Articles

Laboratory Investigation on Enhanced Oil Recovery Using Local Alkaline –Polymer for Niger – Delta Region

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Approximately sixty percent of crude oil still lay trapped in the reservoir even after primary and secondary recovery processes have been completed, hence the need for a method that further improves recovery. To increase oil recovery and encourage utilization of local content, locally source alkaline and polymer materials were used to improve oil recovery in this study. The local alkaline and polymer used are plantain peel ash and corn starch respectively. The efficiency of the plantain peel ash and corn starch solution were tested using different seven core samples. The core samples were individually flooded with brine (salt and water) for secondary recovery process and different concentrations of plantain peel ash and corn starch both in stand-alone and in combined form were used for tertiary recovery. The results obtained from the experimental work showed that sample-B5 with 0.2g of plantain peel ash and 0.2g of corn starch in 100ml of brine gave the highest cumulative recovery of 86% as to compare to samples B1 and B2 which has the cumulative recovery of 70% and 78% respectively. Sample-B7 which has the highest concentration of corn starch (0.4g/100ml) gave the lowest recovery of 65% due to polymer adsorption on the rock surfaces which alters the rock wettability. The assessment of formation damage was done by evaluating and determining the permeability change after tertiary flooding. The concentrations with plantain peel ash have reduced permeability change. These locally sourced materials can replace synthetic enhanced oil recovery (EOR) chemical when properly modified and refined, and they are also cheap and environmentally friendly.

 

Improving Oil Recovery Efficiency Using Corn starch as a Local Polymer for Enhanced Oil Recovery Processes

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Polymer flooding is a chemical enhanced oil recovery method that improves the recovery of oil by controlling the mobility of water to oil phase. It uses polymer solutions to increase the viscosity of the displacing water thereby decreasing water/oil mobility ratio (Speight, 2013). The volumetric and displacement sweep efficiencies are positively affected by polymer flooding. The viscosity of the aqueous phase is increased due to the molecular size and structure of the polymer used. The main objective of this research was to study the ability of cornstarch (local polymer) to recover additional oil after conventional water flooding. The objective was successfully achieved by injecting four different unconsolidated samples (sand pack) with cornstarch solution at varying concentration of 500ppm, 1000ppm, 3000ppm, and 9000ppm. From the results of the experiment conducted, it was deduced that Cornstarch has the ability to recover an additional volume of oil about half the volume of oil recovered during conventional water flooding (i.e. if 50% of oil initially in place was recovered during water flooding, cornstarch can recover an additional 25% of the residual oil after water flooding). Also, higher concentrations of cornstarch reduce the recovery factor due to polymer adsorption on the rock surfaces which alters the rock wettability. To reduce the adsorption effect of Cornstarch, it is recommended that the concentration of Cornstarch be measured after the flooding experiments for a better understanding of the adsorption mechanism of cornstarch.