added into the three-necked flask
with a dropping funnel over 2 hours. After being heated for 2 hours at
80 C, the remaining mixture was added and was continued to be heated

for 2 hours. Then, another 0.5% monomer azodiisobutyronitrile was
added. After heating for 2 hours, the temperature of the reaction system
was dropped to 0 C.

2. Introducing dopamine to fluorinated acrylate polymer
After the above reaction system dropped to 0 C, carbon dimethyla-

mine hydrochloride (EDC-HCl) and dry dopamine hydrochloride
(Dopamine-HCl) were added to dehydrated solvent N,N- DMF, and stir-
red for 5 minutes after dissolution, and then added to the above reac-
tion system. Nitrogen was injected for 30 minutes, followed by
triethylanmine activation. The reaction was treated at room temperature
(25 C) for 24 hours. The resulting product was added to the diluted

hydrochloric acid, precipitated three times, and washed several times.
Finally, it was dried to obtain dopamine-containing fluoroacrylate
polymer.

3.2.1.2 PERFORMANCE EVALUATION OF FLUORINATED ACRYLATE
GRAFTING DOPAMINE COPOLYMER
3.2.1.2.1 Analysis of Infrared Spectroscopy
After the dopamine-containing fluoroacrylate polymer is precipitated and
dried, the column was coated with KBr pellet. After the polymer is spotted and
filmed, the infrared spectrogram is conducted. With a scanning range of
4000B400 cm 21 , the wave number was 0.01 cm 21 , and resolution ratio was
1cm 21 . The results of the infrared spectrogram with ungrafted dopamine
polymer are shown in Fig. 3.1.