ABSTRACT
Matrix acidizing is a technique that is widely used in the petroleum industry to remove scales and create channels in the rock. Removal of scales and creation of channels (wormhole) enhance productivity. Conventional acidizing fluids, such as hydrochloric acid (HCl) for carbonate and a mixture of hydrofluoric acid (HF) and HCl acid, are used for the matrix acidizing process. However, these fluids have some drawbacks, including strong acid strength, corrosion at high temperatures, and quick reactions with scale and particles. Emulsified acid systems (EASs) are used to address these drawbacks. EASs can create deeper and narrower wormholes by reducing the reaction rate of the acid due to the external oil phase. However, EASs have a much higher viscosity compared to conventional acidizing fluids. The high viscosity of EASs leads to a high drag that restricts pumping rates and consumes energy. This study aims to utilize environmentally friendly and widely available nanomaterials as drag-reducing agents (DRAs) of the EAS. The nanomaterials used in this study are carbon nanodots (CNDs). CNDs have unique properties and are used in diverse applications in different industries. The size of these CNDs is usually smaller than 10 nm. CNDs are characterized by their biocompatibility and chemical stability. This study investigates the use of CNDs as DRAs for EAS. Several experiments have been conducted to investigate the CNDs as a DRA for the EAS. The developed EAS was initially tested for conductivity and drop-test analysis to ensure the formation of an inverted emulsion. Thereafter, the thermal stability for the range of temperatures and the rheological properties of the EAS were evaluated to meet the criteria of field operation. Then flow experiments with EASs were conducted before and after adding the CNDs to investigate the efficacy of drag reduction of EASs. The results revealed that CNDs can be used as viscosity reducers for the EAS, where adding the CNDs to the EAS reduces the viscosity at two different HCl concentrations (15 and 20%). It reduces the viscosity of the EAS in the presence of corrosion inhibitors as well as other additives to the EAS, showing its compatibility with the field formulation. The drag reduction was observed at the range of temperatures investigated in the study. The conductivity, stability, and rheology experiments for the sample taken after the flow experiment are consistent, ensuring CNDs work as a DRA. The developed EAS with CNDs is robust in terms of field mixing procedures and thermally stable. The CNDs can be used as a DRA with EAS, which will reduce drag in pipes, increasing pumping rates and saving energy.
ABSTRACT
The dataset associate with the report is the flow experiment data acquired to evaluate the effect of density, viscosity, and surface tension on flow regime and pressure drop of two-phase flow in a horizontal pipe. To collect the data, experiments were conducted using a horizontal flow loop of 9.15 m (30 ft.) pipe length and 0.0254 m (1 inch) pipe diameter with a two-phase air/liquid system. The effect of surface tension was introduced by varying surface tension using the surfactant solution, the viscosity was varied using glycerin, and density was varied by the addition of calcium bromide. The superficial velocity of the liquid ranges from 0 to 3.048 m/sec (0-10 ft/s) and superficial gas velocity ranges from 0 to 18.288 m/sec (0-60 ft/s) respectively. The flow experiments were conducted at a constant liquid flow rate (fixing liquid rate) and varying the gas rate from minimum to the maximum value in a step-wise manner and then reducing the gas rate from maximum to minimum to see the presence of hysteresis effect. At each step of the experiment, the steady-state condition was observed based on the flow rate and pressure response and data were gather to have sufficient data points. Also, the video of the flow pattern was recorded using a high-speed camera for flow regime identification. Numerous sets of experiments were conducted to capture the ranges of superficial liquid and superficial gas velocity, density (1-1.5 gm/cc), viscosity (1-3.1 cP), and surface tension (32-70 mN/m). The data was used to develop the flow-regime map for the different cases and the effect of density, viscosity, and surface tension on flow regime and pressure drop were evaluated based on the boundary transition between different flow regimes. The pressure contour maps were generated to correlate with the flow regime map and their boundary transition. Also, a comparison of the generated data with the models in the literature is presented. Knowledge of flow regime type is essential for accurate prediction of the pressure drop in multiphase flow. However, to generate these maps a large quantity of experimental data is required and it is not feasible to evaluate the effect of each parameter on the flow regime map and boundary transition. This data-set is important in addressing the effect of fluid properties on two-phase horizontal flow also it will be a potential data-set for comparison as well as the development of multiphase flow modeling.
