Research Article | | Peer-Reviewed

Test on Bitter Leaf Sap as a Surfactant for Wettability Alterations in Enhanced Oil Recovery from Sand Aggregates

Received: 23 March 2025     Accepted: 10 April 2025     Published: 20 June 2025
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Abstract

Alteration of reservoir-wettability is very important during Enhanced Oil Recovery (EOR) process since it helps to mobilize hydrocarbon and thus increase its recovery from the reservoirs. However, conventional wettability alteration agents used in the industry are inorganic chemicals which are expensive, constitute and have been found to be harmful to the environment. Hence, there was need for cheaper and environmentally-friendly alternative. Also, there was need to find more use for abundant local materials which have are under-utilized. In this article, bitter leaf sap (BLS) was studied to ascertain its possibilities as bio-surfactant for wettability alteration. In order to establish its phytochemical composition, BLS was analyzed using SEM, FT-IR, XRD, and XRF in accordance with ASTM standards. Wettability alteration capacity of three different concentrations of BLS solution on three sand aggregates was investigated. Active compounds which qualified BLS as bio-surfactant were identified from phytochemical analyses. Phytochemical analyses of BLS do not reveal any compounds that could be dangerous to the environment. The results from wettability tests obtained showed that core Sample A, (grain-size 0.118 cm) gave highest degree of wettability alteration with wettability index change from - 0.3030 to - 0.2020. Degree of wettability alteration increased as grain size of sand increased. It was also found that the degree of wettability alteration increased as concentration of BLS increased. Although, BLS could cause wettability alteration, its degree of alteration was lower than the degree of alteration of industrial wettability alteration agent.

Published in American Journal of Chemical Engineering (Volume 13, Issue 3)
DOI 10.11648/j.ajche.20251303.11
Page(s) 53-65
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Wettability Alteration, Amott Test, Bitter Leaf Sap, Sand Aggregates, Enhanced Oil Recovery

1. Introduction
Wettability of porous medium depends on the surface roughness, the pore size, layer of the adsorbed liquid and the adsorptive properties of minerals . The distribution and the flow of fluids in the reservoir are strongly affected by the wettability of the reservoir. The wettability of reservoir rocks contributes to effectiveness of enhanced oil recovery. During enhanced oil recovery process, dispersed oil droplets coalesce, create a zone saturated with oil then migrate to the production well . Hydrophilic rocks allow easy migration of oil for production. For this purpose, different methods are used in modifying wettability in favour of hydrophilic condition - chemical and thermal . Wettability alteration enables change of the reservoir from hydrophobic to hydrophilic condition. Wettability alteration agents used in the industry are inorganic chemicals that can either produce higher pore-scale displacement efficiency or increase the sweep efficiency in the reservoir . These conventional chemicals have been found to damage reservoirs, pollute groundwater resources, and destroy the ecological environment of reservoirs. They are synthetic substances and not easy to biodegrade . The ability of a bio-based surfactant to alter wettability has been tested. In this study, sap from bitter leaf shrub (Vernonia amygdalina) was tested as a bio-based surfactant for its potential to alter the wettability of sand aggregates. Biologically active compounds of Vernonia amygdalina are saponins, alkaloids, terpenes, steroids, coumarins, flavonoids, phenolic acids, lignans, xanthones and anthraquinones . Bitter leaf contains, along other nutrients, phosphorus, ascorbic acid, iron, -carotene, calcium, water, and fibre, essential oils, iso-acids, and a-acids found in it . People in Nigeria's South-Southern and South-Eastern Region consume the most of it. .
Bitter leaf (Vernonia amygdalina) has been used medicinally as antioxidant ; treatment for malaria. treatment for parasitic infestations ; many other uses . In spite of the many benefits of bitter leaf sap only very small quantity is used to meet these benefits. The quantity utilized is very minimal compared with the quantity wasted. The phytochemistry analysis in literature shows that Bitter leaf is made up of the following key chemical compounds: Flavonoids, Deoxy andrographolide, 14-deoxy-n, andrographolide 12-didehydroandrographolide, Homandrographolide, Ketones, Alkane, Aldehydes, Potassium, Sodium, Calcium, Acid grit and Resin . All these chemical components of bitter leaf sap suggest the possibility of altering wettability. Bitter leaf sap is biodegradable, like some plants used as substitute for inorganic chemicals in oil industry .
2. Materials and Methods
2.1. Materials and Preparation
The materials used in this study are bitter leaf, crude oil, conventional chemicals for wettability alteration and sharp sand. The bitter leaf was obtained from Oleh, crude oil sample was obtained from a field in the Niger Delta area of Nigeria. The sharp sand was obtained at Delta State University, Oleh Campus. Bitter leaf sap (BLS) was crushed into a fine paste using a mortar and pestle. The ground bitter leaf paste was pressed to recover the sap. The sharp sand was washed under running water for 30 minutes to remove all debris. Then, the sharp sand was sun-dried for 21 days until constant moisture content. Then filtered to remove big particles and sieved into various grain sizes (0.025cm3, 0.06cm3 and 0.118cm3).
2.2. Phytochemical Analysis on Bitter Leaf Sap, Analysis on Sand Samples and Analyses on Crude Oil
The bitter leaf was subjected to phytochemical analysis using UV-Visspectrophotometry (Shimadzu UV-1800). FTIR analysis (PerkinElmer Spectrum 2) was used to recognize functional groups in the bitter leaf. XRD analysis (Bruker D8 Advance) and XRF (PANalytical Epsilon 3) were used to determine mineral composition and elemental contents of sharp sand respectively. Crude oil properties were measured using a Brookfield DV-II+ Pro viscometer, and sulfur content was determined using ASTM D4294. The contents were determined in agreement with the process described in literature: tannin amino acids ; carbohydrate content and phenolic .
2.3. Experimental Procedure
Three sand aggregates were tested with three different concentrations of bitter leaf sap solution. Eight core samples were prepared from each of the sand aggregate. One of such core samples was prepared to be water-wet. The other seven of such core samples were prepared to be oil-wet. Bitter leaf sap was prepared to be 100%, 50% and 25% concentrations. The wettability index of the water-wet core sample of each of the sand aggregate was determined. The wettability index of one of the oil-wet sample from each of the sand aggregate was also determined. In order to alter their wettability, three of the oil-wet samples were treated with 100%, 50% and 25% concentrations of bitter leaf sap respectively. Subsequently, the wettability indexes of the three samples treated with BLS were determined. The wettability alterations of the samples were ascertained by the results. The remaining three of the oil-wet samples were treated with 70% concentrations of three different conventional wettability alteration agents respectively. Subsequently, the wettability indexes of the three samples treated with BLS were determined. Also, the wettability indexes of the three samples treated with conventional wettability alteration agents were determined. The wettability tests were determined by Amott test and Amott-Harvey Criterion was used to determine the wettability indexes.
The process for testing wettability of each core samples began at the residual oil saturation. Each core sample to be tested was initially saturated with water and crude oil. The fluids in each core sample tested are reduced to Sor (residual oil saturation) by forced displacement of the oil. The core sample was immersed in crude oil for 20 hours, and the amount of water displaced by the spontaneous imbibition of oil was measured. The water was displaced to the residual water saturation (Siw) by oil, and the total amount of water displaced (by the imbibition of oil and by forced displacement) was measured. Also, the core sample was immersed in brine for 20 hours, and the volume of oil displaced by spontaneous imbibition of water was measured. The oil remaining in the core was displaced by water to Sor and the total amount of oil displaced (by the imbibition of water and by forced displacement) was measured. The Amott-Harvy index for water and oil was determined from the following formulas.
Io=Sos1-Swi-Sor(1)
Iw=Sus1-Swi-Sor(2)
WIAmott-Harvey=Iw-Io(3)
Where:
WIAmott-Harvey is Amott-Harvey wettability index,
Io is the displacement-by-oil ratio
Iw is the displacement-by-water ratio
Sos is the volume of water displaced by the spontaneous imbibition of oil
Sus is the volume of oil displaced by the spontaneous imbibition of water
Swi is the irreducible water saturation
Sor is the residual oil saturation
According to studies of wettability index, the rock is hydrophilic when Iw= ≤ 0.3 ≤ 1.0; neutral rock wettability, respectively (−0.3 ≤ Iw= ≤ 0.3) and hydrophobic rock, where −1 ≤ Iw= ≤ −0.3 . Amott-Harvey wettability criterion is as shown in Table 1.
Table 1. Wettability criterion based on Amott-Harvey index.

Wettability

WI(Amott-Harvey)

Water Wet

0.3 to 1

Intermediate

-0.3 to 0.3

Oil wet

-1 to-0.3

3. Results and Discussion
3.1. Qualitative and Quantitative Analysis of Samples
The results obtained from the qualitative phytochemicals analysis of bitter leaf sap (this study) are presented in Table 2. Results from other articles were presented alongside for easy comparison . As shown in the Table 2, the Steroids, phenols, xanthoproteic compounds, and flavonoids were consistently detected. while Carbohydrates were consistently present also. Terpenoids showed variability, being absent in some reports , suggesting potential geographic or methodological differences. While Phytosteroids were detected in other studies but absent in this study. Stain (Fix fat and oil) and Phlobatannins were not always present, they are not major components. These findings emphasize that environmental conditions, extraction methods, and preparation techniques influence the phytochemical detected in the results.
Table 2. Qualitative Phytochemicals Analysis for Bitter leaf sap.

Parameters

This study

References

Ruth et al. (2021)

Ojeaga et al. (2021)

Ogunlade et al. (2022)

Terpenoid

+

+

-

+

Alkaloid

+

++

+

+

Phlobatannins

-

-

+

+

Steroid

+

+

+

+

Saponin

+

++

+

+

Phyto-steroid

-

+

+

+

Phenol

+

+

+

+

Triterpenoid

++

++

+

+

Fehling’s (Flavonoids)

+

+

+

+

Xanthoproteic

+

+

+

+

Keller Killanis (Glycoside)

++

+

+

+

Alkaline Reagent

++

+

+

+

Iodine (Carbohydrates )

+

+

+

+

Benedict’s (Carbohydrate )

+

+

+

+

Stain (Fix fat and oil)

-

+

-

+

Gelatine (Tannin)

-

+

+

+

KEY = ++ abundantly present, + present, - absent
Table 3. Quantitative Phytochemicals Analysis for Bitter leaf sap.

Parameters

This study

References

Ruth et al.(2021)

Ojeaga et al. (2021)

Tannim(mg/tannin)

0.4633

12.33±0.01

-

Phenolic Content (mEq/GAE)

11.235

44.763±0.02

-

Flavonoid(mEq/QE)

7.706

-

18.00±0.02

Reducing Power (mg/glucose)

14.589

3.43±0.01

-

Total Carbohydrate (mg/glucose)

10.899

-

10.00±0.02

Saponin

5.823

-

6.00±0.05

Total alkaloids

8.305

5.6±0.01

-

Lipids

3.230

-

2.72

Steroids

0.42

0.30±0.01

-

Proteins (mg/100g)

9.563

-

5.20±0.02

Results from quantitative phytochemical analysis of the bitter leaves sap (this study) are presented in Table 3. Results from other articles were presented alongside for easy comparison . Tannin content was 0.4633 mg/tannin in this study but higher values (12.33±0.01) were reported by Ruth et al. (2021). Flavonoids concentrated was 7.706 mEq/QE but Ojeaga et al. (2021) recorded 18.00±0.02 mEq/QE. Phenolics was 11.235 mEq/GAE) while Ojeaga et al. (2021) reported 44.76±0.02 mEq/GAE. Carbohydrates have a greater concentration in this study (10.899 mg/glucose) compared to 10.00±0.02 mg/glucose reported by Ojeaga et al. (2021). Alkaloids are higher (8.305) compared to 5.6±0.01 reported by Ruth et al. (2021). Saponins are less abundant in this study (5.823) but higher (6.00±0.05) report of Ojeaga et al. (2021). Lipids are slightly higher in this study (3.230) than report of Ojeaga et al. (2021) recorded as 2.72. Proteins are higher in this study (9.563 mg/100 g) than in report of Ojeaga et al. (2021) which recorded 5.20±0.02. Steroids recorded in this study was 0.420 but 0.30±0.01 was recorded by Ruth et al. (2021).
3.2. The Fourier-Transform-Infrared Spectroscopy (FT-IR) Analysis of Dry Bitter Leaf
The Fourier-Transform-Infrared Spectroscopy (FT-IR) of dry bitter leaf is shown in Figure 1.
Figure 1. FT-IR analysis of dry bitter leaf.
Several functional groups that can influence wettability alteration were observed in the FT-IR analysis of dry bitter leaf. Wettability alteration influence better oil recovery . The functional groups recognized (hydroxyl, carbonyl, ether/ester) encourage alteration from oil-wetness to water-wetness and improve oil displacement efficiency. Carbonyl compounds such as ketones and aldehydes with C=O stretching (1739.5 cm⁻¹) was observed. Carbonyl compounds enhance surface polarity thus support water-wet conditions. C=C stretching (1648.0 cm⁻¹) is linked with alkenes or aromatic compounds, though they are non-polar, they can effect wettability alteration . C-H bending (1452.0 cm⁻¹, 1373.8 cm⁻¹) indicating alkanes and methyl groups was found. C-O stretching (1247.5 cm⁻¹, 1095.8-1013.8 cm⁻¹) indicates alcohols, ethers, or esters. These groups have the capacity to increase hydrophilicity and expedite water-wetness . C-H stretching (2918.5 cm⁻¹, 2847.7 cm⁻¹) indicates aliphatic hydrocarbons. O-H stretching (3257.7 cm⁻¹) indicates alcohols, phenols, or carboxylic acids, which aid hydrophilicity . C≡C stretching (2105.9 cm⁻¹, 1919.6 cm⁻¹) indicate alkynes or combination bands.
3.3. X-Ray Diffraction (XRD) Analysis of Bitter Leaf
The X-ray diffraction analysis spectrum for bitter leaf is shown in Figure 2, reveals intensity peaks at different angles (2θ), each conforming to different crystalline phases in the sample. The identified phases include Periclase (MgO) which enhances water-wetness in reservoirs, improving fluid injection efficiency and boosting oil recovery . Zinc Aluminium Phosphate and Sulfates - Hanksite (Na K(SO ) (CO )2Cl), Minoruzaite, Woodhouseite (CaAl (PO )(SO )(OH) transform the surface chemistry of reservoir rocks, encouraging water-wet conditions that facilitate improved oil displacement . Haggstattite (syn) and Hicksite are also present, contributing to the overall mineral profile of bitter leaf. The presence of these minerals indicates the potential for wettability alteration, shifting the reservoir surface from oil-wet to water-wet, which is critical for improving the efficiency of enhanced oil recovery (EOR) processes. Zinc Aluminium Phosphate, is hydrophilic and can increase water-wettness. Sodium and potassium salt present in Hanksite may influence ion exchange processes that affect wettability . Hydroxyl groups in Woodhouseite can interact with water, encouraging water-wetness.
Figure 2. X-ray diffraction analysis spectrum for Bitter leaf.
The phase data view from X-ray diffraction (XRD) analysis on dry bitter leaves is shown in Figure 3. Phases identified are Flagstaffite, syn (Blue colour), Periclase (Aqua), Zinc Aluminium Phosphate (Black), Woodhouseite (Green), Hanksite (Red), Minguzzite (Cyan). The colour-coded markers at the bottom show the peak positions for each identified phase, which correspond to the peaks in the red diffraction pattern. These minerals possess distinct chemical and structural properties that can influence the wettability of reservoir rocks. Hanksite and Woodhouseite contains sulphur salts which influences ion exchange processes, thus affecting wettability . Woodhouseite containing hydroxyl groups, could interact preferentially with water, promoting water-wetness.
Figure 3. Phase Data view from X-ray diffraction (XRD) analysis on dry Bitter leaf.
3.4. X-Ray Fluorescence (XRF) Analysis of Sharp Sand
The X-ray fluorescence (XRF) analysis on sharp sand is shown in Table 4. As shown in the table, Silicon dioxide (SiO2) is the major constituent (95.2%) of the sand as such Quartz is the mineral. Aluminium Oxide (Al2O3) makes up 1.9% of the sand. Iron (III) Oxide (Fe2O) makes up 0.5% of the sand. The composition of Calcium Oxide (CaO) is 1.2%. The composition of Magnesium Oxide (MgO) is 0.1%. The composition of Potassium Oxide (K2O) is 0.3%. The content of Silt is 0.2%. The content of organic impurities is 0.5%.
Table 4. X-ray Fluorescence Analysis on the Sharp Sand.

Compound

SiO2

Al2O3

Fe2O3

CaO

MgO

K2O

Silt Content

Moisture Content

Organic Impurities

Composition, %

95.2

1.9

0.5

1.2

0.1

0.3

0.2

0.15

0.5

3.5. Petroleum Crude Oil Analysis
The result from analysis of petroleum crude oil is presented in Table 5. The table shows that the Sulphur content was 0.5%, classifying the crude as sweet . The specific gravity is 0.95 confirms the heavy nature of this crude oil. The asphaltene content is 0.9% The carbon residue, at 8.0%, is high and indicates that crude oil has a significant number of heavy components. The viscosity of the crude oil was 72.0 Pa.s, which is relatively high, indicating that the oil is quite thick and resistant to flow, typical of heavy crudes. The crude oil is heavy crude (API gravity of 17.8). This classification is further supported by its density of 0.95g/cm³.
Table 5. Data obtained from Petroleum Crude Oil Analysis.

Parameters

API Gravity

Specific Gravity

Density

Sulphur Content

Viscosity

Asphaltene Content

Carbon Residue

Composition

17.80

0.95

0.9g/cm3

0.6%

72.0pa.s

0.9%

8.0%

3.6. Results of Wettability Experiment
In Table 6, results from wettability test of the different core samples were presented. The grain size of Sample A is 0.118cm3, Sample B has grain size of 0.06cm3, while the grain size of Sample C is 0.025cm3. As shown in Table 6, wettability indices of the water-wet samples of grain size 0.118cm3, Aw and oil-wet samples of grain size 0.118cm3, Ao, are 0.3030 and -0.30303 respectively. These indices agree with the criteria shown in Table 1. The wettability index of the oil-wet samples A, treated with 100% BLS, Xo100, was -0.2020. A significant difference between wettability indices of Ao and Ao100 was therefore obtained. as presented in Table 6, wettability index of Ao100 is within the range of intermediate-wetness, indicating that treatment with 100% BLS has brought about a significant alteration of wettability. The wettability index of the oil-wet Sample A, treated with 50% BLS, Ao50, was -0.2222, thus, showing a significant difference between wettability indices of Ao and Ao50. Wettability index of Ao50 is within the range of intermediate-wetness, indicating that treatment with 50% BLS has caused a substantial change in wettability. It was also observed that there was marked difference between wettability indices Ao50 and Ao100 which suggests that concentration of BLS affect degree of wettability alteration. The wettability index of the oil-wet Sample A, treated with 25% PSS, Ao25, was shown to be -0.2424. As observed, there was notable difference between wettability indices of Ao and Ao25. Wettability index of Ao25 was within the range of intermediate-wetness, indicating that treatment with 25% BLS has caused a significant alteration of wettability. Also, there was comparable difference between wettability indices Ao25, Ao50 and Ao100 suggesting that concentration of BLS has effect on degree of wettability alteration. As concentration of BLS increased, the wettability index tends more towards water-wetness. BLS of 100% concentration produced the highest degree of wettability alteration. In addition, it was observed that 100% concentration of BLS could not fully convert oil-wet sample to become water-wet. There was noticeable difference between Aw and Ao100. However, since BLS has the capacity to alter wettability, it can improve microscopic efficiency of EOR process. The increase in the microscopic sweep recovery corresponds with increase in the recovery factor .
Table 6. Experimental Data obtained with Core Samples for Wettability Alteration.

Core Samples

Sand Grain Size (cm)

Wettability Before Test

Concentration of PSS Tested with (%)

Comments

Symbol

Wettability Index

Wettability After Test

A

0.118

Water-wet

No test

Control sample

Aw

0.3030

Water-wet

Oil-wet

No test

Control sample

AO

-0.3030

Oil-wet

Oil-wet

25

Test sample

AO25

-0.2424

Intermediate

Oil-wet

50

Test sample

AO50

-0.2222

Intermediate

Oil-wet

100

Test sample

AO100

-0.2020

Intermediate

B

0.06

Water-wet

No test

Control sample

Bw

0.3131

Water-wet

Oil-wet

No test

Control sample

BO

-0.3132

Oil-wet

Oil-wet

25

Test sample

BO25

-0.2727

Intermediate

Oil-wet

50

Test sample

BO50

-0.2525

Intermediate

Oil-wet

100

Test sample

BO100

-0.2323

Intermediate

C

0.025

Water-wet

No test

Control sample

Cw

0.3333

Water-wet

Oil-wet

No test

Control sample

CO

-0.3030

Oil-wet

Oil-wet

25

Test sample

CO25

-0.2929

Intermediate

Oil-wet

50

Test sample

CO50

-0.2727

Intermediate

Oil-wet

100

Test sample

CO100

-0.2525

Intermediate

As shown in Table 6, wettability index of the water-wet samples of grain size 0.06cm3, Bw, and index of the oil-wet samples of grain size 0.06cm3, Bo, were shown to be 0.313131 and 0.31313 respectively. The wettability index of the oil-wet samples of grain size 0.06cm3, treated with 100% , Bo100, was -0.2323 Wettability index of Bo100 was within the range of intermediate-wetness, demonstrating that treatment with 100% BLS has brought about a change in wettability. Significant difference was observed between wettability indices of Bo and Bo100. The wettability index of the oil-wet samples of grain size 0.06cm3, treated with 50% BLS, Bo50, was -0.2525. Wettability index of Bo50 was within the range of intermediate-wetness, showing that treatment with 50% concentration of BLS has brought about a significant adjustment of wettability. There was obvious difference between wettability indices of Bo and Bo50. Also, observed, there was obvious difference between wettability indices Bo50 and Bo100 suggesting that concentration of BLS has effect on degree of wettability alteration. The wettability index of the oil-wet samples of grain size 0.06cm3, treated with 25% BLS, Yo25, was shown to be -0.2727 (intermediate-wetness). Observable difference between wettability indices of Bo and Bo25 was noticed. Comparative differences between wettability indices Bo25, Bo50 and Bo100 were observed, signifying that concentration of has effect on degree of wettability alteration. As concentration of BLS increased, the wettability index tends more towards water-wetness with 100% concentration of BLS producing the highest degree of wettability alteration. However, it was observed that there was noticeable difference between Bw and Bo100 because 100% could not fully convert sample to water-wet. The tests conducted also indicated that higher oil production can be obtained by treating reservoir with BLS. These trends observed conform with results in existing literature .
As shown in Table 6, wettability indices of the water-wet samples of grain size 0.025cm3, Cw, and the oil-wet samples of grain size 0.025cm3, Co, was was shown to be 0.3333 and -0.3030 respectively. These values were in agreement with the criteria shown in Table 1. The wettability index of the oil-wet Sample C, treated with 100% BLS, Co100, was shown to be -0.2525 (intermediate-wetness) indicating significant alteration of wettability by treatment with 100% concentration of BLS. As observed, there was marked difference between wettability indices of Co and Co100. The wettability index of the oil-wet samples of grain size 0.025cm3, treated with 50% BLS, Co50, was shown to be -0.2727(intermediate-wetness). It showed that significant alteration of wettability by treatment with 50% concentration of BLS. The wettability index of the oil-wet samples of grain size 0.025cm3, treated with 25% BLS, Co25, was shown to be -0.2929 (intermediate -wetness), indicating that treatment with 25% BLS has brought about a significant alteration of wettability. Also, observed, there was marked difference between wettability indices Co25, Co50 and Co100 suggesting that concentration of BLS has effect on degree of wettability change. As concentration of BLS increased, the wettability index tends more towards water-wetness. 100% BLS produced the highest degree of alteration. From earlier study it has been shown that oil production increased as the wettability changed in the direction of the water-wetness .
3.7. Comparison of Wettability Indices of Specified Aggregates of Sand Samples
As shown in Figure 4, there is marked difference between wettability indices of Aw, Aw and Aw. it shows that grain size of core has effect on wettability of sand sample. It could be observed that as grain size increased, the wettability index tend towards oil-wetness. Similar trend was observed between Ao, Bo and Bo in one hand; Ao100, Bo100 and Co100 in another. The trend also extended to Ao50, Bo50 and Co50 then Ao25, Bo25 and Co25.
Figure 4. Comparison of Wettability Indices of Samples in Relation to Specified Grain Sizes of Samples.
Figure 5. Comparison of Wettability Indices of in Relation to Specified Sand Samples Concentrations of BLS.
As shown in Figure 5, there is marked difference between wettability indices of Aw, Ao, Ao100, Ao50 and Co25. Especially, after treating samples with BLS. It was shown that as concentration of BLS increase, the degree of wettability alteration, sample tends ttowards water-wetness. Highest degree of alteration was observed with 100% concentration of BLS. The trend also extended to Bw, Bo, Bo100, Bo50 and Bo25. and Cw, Co, Co100, Co50 and Co25.
3.8. Comparison of Some Industrial Based Wettability Alteration Chemical Agent with Plantain Stem Sap.
Comparison between selected conventional wettability alteration chemicals and bitter leaf sap were made. The selected wettability alteration chemical agents are:
1. Petroleum sulfonates + alkyl ether sulphate (PSAES)
2. 1.25wt% Na2CO3 as alkali + 0.1wt% Petro step B-100 as surfactant (SCPSB)
The Results of wettability indices of sand samples treated with the specified wettability alteration agents are presented in Table 7.
Table 7. Comparison between Conventional Wettability Alteration Chemical Agent with BLS.

Core Samples

Sand Grain Size (cm)

Test Agent

Concentration of Agent Tested with (%)

Comments

Symbol

Wettability Index

Wettability After Test

A

0.118

PSAES

70

Test sample

APSAES

0.4444

Water-wet

SCPSB

70

Test sample

ASCPSB

0.4444

Water-wet

No test

No test

Control sample

AO

-0.3030

Oil-wet

BLS

100

Test sample

AO100

-0.2020

Intermediate

B

0.06

PSAES

70

Test sample

BPOA

0.4343

Water-wet

SCPSB

70

Test sample

BSCP

0.4242

Water-wet

No test

No test

Control sample

BO

-0.3131

Oil-wet

BLS

100

Test sample

BO100

-0.2323

Intermediate

C

0.025

PSAES

70

Test sample

CPOA

0.3939

Water-wet

SCPSB

70

Test sample

CSCP

0.3939

Water-wet

No test

No test

Control sample

CO

-0.3030

Oil-wet

BLS

100

Test sample

CO100

-0.2525

Intermediate

As shown in Table 7, Oil-wet Sample A treated with 70% concentration PSAES had wettability index of 0.4444 (water-wetness). Similarly oil-wet Sample A treated with 70% concentration SCPSB had wettability index of 0.4444 (water-wetness). Conversely, oil-wet Sample A treated with 100% concentration of bitter leaf sap had wettability index of -0.2020 (intermediate-wetness). Likewise, for Sample B, when 70% concentration of PSAES was used for wettability alteration, the wettability index of the sample change to 0.4343 (water-wetness), but with 100%, concentration bitter leaf sap changed wettability index of sample to -0.2323 (intermediate-wetness). Also, 70% concentration of SCPSB produced wettability index of 0.4242 (water-wetness). For oil-wet Sample C, when 70% concentration of PSAES was used wettability index changed to 0.3939 (water-wetness), but 100%, concentration of bitter leaf sap had -0.2525 (intermediate-wetness). However, 70% concentration of SCPSB produced wettability index of 0.3939 (water-wetness). Results show that BLS has the capacity to alter wettability of sand samples as shown in by other plant in literature . However, it is not as effective as some of the industrial-based agent in altering wettability. Wettability alteration capacity is useful in enhancing oil recovery from reservoir.
4. Conclusion
Phytochemical analyses of bitter leaf sap have shown that BLS is non-toxic to the environment. Results from phytochemical analyses of BLS consistently suggest that BLS has potential wettability alteration compounds. In addition, since BLS is organic matter, it is bio-degradable. It has economic advantage because it is easily availability and affordability. The results of this study showed that regardless of size of sand grain, the wettability alteration was higher as concentration of bitter leaf sap increased. Core sample of smaller grain had comparatively lower degree of wettability alteration. Wettability indices of intermediate-wetness were achieved by BLS which was considerably lower in comparison to selected conventional wettability alteration chemicals. The wettability indices observed at various concentrations of BLS confirm that bitter leaf sap could effectively alter the wettability of reservoir, successfully mobilize entrapped oil and hence enhance oil recovery. Although, it was observed from this study that dilution reduces the effectiveness of BLS, nevertheless 25% concentration of BLS revealed significant result. Thus BLS portrays oil-recovery potential and comparative result to conventional chemical agents. This research also demonstrated that BLS does not contain toxic components thus could be used as a wettability alterations agent without threat to environmental health.
Abbreviations

BLS

Bitter Leaf Sap

EOR

Enhanced Oil Recovery

WI

Wettability Index

FT-IR

Fourier-Transform-Infrared Spectroscopy

XRD

X-Ray Diffraction

XRF

X-ray Fluorescence

PSAES

Petroleum Sulfonates + Alkyl Ether Sulphate

SCPSB

1.25wt% Na2CO3 as Alkali + 0.1wt% Petro Step B-100 as Surfactant

Author Contributions
Michael Chukwunweike Ogbue: Conceptualization, Data curation, Formal Analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Writing – original draft, Writing – review & editing
Johnbull Okperhie: Data curation, Formal Analysis, Funding acquisition, Methodology, Resources, Validation
Ezizanami Stephen Adewole: Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation
Kelani Olafinhan Bello: Conceptualization, Formal Analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation
Conflicts of Interest
The authors declare that there is no conflict of interest.
References
[1] Falode O., Manuel E. (2014): Wettability Effects on Capillary Pressure, Relative Permeability, and Irreducible Saturation Using Porous Plate. Journal of Petroleum Engineering, Pp. 1-12.
[2] Rychlicki S., Stopa J., Uliasz-Misiak B., Zawisza L. (2003): Kryteria typowania złóż do zasto- sowania zaawansowanej metody wydobycia ropy naftowej poprzez zatłaczanie CO. Gospodarka Surowcami Mineralnymi, vol. 27, no. Pp. 125-139.
[3] Donaldson E. C., Civan F., Ul Alam M. W. (1988): Relative Permeabilities at Simulated Reservoir Conditions. Society of Petroleum Engineers Reservoir Engineering, vol. 3, no. 4, Pp. 1323-1327.
[4] Wang Y., Xu H., Yu W., Bai B., Song X., Zhang J. (2011): Surfactant induced reservoir wettability alteration: Recent theoretical and experimental advances in enhanced oil recovery. Petroleum Science, vol. 8, issue 4. Pp. 463-476.
[5] Wang, J., Gu, F., Han, W., Fu, L., Dong, S., Zhang, Z., Ren, Z., & Liao, K. (2023a). Green surfactant made from cashew phenol for enhanced oil recovery. ACS Omega.
[6] Wang, Y., Gao, Y., & Li, X. (2023b). Molecular interaction mechanisms between functional groups and reservoir rocks: Implications for wettability alteration in EOR. Fuel, 327, 125020.
[7] Smith, R., Allen, T., & Decker, L. (2019). Wettability alteration with bio-surfactants from Quillajasaponaria for enhanced oil recovery. Journal of Industrial and Engineering Chemistry, 76, 174-181.
[8] Saxena N, Pal N, Dey S, Mandal A. (2017) Characterizations of surfactant synthesized from palm oil and its application in enhanced oil recovery. Journal of the Taiwan Institute of Chemical Engineers.; 81: 343-355
[9] Khorram, M., Shojaosadati, S. A., Khalilzadeh, R., &Mojarrad, J. S. (2015). Study on the feasibility of using natural cationic surfactants extracted from Olive, Spistan, and Prosopis plants to reduce the interfacial tension between kerosene and water. Journal of Surfactants and Detergents, 18(4), 739-746.
[10] IJeh I.I. ; Ejike C. E. C. C. (2011), “Current perspectives on the medicinal potential of Vernonia amygdalina Del”. J Med Plant Res. 5(7): 1051-1061
[11] Okafor N, Anichie G (1983), West African hop substitutes for sorghum lager, Brewing and Distillation International.; 13: 20-21.
[12] Morah, G.N. and Obiegbuna, J.E (2002). The effect of different pre-washing and washing treatment on some chemical and sensory properties of bitter leaf vegetables. Nigerian Food Journal 20: 52-57.
[13] Farombi, E. O., & Owoeye, O. (2011). Antioxidative and chemopreventive properties of Vernonia amygdalina and Garcinia biflavonoid. International journal of environmental research and public health, 8(6), 2533-2555.
[14] G Ayoola.A., Coker H. A. B., Adesegun S. A., Adepoju-Bello A. A., Obaweya K., Ezennia E. C., Atangbayila T. O. (2008). Phytochemical Screening and Antioxidant Activities of Some Selected Medicinal Plants Used for Malaria Therapy in Southwestern Nigeria.. Tropical Journal of Pharmaceutical Research, September 2008; 7(3): 1019-1024.
[15] Egharevba C. O., Osayemwenre E., Imieje V., Falodun A.. (2014). Significance of Bitter Leaf (Vernonia Amygdalina) In Tropical Diseases and Beyond: A Review. Malaria Chemotherapy, Control and Elimination.
[16] Huffman. et al. (2012). Further observations on the use of the medicinal plant, Vernonia amygdalina by a wild chimpanzee, its possible effect on parasite load, and its phytochemistry. African Study Monographs, 14, 227-240.
[17] Oboh F. O. J., Masodje H. I. (2009). Nutritional and Antimicrobial Properties of Vernonia amygdalina leaves. Journal of Biomedical and Health Sciences. Vol. 5, No. 2, June 30, 2009.
[18] Gberikon G. M. Ichor T. and Omeche E. T.. (2016). Effect of Bitter Leaf Extract (Vernonia amygdalina) on Culturable Microorganisms Isolated from Palm Wine in Makurdi Metropolis. Research Journal of Microbiology, 11: 112-118.
[19] Atangwho, I. J., Egbung E., Ahmad M., Yam M. F., Asmawi M. Z. (2013) “Antioxidant versus anti-diabetic properties of leaves from Vernonia amygdalina growing in Malaysia.” Food chemistry vol.: 3428-34.
[20] Ogbuagu, E. O., Airaodion A., Ogbuagu U., Airaodion E. O. (2019). Effect of Methanolic Extract of Vernonia amygdalina Leaves on Glycemic and Lipidaemic Indexes of Wistar Rats. Asian Journal of Research in Medical and Pharmaceutical Sciences, 7(3), 1-14.
[21] Oluwaseun Ruth Alara, Nour Hamid Abdurahman, Chinonso Ishmael Ukaegbu & Nassereldeen Ahmed Kabbashi (2019) Extraction and characterization of bioactive compounds in Vernonia amygdalina leaf ethanolic extract comparing Soxhlet and microwave-assisted extraction techniques, Journal of Taibah University for Science, 13: 1, 414-422,
[22] Ikpeseni S. C., Ogbue M. C., Okoh I. E., Ekpu M., Edomwonyi-Otu L. C. (2024). Empirical Assessment of African Oil Bean Husk as a Fluid-Loss Control Agent in Oil-Based Drilling Mud. American Journal of Chemical Engineering. Vol. 12, No. 3, pp. 52-64.
[23] Association of Official Analytical Chemists, AOAC, (1989) Official Methods of Analysis. 14th Edition, Association of Official Analytical Chemists, Washington DC.
[24] Tabasum S., Swati K., Jain K. (2016). Spectrophotometric quantification of total phenolic, flavonoid, and alkaloid contents of abrus precatorius L. Seeds. Journal of Pharmaceutical and Clinical Research 9(2): 371-374.
[25] Zhishen Jia, Mengcheng Tang, Jianming Wu (1999) The determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals. Food Chemistry, Volume 64, Issue 4, March 1999, Pages 555-559.
[26] DuBois M., Gilles K. A., Hamilton J. K., Rebers P. A., Smith F. (1956). Colorimetric Method for Determination of Sugars and Related Substances. Analytical ChemistryVol 28/Issue 3 Article March 1, 1956.
[27] Singleton V. L., Orthofer R., Lamuela-Raventós R. M. (1999). Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent - Methods in enzymology, 299, 152-178.
[28] Amott E. (1958). Observations Relating to the Wettability of Porous Rock. Society of Petroleum Engineers, SPE 1167-G.
[29] Cuiec L., Bourbiaux B., Klaydjian F. (1994): Oil recovery by imbibition in low-permeability chalk. SPE FE (Sep). Pp. 200-208.
[30] Ruth, M., Okeke, I. N., Ojeaga, T. H. (2021). Phytochemical composition and antioxidant activity of bitter leaf (Vernonia amygdalina) and its sap. Journal of Medicinal Plants Research, 15(2), 23-30.
[31] Ojeaga, T. H., Ogbole, O. A., & Adebayo, J. O. (2021). Comparative analysis of the phytochemical constituents of bitter leaf and its extracts. International Journal of Research in Pharmacy and Biosciences, 8(3), 1-7.
[32] Ogunlade, O. F., Adeyemi, I. A., & Oduola, O. A. (2022). Phytochemical screening and antimicrobial properties of bitter leaf extracts. Asian Journal of Pharmaceutical Research and Development, 10(1), 12-19.
[33] Zhang, Y., Liu, J., & Zhang, Q. (2021). The impact of carbonyl compounds on surface polarity and oil recovery efficiency. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 43(10), 1234-1243.
[34] Liu, Q., Yang, S., & Chen, F. (2020). Role of chemical functional groups in altering the wettability of sandstone for enhanced oil recovery. Energy & Fuels, 34(11), 13718-13729.
[35] Singh, P., Gupta, R., & Sharma, A. (2021). A review of the significance of hydroxyl and carbonyl groups in oil recovery processes. Journal of Molecular Liquids, 335, 116668.
[36] Zhou, L., Li, R., & Chen, W. (2022). Modification of surface properties in oil-water systems: Recent advancements and future directions. Journal of Petroleum Science and Engineering, 205, 108874.
[37] Guo, K., Zhang, J., Sun, H., & Xu, S. (2018). Understanding wettability alteration in nanopore confinement: A molecular dynamics simulation study. Journal of Physical Chemistry C, 122(12), 6496-6504.
[38] Liang C., Amelung W., Lehmann J., Kästner M. (2019) Quantitative assessment of microbial necromass contribution to soil organic matter. Institute of Applied Ecology.
[39] Zhang S., Wang T., Gao Z., Zhang Y. (2023). Wettability controlling effects on the fluid occurrence and flow in shale gas reservoirs: Present problems and new sights. Capillarity. Vol. 9, No. 2, p. 25-31, 2023.
[40] Xu, Z., Zhang, Y., & Li, X. (2020). The role of Periclase (MgO) in enhancing water-wetness in reservoirs. Journal of Natural Gas Science and Engineering, 75, 103038.
[41] Lashkarbolooki, M., M. Riazi, F. Hajibagheri, and S. Ayatollahi. (2016). Low salinity injection into asphaltenic-carbonate oil reservoir, mechanistical study. Journal of Molecular Liquids 216: 377-86.
[42] American Petroleum Institute, (2019) Certification. Standards. Safety. Events. Training. Statistics. Publications Programs Services 2019.
[43] Zallaghi M, Kharrat R, Hashemi A (2018) Improving the microscopic sweep efficiency of water flooding using silica nanoparticles. J Petrol Explor Prod Technol. 8: 259-269.
[44] Shikiai W, Leiting S, Zhongbin Y, Yaoyao W, Changlong L, Xinsheng X (2021) Microscopic experimental study on the sweep and displacement efficiencies in heterogeneous heavy oil reservoirs. Energy Reports 7, 1627-1635.
[45] Austad T., Standnes D. (2000): Wettability alteration in chalk 2. Mechanism for wettability alteration from oil-wet to water-wet using surfactants. Stavanger, Norway. h
[46] Chandio, T. A.; Manan, M. A.; Memon, K. R.; Abbas, G.; Abbasi, G. R. (2021): Enhanced oil recovery by hydrophilic silica nanofluid: Experimental evaluation of the impact of parameters and mechanisms on recovery potential. Energies 14, 5767 [CrossRef].
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    Ogbue, M. C., Okperhie, J., Adewole, E. S., Bello, K. O. (2025). Test on Bitter Leaf Sap as a Surfactant for Wettability Alterations in Enhanced Oil Recovery from Sand Aggregates. American Journal of Chemical Engineering, 13(3), 53-65. https://doi.org/10.11648/j.ajche.20251303.11

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    Ogbue, M. C.; Okperhie, J.; Adewole, E. S.; Bello, K. O. Test on Bitter Leaf Sap as a Surfactant for Wettability Alterations in Enhanced Oil Recovery from Sand Aggregates. Am. J. Chem. Eng. 2025, 13(3), 53-65. doi: 10.11648/j.ajche.20251303.11

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    AMA Style

    Ogbue MC, Okperhie J, Adewole ES, Bello KO. Test on Bitter Leaf Sap as a Surfactant for Wettability Alterations in Enhanced Oil Recovery from Sand Aggregates. Am J Chem Eng. 2025;13(3):53-65. doi: 10.11648/j.ajche.20251303.11

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  • @article{10.11648/j.ajche.20251303.11,
      author = {Michael Chukwunweike Ogbue and Johnbull Okperhie and Ezizanami Stephen Adewole and Kelani Olafinhan Bello},
      title = {Test on Bitter Leaf Sap as a Surfactant for Wettability Alterations in Enhanced Oil Recovery from Sand Aggregates
    },
      journal = {American Journal of Chemical Engineering},
      volume = {13},
      number = {3},
      pages = {53-65},
      doi = {10.11648/j.ajche.20251303.11},
      url = {https://doi.org/10.11648/j.ajche.20251303.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajche.20251303.11},
      abstract = {Alteration of reservoir-wettability is very important during Enhanced Oil Recovery (EOR) process since it helps to mobilize hydrocarbon and thus increase its recovery from the reservoirs. However, conventional wettability alteration agents used in the industry are inorganic chemicals which are expensive, constitute and have been found to be harmful to the environment. Hence, there was need for cheaper and environmentally-friendly alternative. Also, there was need to find more use for abundant local materials which have are under-utilized. In this article, bitter leaf sap (BLS) was studied to ascertain its possibilities as bio-surfactant for wettability alteration. In order to establish its phytochemical composition, BLS was analyzed using SEM, FT-IR, XRD, and XRF in accordance with ASTM standards. Wettability alteration capacity of three different concentrations of BLS solution on three sand aggregates was investigated. Active compounds which qualified BLS as bio-surfactant were identified from phytochemical analyses. Phytochemical analyses of BLS do not reveal any compounds that could be dangerous to the environment. The results from wettability tests obtained showed that core Sample A, (grain-size 0.118 cm) gave highest degree of wettability alteration with wettability index change from - 0.3030 to - 0.2020. Degree of wettability alteration increased as grain size of sand increased. It was also found that the degree of wettability alteration increased as concentration of BLS increased. Although, BLS could cause wettability alteration, its degree of alteration was lower than the degree of alteration of industrial wettability alteration agent.
    },
     year = {2025}
    }
    

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  • TY  - JOUR
    T1  - Test on Bitter Leaf Sap as a Surfactant for Wettability Alterations in Enhanced Oil Recovery from Sand Aggregates
    
    AU  - Michael Chukwunweike Ogbue
    AU  - Johnbull Okperhie
    AU  - Ezizanami Stephen Adewole
    AU  - Kelani Olafinhan Bello
    Y1  - 2025/06/20
    PY  - 2025
    N1  - https://doi.org/10.11648/j.ajche.20251303.11
    DO  - 10.11648/j.ajche.20251303.11
    T2  - American Journal of Chemical Engineering
    JF  - American Journal of Chemical Engineering
    JO  - American Journal of Chemical Engineering
    SP  - 53
    EP  - 65
    PB  - Science Publishing Group
    SN  - 2330-8613
    UR  - https://doi.org/10.11648/j.ajche.20251303.11
    AB  - Alteration of reservoir-wettability is very important during Enhanced Oil Recovery (EOR) process since it helps to mobilize hydrocarbon and thus increase its recovery from the reservoirs. However, conventional wettability alteration agents used in the industry are inorganic chemicals which are expensive, constitute and have been found to be harmful to the environment. Hence, there was need for cheaper and environmentally-friendly alternative. Also, there was need to find more use for abundant local materials which have are under-utilized. In this article, bitter leaf sap (BLS) was studied to ascertain its possibilities as bio-surfactant for wettability alteration. In order to establish its phytochemical composition, BLS was analyzed using SEM, FT-IR, XRD, and XRF in accordance with ASTM standards. Wettability alteration capacity of three different concentrations of BLS solution on three sand aggregates was investigated. Active compounds which qualified BLS as bio-surfactant were identified from phytochemical analyses. Phytochemical analyses of BLS do not reveal any compounds that could be dangerous to the environment. The results from wettability tests obtained showed that core Sample A, (grain-size 0.118 cm) gave highest degree of wettability alteration with wettability index change from - 0.3030 to - 0.2020. Degree of wettability alteration increased as grain size of sand increased. It was also found that the degree of wettability alteration increased as concentration of BLS increased. Although, BLS could cause wettability alteration, its degree of alteration was lower than the degree of alteration of industrial wettability alteration agent.
    
    VL  - 13
    IS  - 3
    ER  - 

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  • Abstract
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    1. 1. Introduction
    2. 2. Materials and Methods
    3. 3. Results and Discussion
    4. 4. Conclusion
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  • Author Contributions
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