**Abstract**

Surfactant injection is one of the types of chemical injections used in enhanced oil recovery (EOR) process. Surfactant can increase the interfacial tension between oil and water in the rock matrix. The surfactant used is an anionic surfactant, which is one of the lignosulfonate surfactants known as sodium lignosulfonate (SLS) surfactant derived from lignin. Bagasse is one of the raw materials having a high content of lignin (24–25%). The synthesized bagasse becomes lignosulfonate used as an isolation of lignin and transformed into sodium lignosulfonate by sulfonation process. Based on the characteristic test, the bagasse's SLS surfactant has some qualified characteristics which are a good aqueous stability, clear solution and not causing turbidity, and capability to form middle-phase microemulsion with light oil. Synthesized SLS has a hydrophilic– lipophilic balance (HLB) value of 11.6 which can be classified as oil in water (O/W) emulsion. Middle-phase emulsion as a characteristic SLS surfactant affects the performance of the SLS surfactant injection. So the use of sodium lignosulfonate surfactant synthesized from bagasse is a challenge to be developed further as a surfactant flooding.

**Keywords:** adsorption, bagasse, enhanced oil recovery, light oil, middle-phase emulsion, recovery factor, sodium lignosulfonate surfactant

### **1. Introduction**

Enhanced oil recovery is the process of increasing oil recovery by injecting liquid into a reservoir where the fluid can change the physical properties of oil that is still trapped inside it. One method used is chemical injection, using an anionic surfactant. Surfactants have the ability to increase the interfacial tension between oil and water in the rock matrix. The type of surfactant that is used for the EOR is lignosulfonate surfactant known as sodium lignosulfonate surfactant derived from lignin. One of the raw materials having a high content of lignin is bagasse, which contains 24–25% lignin.

The bagasse process becomes lignosulfonate becoming lignosulfonate uses isolation of lignin from bagasse, and the sulfonated lignin becomes sodium lignosulfonate. For sulfonation process sodium bisulfite (NaHSO3) as reagent can be used. This sulfonation aims to change the hydrophilicity of less polar lignin (insoluble in water) by substituting hydroxyl groups with sulfonate groups so that hydrophility increases [1].

In this study, lignin has been successfully isolated from dried bagasse, which was confirmed through the analysis results of Fourier-transform infrared (FTIR). The FTIR showed the spectrum of isolated lignin has the same characteristic within lignin standard, which contains substituted phenolic aromatic groups and aliphatic alkene groups [2]. Sodium lignosulfonate (SLS) surfactant from bagasse has the same characteristics within the sodium lignosulfonate standard, which comprises the absorption peaks corresponding with the stretching vibration of aromatic and aliphatic alkene functional groups, the stretching vibration of sulfonate groups, and the bending vibration of carboxylic groups [3].

Surfactants will spread in water and absorb at the interfacial tension between air and water or at the interfacial between oil and water. The surfactant is an amphiphilic organic compound, which contains a hydrophobic tail and a hydrophilic head. The aggregate shape may depend on the chemical structure of the surfactant, taking into account the balance of hydrophobic tail and hydrophilic head, known as HLB [4]. Hydrophilic and hydrophobic functions are to determine the emulsion of the system. The type of emulsion can be determined using the hydrophilic–lipophilic balance (HLB) test [5]. The value of HLB shows the tendency of surfactants to dissolve in water or oil to form O/W or W/O emulsion types. Low HLB indicates that the surfactant is more soluble in water, named W/O emulsion type. If the formation salinity is low, low HLB surfactant must be chosen, such that surfactants can make intermediate-phase microemulsions with low salinity. When the formation salinity is high, high HLB makes intermediate-phase microemulsions with high salinity. HLB is determined by calculating values for various molecular regions, giving results on a scale ranging from 0 to 20, for nonionic surfactants. The HLB value 0 corresponds to the total hydrophobic molecule, and the value 20 corresponds to a molecule consisting of a hydrophilic component. HLB values can be used to estimate the nature of surfactants. HLB calculations [6] can be determined by the following formula:

$$\text{HLB} = \text{2O} \ast (\text{M}\_{\text{h}}) / (\text{M}\_{\text{l}} + \text{M}\_{\text{h}}) \tag{1}$$

Mh = molecular weight of hydrophilic groups.

Ml = molecular weight of a hydrophobic or lipophilic group.

For surfactant classification as emulsifier in the O/W system, the surfactant should have a range of values between 8 and 18 **Tables 1** and **2** [6].

The definition of emulsion is a two-phase system in which one of the fluids is dispersed in another, in the form of small droplets [7]. There are two types of emulsions based on the type of liquid that function as internal or external phases, namely:


**Figure 1** explains about W/O emulsion or O/W emulsion. For W/O emulsion, the water is an internal phase and oil is an external phase. As for the O/W emulsion, the oil is an internal phase and water is an external phase.

Microemulsion can occur due to the equilibrium between hydrophiles (head) and lipophiles (tail) so that surface-active agents (surfactants) are formed and reduce interfacial tension. In systems with the same conditions between the number C belonging to crude oil and the surfactant components, there will be a balance between oil and water so that the hydrophilic component (head) of the surfactant

*Surfactant Flooding for EOR Using Sodium Lignosulfonate Synthesized from Bagasse DOI: http://dx.doi.org/10.5772/intechopen.88689*


### **Table 1.**

*Enhanced Oil Recovery Processes - New Technologies*

the bending vibration of carboxylic groups [3].

Mh = molecular weight of hydrophilic groups.

grains scattered into the water

droplets which are dispersed into oil

the oil is an internal phase and water is an external phase.

Ml = molecular weight of a hydrophobic or lipophilic group.

should have a range of values between 8 and 18 **Tables 1** and **2** [6].

For surfactant classification as emulsifier in the O/W system, the surfactant

The definition of emulsion is a two-phase system in which one of the fluids is dispersed in another, in the form of small droplets [7]. There are two types of emulsions based on the type of liquid that function as internal or external phases,

a.Oil in water (O/W)-type emulsion, which is an emulsion consisting of oil

b.Water in oil (W/O)-type emulsion, which is an emulsion consisting of water

**Figure 1** explains about W/O emulsion or O/W emulsion. For W/O emulsion, the water is an internal phase and oil is an external phase. As for the O/W emulsion,

Microemulsion can occur due to the equilibrium between hydrophiles (head) and lipophiles (tail) so that surface-active agents (surfactants) are formed and reduce interfacial tension. In systems with the same conditions between the number C belonging to crude oil and the surfactant components, there will be a balance between oil and water so that the hydrophilic component (head) of the surfactant

In this study, lignin has been successfully isolated from dried bagasse, which was confirmed through the analysis results of Fourier-transform infrared (FTIR). The FTIR showed the spectrum of isolated lignin has the same characteristic within lignin standard, which contains substituted phenolic aromatic groups and aliphatic alkene groups [2]. Sodium lignosulfonate (SLS) surfactant from bagasse has the same characteristics within the sodium lignosulfonate standard, which comprises the absorption peaks corresponding with the stretching vibration of aromatic and aliphatic alkene functional groups, the stretching vibration of sulfonate groups, and

Surfactants will spread in water and absorb at the interfacial tension between air and water or at the interfacial between oil and water. The surfactant is an amphiphilic organic compound, which contains a hydrophobic tail and a hydrophilic head. The aggregate shape may depend on the chemical structure of the surfactant, taking into account the balance of hydrophobic tail and hydrophilic head, known as HLB [4]. Hydrophilic and hydrophobic functions are to determine the emulsion of the system. The type of emulsion can be determined using the hydrophilic–lipophilic balance (HLB) test [5]. The value of HLB shows the tendency of surfactants to dissolve in water or oil to form O/W or W/O emulsion types. Low HLB indicates that the surfactant is more soluble in water, named W/O emulsion type. If the formation salinity is low, low HLB surfactant must be chosen, such that surfactants can make intermediate-phase microemulsions with low salinity. When the formation salinity is high, high HLB makes intermediate-phase microemulsions with high salinity. HLB is determined by calculating values for various molecular regions, giving results on a scale ranging from 0 to 20, for nonionic surfactants. The HLB value 0 corresponds to the total hydrophobic molecule, and the value 20 corresponds to a molecule consisting of a hydrophilic component. HLB values can be used to estimate the nature of surfactants. HLB calculations [6] can be determined by the following formula:

HLB = 20 ∗ (Mh)/ (Ml + Mh) (1)

**52**

namely:

*HLB value and its application [6].*


### **Table 2.**

*Required HLB for a number of applications [4].*

### **Figure 1.** *Oil and water formation forming microemulsion [8].*

will go to the surface and form a surface-active agent (surfactant). In a high-salinity oil-soluble surfactant system, there will be ionic strength that is identical to salinity where the hydrophilic (head) component of the surfactant is weak and the lipophile (tail) component is strong. So, in a system with high salinity, the hydrophilic component weakens, and the lipophilic component will be stronger so that a balance occurs in the system and a surface-active agent (surfactant) is formed. At high salinity, the salt component will make a balance between the components C of surfactant and oil, thereby strengthening the interaction between surfactants and oil. Salinity of the formation water affects the reduction of oil–water interfacial tension by surfactant.

The emulsion condition formed can be seen from the results of the phase behavior test, which is a test of mixing fluid reservoir with injection fluid.

Emulsions are made to obtain stable and flat preparations from mixtures which cannot mix together. The behavior of the mixed phase is strongly influenced by solvent water salinity, temperature, type and concentration of surfactant, and oil type. The type of emulsion is also determined by salinity, as shown in **Figure 2**. In the figure, the optimal emulsion is in the middle, where the emulsion occurs in the middle area between water (surfactant) and oil, called the middle-phase emulsion.

Observations of mixed-phase behavior between reservoir fluid and injection fluid can be classified as lower-phase emulsion, microemulsion (middle-phase emulsion), upper-phase emulsion, macroemulsion, and sediment. **Figure 3** can explain about the classification of emulsion. This test is carried out on surfactants dissolved in formation water and then mixed with crude oil. This test aims to get the right conditions for the surfactant by determining the exact salinity and type of emulsions that can mix with crude oil.

The emulsion formed indicates that in the system there is a decrease in interfacial tension between the surfactant and crude oil systems. This phase behavior test is strongly influenced by the salinity of formation water.

Increased salinity will reduce the solubility of anionic surfactants in formation water, because with increasing concentration, the surfactant electrolyte is released from the formation water system [9]. In the middle phase that forms microemulsions, it represents the condition of miscible displacement, whereas in the mixed phase which forms the upper-phase or lower-phase emulsion, it represents an immiscible displacement condition.

The emulsion formed can be an indicator of the IFT value of the system. A high IFT indicates an immiscible fluid, while a low IFT indicates a fluid is miscible.

**Figure 2.** *Emulsion type based on salinity [8].*

*Surfactant Flooding for EOR Using Sodium Lignosulfonate Synthesized from Bagasse DOI: http://dx.doi.org/10.5772/intechopen.88689*

**Figure 3.**

*Enhanced Oil Recovery Processes - New Technologies*

emulsions that can mix with crude oil.

immiscible displacement condition.

is strongly influenced by the salinity of formation water.

The emulsion condition formed can be seen from the results of the phase behav-

Emulsions are made to obtain stable and flat preparations from mixtures which cannot mix together. The behavior of the mixed phase is strongly influenced by solvent water salinity, temperature, type and concentration of surfactant, and oil type. The type of emulsion is also determined by salinity, as shown in **Figure 2**. In the figure, the optimal emulsion is in the middle, where the emulsion occurs in the middle area between water (surfactant) and oil, called the middle-phase emulsion. Observations of mixed-phase behavior between reservoir fluid and injection fluid can be classified as lower-phase emulsion, microemulsion (middle-phase emulsion), upper-phase emulsion, macroemulsion, and sediment. **Figure 3** can explain about the classification of emulsion. This test is carried out on surfactants dissolved in formation water and then mixed with crude oil. This test aims to get the right conditions for the surfactant by determining the exact salinity and type of

The emulsion formed indicates that in the system there is a decrease in interfacial tension between the surfactant and crude oil systems. This phase behavior test

Increased salinity will reduce the solubility of anionic surfactants in formation water, because with increasing concentration, the surfactant electrolyte is released from the formation water system [9]. In the middle phase that forms microemulsions, it represents the condition of miscible displacement, whereas in the mixed phase which forms the upper-phase or lower-phase emulsion, it represents an

The emulsion formed can be an indicator of the IFT value of the system. A high

IFT indicates an immiscible fluid, while a low IFT indicates a fluid is miscible.

ior test, which is a test of mixing fluid reservoir with injection fluid.

**54**

**Figure 2.**

*Emulsion type based on salinity [8].*

*Three types of microemulsion effect of salinity and phase behavior [5].*

IFT at surfactant and oil is a function of formation water salinity, temperature, surfactant concentration, type of surfactant, and oil type, while the phase behavior test is influenced by the type of oil, type of co-surfactant, temperature, structure of surfactant, and pressure [5]. The behavior of the microemulsion phase is very complex and depends on a number of parameters. Surfactants can form microemulsions because of their level of solubility that are both in water and in oil. There is no equation for simple microemulsions. Therefore, the phase behavior for certain microemulsion systems must be measured experimentally. The phase behavior of microemulsions is usually presented using ternary diagrams and empirical correlations. The ternary diagram is a very useful tool in EOR because it can simultaneously represent the composition of phases and the whole and relative numbers. **Figure 4** shows a ternary diagram schematic.

In the ternary diagram, the equilateral triangle represents the components of water, oil, and 100% surfactant from the solution. The concentration can be shown in mole fraction, mass, or volume. The single-phase region is in the zone of high surfactant concentration. The three-phase region is in the middle zone. The twophase lobes (vertices) are in the upper right and left over the three-phase triangle. There is a third two-phase region which is located at very low surfactant concentrations below the three-phase region. Type III ternary-phase behavior consists of an area close to the axis of salt water/oil which is bounded by a triangle. The composition in this area will produce three phases; the composition of each phase is the same as the composition of the curved triangular peak.

The microemulsion system can also be designed to obtain a very low IFT value, around 0.001 mN/m by making a stable brine solution or with a hydrocarbon phase [10] which will be advantageous for the EOR process. In the EOR process, an important part of the ternary diagram is the three-phase region. The general form of ternary diagram can be classified as type II (−), namely, lower-phase emulsion

and excess oil phase; type (+), namely, upper-phase emulsion with excess water phase; and type III, middle-phase microemulsion. The lowest interfacial tension occurs because the SLS surfactant can form a microemulsion.

The SLS surfactant from bagasse can function as an oil in water emulsion which means that the SLS surfactant is soluble in water but does not mix. For the certain salinity, NaCl will cause an effective reduction of the oil–water interfacial tension. This condition occurs in the proportion of 20,000 ppm, 4.5%; 40,000 ppm, 1.5%; and 40,000 ppm, 4%, where the increase in salt (NaCl) causes a decrease of interfacial tension and reduces oil recovery. In the proportion of salinity of 20,000 ppm, 4.5%, IFT is lower, but microemulsions are not formed, meaning that in this system the surfactant is not soluble in the oil. This condition causes the reduction of performance of bagasse SLS surfactant and produces less recovery factor of oil [11].

### **2. Methodology**

Bagasse is a by-product of the sugarcane liquid extraction process. Bagasse is one of the sources of biomass, whose utilization is currently mostly only as fuel in steam boilers, as raw materials of paper, or as a source of animal feed. The bagasse used is bagasse which has undergone the fifth milling process from the process of sugar (**Figure 5**) [11].

Bagasse mostly contains lignocellulose. The fiber length is between 1.7 and 2 mm with a diameter of about 20 μm. Bagasse contains 48–52% water, average sugar is 3.3%, and average fiber is 47.7%. Bagasse fiber is insoluble in water and consists mainly of cellulose, pentose, and lignin. Based on chemical analysis, the average bagasse has a chemical composition, namely, ash 3.28%, lignin 22.09%, cellulose 37.65%, juice 1.81%, pentosan 27.97%, and SiO2 3.01% [6].

The process of bagasse becomes lignosulfonate starting from the separation of lignin from bagasse and then reaction with sodium bisulfite to sodium lignosulfonate. The processing of bagasse to produce lignosulfonate was initially performed by isolation of lignin and the isolated lignin transformed into sodium lignosulfonate by sulfonation process. The process is using reflux equipment with a condenser and bagasse at 80 mesh in size. The lignin isolation process uses reflux for 4 h, with sodium hydroxide reagent. The lignin produced was then processed into lignosulfonate using sodium bisulfite reagent and refluxed for 4 h [11].


*Enhanced Oil Recovery Processes - New Technologies*

and excess oil phase; type (+), namely, upper-phase emulsion with excess water phase; and type III, middle-phase microemulsion. The lowest interfacial tension

The SLS surfactant from bagasse can function as an oil in water emulsion which means that the SLS surfactant is soluble in water but does not mix. For the certain salinity, NaCl will cause an effective reduction of the oil–water interfacial tension. This condition occurs in the proportion of 20,000 ppm, 4.5%; 40,000 ppm, 1.5%; and 40,000 ppm, 4%, where the increase in salt (NaCl) causes a decrease of interfacial tension and reduces oil recovery. In the proportion of salinity of 20,000 ppm, 4.5%, IFT is lower, but microemulsions are not formed, meaning that in this system the surfactant is not soluble in the oil. This condition causes the reduction of performance of bagasse SLS surfactant and produces less recovery factor of oil [11].

Bagasse is a by-product of the sugarcane liquid extraction process. Bagasse is one of the sources of biomass, whose utilization is currently mostly only as fuel in steam boilers, as raw materials of paper, or as a source of animal feed. The bagasse used is bagasse which has undergone the fifth milling process from the process of sugar (**Figure 5**) [11]. Bagasse mostly contains lignocellulose. The fiber length is between 1.7 and 2 mm with a diameter of about 20 μm. Bagasse contains 48–52% water, average sugar is 3.3%, and average fiber is 47.7%. Bagasse fiber is insoluble in water and consists mainly of cellulose, pentose, and lignin. Based on chemical analysis, the average bagasse has a chemical composition, namely, ash 3.28%, lignin 22.09%, cellulose

The process of bagasse becomes lignosulfonate starting from the separation of lignin from bagasse and then reaction with sodium bisulfite to sodium lignosulfonate. The processing of bagasse to produce lignosulfonate was initially performed by isolation of lignin and the isolated lignin transformed into sodium lignosulfonate by sulfonation process. The process is using reflux equipment with a condenser and bagasse at 80 mesh in size. The lignin isolation process uses reflux for 4 h, with sodium hydroxide reagent. The lignin produced was then processed into lignosulfo-

occurs because the SLS surfactant can form a microemulsion.

37.65%, juice 1.81%, pentosan 27.97%, and SiO2 3.01% [6].

nate using sodium bisulfite reagent and refluxed for 4 h [11].

**56**

**2. Methodology**

**Figure 4.**

*Ternary diagram schematic [5].*


### **Table 3.**

*Surfactant composition of concentration and salinity [11].*

Before use as laboratory-scale injection fluid, the SLS surfactant synthesized from bagasse was tested for its characteristics to match the fluid and reservoir rocks to be injected. A variation of surfactant concentration and variation of formation water salinity were used. The SLS surfactant synthesized from bagasse is injected into a 20% porosity and 100–500 mD Berea cores containing synthetic brine and light crude oil. The injection process with bagasse SLS surfactant has been carried out with variations in various proportions of salinity and surfactant concentration, as stated in **Table 3**.

The core injection process uses a surfactant solution of 1.5, 3.0, 4.0, and 4.5% with salinity of 5000, 10,000, 20,000, 40,000, and 80,000 ppm. The core injection uses core flood apparatus with Berea core synthesis in the core holder, shown in **Figure 6**. The core injection process consists of two stages: water injection and sodium lignosulfonate surfactant injection [11].

Before surfactant injection, cores were saturated with formation water using a vacuum system, until 100% saturated. Formation water is injected into the core with a variation of the flow rate, 0.5, 0.75, 1.0, and 1.5 cc/min, so that the core is filled with formation water. From this stage, effective water permeability (Kw) data will be obtained. In the next stage, crude oil is injected into the core with a variation of flow rate, 0.25, 0.5, 1.0, 1.5, and 2.0 cc/min, so the formation water is pushed out, and the core is filled with crude oil. From this stage, effective oil permeability (Ko) and connate water saturation (Swc) can be measured.
