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Water flooding has already been shown to be one of the most cost-effective ways to enhance oil recovery in carbonate reservoirs. The main obstacle of this type of reservoir is the low recovery rate due to the oil-wet rock surfaces and modifying the chemistry of water injection could significantly increase oil production. This article aimed at the optimization of salinity and composition of divalent ions in Smart water flooding in dolomite reservoir rocks. Contact angle measurements performed in two steps to screen and select the optimal composition among several types of waters. Core flooding experiments conducted to evaluate the performance of the chosen waters in two different scenarios; It was carried out in three steps including brine (FW) injection, followed by best water (RW) and finally smart water (RW2S) and the second scenario was applied in reverse. Maximum recovery of 59.65% original oil in place (OOIP) was recorded for the second scenario and a lower recovery of 50.72% OOIP was observed for the first. Experimental results confirms that a higher concentration of sulfate ions enhances the water-wetness of dolomite rocks and two main mechanisms behind the smart water injection are wettability alteration and pH increase. [ABSTRACT FROM AUTHOR]

Foamed cements are coarse dispersions of a base cement slurry, a gas (usually air or nitrogen), a foaming surfactant and other materials A new foamed cement, designed for oil/gas well liners and casing cementing jobs, was formulated. Ultra-lightweight cement pastes (such as foamed cements) are appropriate for formation damage prevention in fractured and depleted reservoirs. In this work, foamed cements were prepared at high shear rates using a foaming agent primarily composed of sodium lauryl ether sulfate, boric acid and a retarder (JR120). This formulation was called FBJ. The samples were subjected to tests for density, rheology, free water, settling, thickening time, compressive strength (CS), fluid loss, porosity and permeability, along with microscopic photography and computed tomography scanning. Compared with other drilling cements, the FBJ was found to have one of the lowest densities (1200 kg/m3), a CS of 8963 kPa and a thickening time of about 3 h. The rheology of the FBJ improved under high-pressure and high-temperature conditions. Examinations of the set FBJ also showed that the pores were not interconnected, the porosity of the FBJ was greater than 73% and 28% of the FBJ was matrix. Moreover, cement permeameter tests indicated that the permeability of the FBJ was just 0.0109 mD (1 mD ≈ 1 × 10−12 cm2). All of these results show that the formulated FBJ has acceptable properties for oil/gas wells cementing applications. [ABSTRACT FROM AUTHOR]

It is necessary to enhance oil production from reservoir due to increase of the fossil fuel consumption that results of industrial life development. Surfactant flooding is a popular method to enhance oil recovery by IFT reduction and wettability alteration. In this study, a new natural surfactant that extracted from Cordia myxa leaf is used for surfactant flooding. The effect of this natural surfactant on IFT and wettability is investigated experimentally. Then, surfactant flooding is applied in a carbonate core sample. The results show the IFT of solution was reduced from 33/28mN/M at 0 wt% to 16.24 mN/M at 6 wt% by increasing natural surfactant concentration. More than, contact angle was decreased from 137.05° at 0 wt. % to 130.65° at 5.5 wt. %. The core flooding results show C. myxa flooding increased 27% more oil recovery compared to water flooding and reduced residual oil saturation in porous media. The results show C. myxa can be applicable as a green surfactant for enhancing oil recovery. [ABSTRACT FROM AUTHOR]

The purpose of this study is to consider the wettability of rocks by a contrast between different types and concentration of surfactants, such as anionic, cationic and nonionic surfactants. Contact angle method is the wettability measurements method used in this study. Different types of surfactant and several concentrations of them gave a different angle of a drop on the sample surface. Results indicate that the cationic surfactant affects the contact angle into the water-wet state better than the others. The results of this study will give better plans to improving surfactant flooding performance in fractured and conventional reservoirs. [ABSTRACT FROM AUTHOR]

Oil recovery from oil-wet carbonate rock is a significant challenge in the oil industry. The present study investigates the influence of the natural surfactant Hawthorn leaves extract (HLE) on oil recovery from carbonate rock. Two chemical surfactants, sodium dodecyl sulfate (SDS) and dodecyl tri methyl ammonium bromide (DTAB), were used to validate and compare oil recovery with the new natural surfactant HLE. A wettability alteration test using the contact angle method, an interfacial test (IFT) using pendant drop, and core flooding were employed to investigate the behavior of the surfactants on oil recovery. The experimental results show that the critical micellar concentration (CMC) point of different concentrations of HLE, SDS, and DTAB solution occurs at 3.25, 3.00, and 4.06 wt %, respectively. In wettability alteration, the natural surfactant HLE is more effective than other chemical surfactants (SDS and DTAB) at the CMC point. As observed, the contact angle of the carbonate pellet and the HLE at the CMC point is 86°, and this angle for SDS and DTAB is 112° and 92°, respectively. The core flooding results show that the oil recovery factor improves from 37% with water flooding to 47.6% with SDS, 56.2% with DTAB, and 54.7% with HLE. The results prove that this new natural surfactant (HLE) can be used as a novel surfactant for the chemically enhanced oil recovery process in carbonate oil reservoirs. HLE has beneficial effects in oil recovery because of its environment friendly compared to SDS and DTAB. [ABSTRACT FROM AUTHOR]