Arsalan Ansari

A novel improved oil recovery approach for increasing capillary number by enhancing depth of penetration in abu dhabi carbonate reservoirs

During the last few decades, there has been a globa l increase in oil demand by 35%. Besides, the petroleum industry is faced with a number of challe nges when considering the reservoir such as low swe ep efficiency, formation damage and implementing costl y techniques to enhance and improve the oil recover y. Electrokinetic Low-concentration acid IOR (EK LCA-I OR) is one of the emerging IOR technologies, which involves the application of the Low-concentration a cidizing integrated with electrically enhanced oil recovery (EK-EOR). This research focusses on analyzing the e ffectiveness of the EK LCA-IOR process in Abu Dhabi carbonates, improving the capillary number and enha ncing depth of penetration. Core-flood tests were conducted by saturating Abu D habi carbonate core-plugs with medium crude oil in a specially designed core-flood setup at Abu Dhabi re se voir conditions. After the water flooding stage, EK LCAIOR was applied using varying voltage gradients and ci concentrations upto 1.2% HCl injected at the anode and transported by EK to the target producer (catho de). Moreover, the capillary number change, and Sin gle Energy CT Scan (SECTS) results were analyzed in ord er to observe the effect on rock-fluid interaction t control rock adsorption capacity through interfacial tensio and depth of penetration. Several correlations at reservoir conditions relate d o acid concentration, displacement efficiency an d permeability enhancement have shown that the applic ation of water flooding on the carbonate cores yiel ds an average oil recovery of 58%. An additional 17-28% o il recovery was enhanced by the application of EK L CAIOR recording a maximum oil displacement of 88%. In addition, EK LCA-IOR was shown to enhance the reservoir’s permeability by 53% on average across t he tested core-plugs. EK LCA-IOR also improves the capillary number by 500% in Water-wet core plugs an d 1500% in Oil-wet core plugs, mainly due to a decr ease in interfacial tension. This indicates the decrease in acid adsorption as acid is precisely transporte d to the targeted production well through the tortuous path with an increased depth of penetration as proven by the SECTS results where EK LCA-IOR has penetrated 60% o f core-length that revealed minor fractures, precis ely delivering the acid front throughout the core-plug. Finally, EK LCA-IOR enhances capillary number along with an increased depth of penetration while allow ing us to save on the OPEX by maintaining decreased power consumption while reducing the acid/water requireme nt upto 10 times. This study takes one step forward to wards the development of EK Low-concentration acid IOR method feasible for Abu Dhabi oil fields in order t o make smart water floods applicable for complex fr actured reservoirs of UAE.