Surfactant Polymer (SP) flooding-a chemical EOR method, involves the injection of surfactants into the reservoir to reduce interfacial tension between oil and water and thus reduce capillary pressure for easy mobilization of oil. Polymers are also injected alongside to reduce mobility ratio and gather the oil droplet within the reservoir to create an oil bank and mobilize the oil towards the wellbore.In this paper, three different methods or mechanisms of implementing surfactant Polymer flooding were considered. Firstly, for Scheme or Method A, after water flooding, Sodium Dodecyl sulphate slug was injected then followed by gum Arabic slug. For Scheme B, a slug consisting of a mixture of Sodium Dodecyl sulphate and gum Arabic was injected after water flooding. In Scheme C, the core was first soaked with Sodium Dodecyl sulphate and then flooded with gum Arabic.The result showed a recovery of 56.25% of the water flooding residual oil for the first method while the other two Methods yielded displacement efficiencies of 66.12% and 64.4% respectively.In summary, the Mechanisms of implementing an SP flooding have some effects on the Oil recovery and as such care must be taken in selecting the mechanism to be adopted so as to optimize recovery.
The linear core flood (physical model) has been used severally in the past to conduct laboratory researches and experiments on Tertiary Oil Recovery. A potential pitfall of the 1D nature of the linear core flood arises during waterflooding; water channels would be blocked due to limited pathways, hence producing the additional oil before chemical consequently breaks through. In real reservoirs, there are more water pathways present; hence the relative impact of these chemical additives on incremental oil recovery is potentially overly emphasized in the laboratory. This paper presents a study on heavy oil production using chemicals in a locally fabricated 2D Hele-Shaw cell system. The 2D nature of the cell also aids the visualization of non-linear flow pathways. The experiments are run for a constant pore volume (5PV) flooding of Brine, Surfactant slug and Surfactant-Polymer (SP) slug. Recovery and digital images are taken at a minute interval each, thereby making it easier to study growth and distribution of fingers before and after water or chemical breakthrough. It was observed that after the 5PV of waterflooding, the recovery of oil from the cell reduced gradually till there was no more recovery. The Surfactant slug increased recovery by additional 21%. The more viscous Surfactant-Polymer slug gave an even improved and better recovery. This can be attributed to a clear interaction between the Surfactant and Polymer chemicals in the SP slug. The distribution of fingers between the different phases of flooding were visually observed and compared.
Polymer play a key role in several EOR processes such as polymer flooding, surfactant-polymer flooding and alkaline-surfactant-polymer flooding due to their critical importance of mobility control in achieving high oil recovery. This high oil recovery is dependent on polymer properties and the rate of flooding. This paper presents the results of polymer flooding of an unconsolidated porous media using the locally available Gum Arabic in its natural and Modified states. Commonly used polymers Xantham Gum and Hengfloc were also used for comparison. The effective flooding rate was established using Modified Gum Arabic as the polymer. The established flow rate was used in polymer flooding for other polymers. Different concentration of each polymer was used to achieve similar viscosity of polymer solutions used for each flooding. The brine, oil and porous media properties were also kept constant. The results from these studies favoured a low injection rate. More oil up to 90% of original oil in place was recovered. The result from the oil recovery using the established effective rate on other polymers showed that the Modified Gum Arabic recovers approximately 10% more than the natural Gun Arabic, Xantham Gum and Hengfloc. The recoveries were 90.2%, 81%, 79.5% and 80.2%, respectively. It was also observed that the oil retention time in polymer mixture is lower in Modified Gum Arabic and Natural Gum Arabic when compared to Xantham Gum and Hengfloc.
This paper presents laboratory analysis of optimum surfactant concentration needed for Niger delta oil recovery in Nigeria. Eight experiments were carried out on a crude sample from the field with different surfactant concentrations to water (0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5% surfactant) using glass beads to simulate the actual field process. Brine saturation, oil saturation, water flooding, surfactant flooding and polymer flooding were done for each of the eight experiments performed and the resulting recoveries were analysed and compared. Then, the optimum surfactant concentration was identified. The results show that 0.9% surfactant concentration is the optimum concentration needed for flooding in this field. Any concentration more than or less than 0.9% would yield less than the optimum recovery. It would be uneconomical to maintain a surfactant concentration higher than 0.9%. Recovery does not necessarily increase with increasing surfactant concentration in the mobilising slug. The field operators in this field are hereby advised to consider 0.9% surfactant concentration.
Relative permeability is one of the key factors in reservoir engineering calculations to simulate multiphase behavior in porous media. The relative permeabilities calculated from established models do not perfectly characterize the reservoir without a known trend or history. This necessitates the need to use a reliable and globally accepted technique based on Niger Delta field production data for calculating relative permeabilities from the fields so that the models derived from the relative permeability curves could be tamed and domesticated in the region for better reservoir characterization and evaluation. The Johnson, Bossler and Neumann (JBN) method is the industry standard for measuring relative permeabilities from field cores. In order to eliminate the need of using numerical differentiation, and therefore reduce the overall numerical error in this method, a graphical technique was proposed and implemented during late 70s. However, with splines, the numerical differentiations are still done but with improved results. The current study presents the results from the comparative analysis of two approaches employed to avoid the traditional numerical differentiation required by the JBN method. Production data from field cores in the Niger Delta were used. The graphical method and cubic spline numerical modeling were both used to calculate the individual relative permeabilities from the pressure/production history of the displacements. the results were analyzed and compared. The results of both methods show a very good match over a fairly small saturation range and also differ. However, cubic spline results are closer to the traditional numerical differentiation results because is a modeling approach in which the numerical differentiation is incorporated with improved accuracy.
Among the world's natural sources of energy, petroleum stands out as the largest contributing mineral. This makes it the most sought-after mineral. Methods for oil recovery are constantly studied, and innovations are being made to improve the recovery of oil. Chemical Enhanced oil recovery (EOR) process is therefore at the fore-front of these studies and innovations.The research work presents a comparative study of the core flooding carried out with different Alkali/Surfactant/Polymer (ASP) slugs formulated using sodium hydroxide (NaOH) an alkaline, surfactant being Lauryl Sulphate and Shell Enordet and polymer-gum Arabic and Xanthan gum.The result shows that the ASP slug of Xanthan gum with Shell Enordet 0242 and Lauryl Sulphate had the highest displacement efficiency of 71.23% and 49.51% respectively. The others ASP slug formulated with gum Arabic and Shell Enordet or Lauryl Sulphate gave an efficiency of 31.36% and 32.20% respectively.For heavy Oil recovery, the use of Shell Enordet 0242 or Lauryl Sulphate and Xanthan gum or gum Arabic will improve recovery. However, Xanthan gum gave a more stable displacement front than gum Arabic. Therefore, a higher concentration of gum Arabic is recommended for better recovery.
Based on Welge's solution of the flow equation, a method (JBN technique) to calculate the individual phase relative permeabilities from displacement data was developed for the first time in 1959. It's the most commonly used data reduction method for obtaining relative permeability relationships from unsteady state data. Similar to the Welge method, differentiation of data is required and negligible capillary end effects are assumed when using the JBN method. To apply the JBN method, information on pore volumes of fluids injected and produced, the pressure drop across the porous medium and fluid viscosities is needed. This method generally gives relative permeabilities over a fairly small saturation range, which varies depending on the relative mobilities of the flowing fluids. In order to improve the results of this method, many researchers have come up with different techniques in their JBN analysis including the cubic spline numerical modeling technique (CSNMT) discussed in this research. This paper presents relative permeability data obtained from comparative analysis of the JBN method with different approaches. The differentials of second order Lagrange interpolating polynomial and cubic spline numerical modeling technique (CSNMT) were all considered in the JBN analysis. The relative permeability curves were then analyzed and the best method was chosen. The results of all the different methods employed in the JBN analysis do not match perfectly throughout the entire saturation range. The errors in the use of the differentials of second order Lagrange interpolating polynomial on more than three data point are very substantial. The results obtained from the application of cubic splines are more representative of the relative permeabilities from the field cores.
In this work, we present extensive study of Alkaline-Surfactant-Polymer (ASP) flooding in reduction of residual oil saturation in both core plugs and heterogeneous beads-packs. During the ASP flooding of the core plugs, the effectiveness of the ASP flooding EOR technique on a typical Niger Delta reservoir core and other model cores and the determination of the rock properties that most affect the displacement efficiencies of the processes were analyzed. And in the beads-pack flood test, the potential of the ASP slug for oil recovery, the effect of heterogeneity on the oil recovery efficiency of the process and the investigation of the displacement efficiency of Hengfloc in ASP slug for recovery of Niger Delta oil were all analyzed. Finally, the performance in both was comparatively examined. In the ASP Flooding for beadspack, four different beadspack labeled as W, X, Y and Z were used in the experiment. For core flood test, four different core samples termed A1, B1 T1 and R1 used. For each type of porous media, Brine saturation, oil saturation, water flooding and SP flooding were all carried out on different core samples. The results show that the oil recovery by the imbibition process does not follow a regular pattern. It reveals some complexities in the oil mobilization process and an uneven pattern in the oil recovery due the simulated reservoir heterogeneity. It shows that it's not only the grain size of the reservoir rock but also the arrangement of the grains in the core affect the oil recovery. Water flooding can recover about 70% while ASP flooding can recover between 16 to 19% of the original oil in place from the synthesized heterogeneous beads pack. Bernheimer core gives the best results for ASP EOR flooding operations.
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