Four alkyl propargyl bis(hydroxyethyl) ammonium surfactants with different lengths in hydrophobic tail (C8–C16) are prepared by direct alkylation of diethanolamine with alkyl bromides. The surfactants exhibit excellent surface properties. The critical micelle concentration (CMC) values of the surfactants
Acidizing is a widely established technique to increase hydrocarbon production from low-permeability reservoirs [
A variety of organic compounds can act as CIs during the acidization, including acetylenic alcohols, aromatic aldehydes, amines, nitrogen-containing heterocycles, and quinoline derivatives [
In this study, we developed a series of alkyl propargyl bis(hydroxyethyl) quaternary ammonium bromides with different hydrophobic lengths. By introducing propargyl group into quaternary ammonium surfactants, these compounds obtain a good corrosion inhibition ability and a good solubility in water/acid solution. Moreover, the compounds themselves are surface-active substances. When the carbon chain length of hydrophobic group is greater than 12, the solutions exhibit high viscosities and/or gel-like behavior at room temperature in the presence of sodium salicylate (NaSal); they still retain appreciable viscosities at a temperature above 90°C.
Distilled water was used as the solvent for all testing experiments. N-Alkyl bromide (Alfa Aesar, ≥99%, GC), diethanol amine (Alfa Aesar, ≥99%, GC), and propargyl bromide (Alfa Aesar, ≥99%, GC) were used without further purification. All other chemicals with analytical grade were purchased from Sinopharm Group Beijing Co., Ltd., China.
The viscoelastic surfactant solution for rheological test consists of 4.0 g surfactant
Surface tensions were measured at 20°C using a duNouy tensiometer. All surface tension measurements of the synthesized surfactants were conducted using distilled water as the solvent at mass concentration from 0.0001 wt.% to 1 wt.%. All the reported data points were average equilibrium values.
The apparent viscosity of surfactant was measured using a HAAKE MARS III Rheometer (Haake Technik Co., Germany) with the cylinder rotor DG41. In this study, the viscosity was reported under a temperature sweep range of 20 to 100°C at a steady shear rate of 170 s−1.
N80 steel specimen was immersed in 20 wt.% HCl solutions in the absence or presence of different concentrations of propargyl quaternary ammonium bromide for 4 h at 60 or 90°C, in which the ratio of volume (mL) of HCl solutions to surface area (cm2) of the specimens was 20 : 1. The specimens were taken out, washed with ethanol and acetone in turn, dried, and weighed accurately. Two specimens were used in each test, and the mean value of corrosion rate was calculated. The corrosion rate of each specimen was calculated as the equation below:
Four alkyl propargyl bis(hydroxyethyl) ammonium surfactants (Scheme
Synthesis of propargyl quaternary ammonium surfactants
The quaternary ammonium surfactants (
1H NMR spectrum of
1H NMR spectrum of
1H NMR spectrum of
1H NMR spectrum of
All surfactants
Surface tension at various surfactant concentrations of
Surfactants
Surface properties of three surfactants
Surfactants | CMC × 10−3 (mol L−1) |
|
|
|
|
---|---|---|---|---|---|
|
97.4 | 32.63 | 39.37 | 0.88 | 1.89 |
|
0.763 | 31.83 | 40.17 | 1.47 | 1.13 |
|
0.123 | 31.69 | 40.31 | 1.50 | 1.10 |
The corrosion rate (
Weight loss results for N80 steel in 20 wt.% HCl in the absence and presence of inhibitor for 4 h.
Entry | Surfactants |
|
|
|
|
IE% |
---|---|---|---|---|---|---|
(1) | 20% HCl | 90 | 0 | 593.8 | ||
(2) | 20% HCl | 60 | 0 | 281.3 | ||
(3) |
|
90 | 1.0 | 46.2 | 0.922 | 92.2 |
(4) |
|
90 | 1.0 | 10.4 | 0.982 | 98.2 |
(5) |
|
60 | 1.0 | 3.75 | 0.982 | 98.2 |
(6) |
|
90 | 1.0 | 17.2 | 0.971 | 97.1 |
(7) |
|
90 | 0.39 | 12.8 | 0.979 | 97.9 |
(8) |
|
90 | 0.10 | 32.4 | 0.945 | 94.5 |
(9) |
|
90 | 0.039 | 59.8 | 0.899 | 89.9 |
(10) |
|
90 | 0.010 | 517.4 | 0.129 | 12.9 |
(11) |
|
90 | 1.0 | 20.7 | 0.965 | 96.5 |
(12) |
|
90 | 1.0 | 163.4 | 0.725 | 72.5 |
As shown in Table
Figure
The apparent viscosity of 4 wt.% of surfactant
The viscoelastic surfactants own good viscosity and elasticity and thus can be used in fracturing for suspending sands. The fluid composes small molecules and has no residue left in reservoirs after fracturing. Hence, the conductivity is very high with no formation damage [
Four alkyl propargyl bis(hydroxyethyl) ammonium surfactants with different lengths in hydrophobic tail were high yield synthesized by following an efficient method from commercially available chemicals. Structures of the synthesized surfactants were characterized by 1H NMR. Surface tension, corrosion inhibition efficiency, and apparent viscosity were evaluated. The results indicate these surfactants exhibit excellent surface properties. The critical micelle concentration (CMC) values of the surfactants
The authors declare no financial conflicts of interest.
This research was financially supported by PetroChina Innovation Foundation (Grant no. 2016D-5007-0205) and the Science Foundation of China University of Petroleum, Beijing (Grant no. 2462015YJRC027).