For controlling the viscous fingering in wateralternating gas injection, addition of foam with formation water is more favorable. Use of foam surfactant is one potential solution for reducing gas mobility. The main objective of this research is to generate stable foam for gas mobility control using surfactant blend formulation. Surfactant blends synergistically exhibit better foaming properties than those of individual surfactants. Surfactant blends improve the foam stability and reduces the destabilizing effect of crude oil. Using foam stabilizers may improve foam stability and apparent viscosity; both of these factors are important for improving gas mobility. Alpha olefin Sulfonate (AOS C14-16 ) was selected as main surfactant, Octylphenol Ethylene Oxide (TX-100) and Lauryl Amido Propyl Amine oxide (LMDO) were selected as additives. Aqueous stability test was performed at 96°C. Foam stability test was performed in the absence and presence of crude oil. The foam stability and longevity was recorded above the liquid level. Liquid drainage and Foam half-life were noted with respect to time. The mobility reduction factor of three formulations was performed with CO 2 by using Berea sandstone cores at 96°C and 1400 psi. Experimental result showed that surfactant blend of 0.6 % AOS ? 0.6 % LMDO was more stable in presence of crude oil and reduced more gas mobility as compared to an individual surfactant of 0.6 % AOS. The maximum generated foam volume and foam half time indicated better performance of the foaming agent. The surfactant blend formulation plays an important role in controlling gas mobility. Strong stability by these formulations indicates that the foam surfactant formulation is of great significance in the field of enhanced oil recovery.

Asphaltene Precipitation and Deposition is a serious problem which can reduce the oil recovery by reducing reservoir permeability and altering the wettability. It can plug wells and flow lines through deposition and also cause separation difficulties at the separation facilities. Taking preventive measures are always a wise solution rather than attempting to resolve issues when they are occurred. This study proposes a strategy and provides the comprehensive review of the methodology required to predict and prevent Asphaltene Precipitation. Light crude oil samples were taken to be characterized for their thermodynamic properties. The saturation pressure and Asphaltene Onset Point (AOP) were measured at different pressures, temperatures and compositional changes using the Solid Detection System (SDS). Phase diagram and Asphaltene Precipitation Envelopes (APE) were developed. Cubic Plus Association (CPA) equation of state was used to develop the Asphaltene phase envelope using Multiflash (infochem). Titration technique was used to obtain the Asphaltene Floculation point (AFP) using the dead oil and n-Heptane as a precipitant. Effect of different inhibitors was then evaluated using the Solid Detection System (SDS) equipment using the titration technique. Rock-Inhibitor Compatibility was then checked in the reservoir core samples by performing the dynamic core flooding test in the laboratory. Conclusively, this strategy helps to enhance the reservoir performance by minimizing the asphaltene precipitation and will save the cost associated with the consequences of high asphaltene precipitation.

The aim of this research is to find the best suitable acid to acidize undamaged low permeable sandstone formation Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. Matrix acidizing may also be used to increase formation permeability in undamaged wells. The change may be up to 50 to 100% with the mud acid. For any acidizing process, the selection of acid (Formulation and Concentration) and the design (Pre-flush, Main Acid, After-flush) is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid-Hydrofluoric with Concentration (3% HF-12% HCl). This study presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric acid. The results are compared with the mud acid and the results analyzed are porosity, permeability, strength, color change and FESEM Analysis. All of these new combinations shows that these have the potential to be used as acidizing acids on sandstone formations.

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As more technologies to enhance oil production recovery are being developed, well stimulation has been introduced and it acts as one of the important roles to fulfil the demand of world for energy. Well stimulation is a well intervention performed on an oil or gas well to increase production by improving the flow of hydrocarbons from the drainage area into the well bore. Well stimulation generally uses fluids which create or enlarge the flow channels of formation so that it can overcome low permeability of formation. A most common and one of the most successful well stimulation is matrix acidizing. In matrix acidizing, acids are injected at matrix pressure below formation fracturing pressure. The permeability of formation will be increased either by removing the pore-plugging materials in the formation or by creating new or enlarged flow paths in the rock depending on the formation and acid types. The right type of acid or combination of acids must be used to remove the damage. Thus, careful acid choice and treatment design are critical for a successful matrix acidizing. This paper presents the results of laboratory investigation of different acid combinations: HF/HCl, HF/HCOOH, HF/H3PO4, HBF4/HCl and HBF4/HCOOH. Hydrofluoric acid and fluoboric acid are used to dissolve clays and feldspar, while hydrochloric acid, phosphoric acid and formic acid are added to control the speed of reaction to allow the maximum acid to penetrate the core sample and also act as a buffer to maintain pH of the solution. Different tests have been performed on the core samples before and after the acidizing to do the comparative study. The results analyzed are permeability, porosity, color change, strength and mineralogy. Most of the new combinations used in this research showed better results than mud acid. But overall it is clear that in coming future lot of work can be done on sandstone acidizing prospects.