Surfactant flooding, a chemical IOR technique is one of the viable EOR processes for recovering additional oil after water flooding. This is because it reduces the interfacial tension between the oil and water and allows trapped oil to be released for mobilization by a polymer.In this research, two sets of experiments were performed. First, the optimum surfactant concentration was determined through surfactant polymer flooding using a range of surfactant concentration of 0.1% to 0.6% and 15% of polymer. Secondly, another set of experiments to determine the optimum flow rate for surfactant flooding was carried out using the optimum surfactant concentration obtained. Lauryl Sulphate (Sodium Dodecyl Sulphate, SDS), an anionic surfactant, was used to alter the interfacial tension and reduce capillary pressure while Gum Arabic, an organic adhesive gotten from the hardened sap of the Acacia Senegal and Acacia Seyal trees, having a similar molecular structure and chemical characteristics with Xanthan Gum, was the polymer used to mobilize the oil.The results show that above 0.5%, oil recovery decreases with increase in concentration such that between 0.5 and 0.6%, a decrease of (20% -19%) is recorded. This suggests that it would be uneconomical to exceed surfactant concentration of 0.5%. It is shown in the result of the first set of experiments that a range of oil recovery of 59% to 76% for water flooding and a range of 11.64% to 20.02% additional oil recovery for surfactant Polymer flooding for a range of surfactant flow rate of surfactant concentration of 0.1% to 0.6%. For the second sets of experiments, a range of oil recovery of 64% to 68% for water flooding and a range of 15% to 24% additional oil recovery for surfactant flooding for a range of surfactant flow rate of surfactant flow rate of 1cc/min to 6cc/min. The Optimum surfactant flow rate resulting in the highest oil recovery for the chosen core size is 3cc/min. It's highly encouraged that the critical displacement rate is maintained to prevent the development of slug fingers.In summary, an optimum Surfactant flow rate is required for better performance of a Surfactant flooding.
Flocculation occurs when particles in the drilling fluid agglomerate due to particle to particle attraction thus leading to uneven distribution of weighting material within the fluid. Dispersants majorly are used to deffloculate fluids that have these tendencies, and their performance lies in the ability to minimize sagging and hence control drilling fluid rheology(Yusuf et al). This work was undertaken to investigate the effect of clay and sea water (containing calcium and magnesium ions) contaminations on dispersant performance used in an oil based invert emulsion drilling fluid system. Barite (Ba2SO4) was used as the weighting agent; the based fluid used for the oil based invert emulsion mud was EDC-99, a specialized kind, different from the conventional diesel oil.The fluid were analysed before and after aging using, rheometer, filtration and emulsion stability tests. The dispersant employed for the fluid system was Versathin ®. Versathin is an oligomeric fatty acid in mineral oil, an oil-based dispersant which tend to also perform excellently in the invert emulsion system. From the experimental results, a general decrease in fluid rheology was observed in the dispersant sample as compared with the blank sample. The emulsion stability of the fluid decreased as contaminants were added, fluid loss increased when contaminants were added to the dispersant samples. Contaminations also increased the plastic viscosity and yield point for the dispersant sample but all were still within the API range. Increase in LSYP in the presence of sea water and clay revealed that sag may be less noticeable when drilling reactive formations, confirming earlier studies on water based mud and the suitability of clay as rheology controllers. Cumulatively the result shows that Versathin oil based dispersant can control flow behaviour of fluids when employed in the oil based invert emulsion system.
High temperature variation in wells used in thermal oil recovery processes, deep gas wells, offshore wells with significant riser lengths and wells completed in abnormally hot reservoirs cause compaction of formations and this induces local compression and tensile stresses in the various casing strings cemented and landed in the well. Cemented wells are under various stresses and strains in various directions which can result in significant deformations and fracture. Therefore, casing failure or damage is inevitable largely due to thermally generated strains and stresses in the casing and the surrounding formation. This research studied the effect of the non-uniform loading (poroelastic effect) on stresses and failure of casing and cement by developing a Finite Element (FE) method for the analysis of temperature-stress interaction in three dimensions (3-D) for casing, cement and formation with all its complexities using ABAQUS simulation tool. The tool was used to develop temperature distribution and thermal stresses in the casing and near wellbore formation. This enabled possible casing failure predictions and provided theoretical basis for casing thermal stress failure by coupled temperature field and thermal stress field of casing.
A Well placement is a well-known technique in the oil and gas industry for production optimization and are generally classified into local and global methods. The use of simulation software often deployed under the direct optimization technique called global method. The production optimization of L-X field which is at primary recovery stage having five producing wells was the focus of this work. The attempt was to optimize L-X field using a well placement technique.The local methods are generally very efficient and require only a few forward simulations but can get stuck in a local optimal solution. The global methods avoid this problem but require many forward simulations. With the availability of simulator software, such problem can be reduced thus using the direct optimization method. After optimization an increase in recovery factor of over 20% was achieved. The results provided an improvement when compared with other existing methods from the literatures.
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