Petroleum Engineering
Yaser Ahmadi
Abstract
Recently nanoparticles are used for improving the volume of oil and gas production and Enhanced Oil Recovery (EOR) purposes. Based on our recent researches, using nanoparticles such as Silica and Calcium oxide has a good potential for changing mechanisms in the porous media such as interfacial tension ...
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Recently nanoparticles are used for improving the volume of oil and gas production and Enhanced Oil Recovery (EOR) purposes. Based on our recent researches, using nanoparticles such as Silica and Calcium oxide has a good potential for changing mechanisms in the porous media such as interfacial tension and wettability. For finding the application of nanoparticles in the porous media, low permeability carbonate plugs were selected, and two main steps were used , including 1) Using CaO and SiO2 nanoparticles for wettability alteration, interfacial tension reduction, and improving fluid flow through porous media 2) Surveying the application of nanoparticles on the water alternative gas (NCs assisted WAG) test. The Zeta potential amounts are stable at condition of -56.4±2 mV and -44.0±3 mV for Calcium oxide and Silica nanoparticles, respectively at optimum nanoparticles concentration of 15 ppm. Calcium oxide and Silica nanoparticles have effectively altered the wettability from oil-wet to water-wet by surveying the intersection of two-phase relative permeability. Moreover, CaO nanoparticles had better performance in low permeability carbonate porous media than SiO2 nanoparticles with regards to wettability alteration to water wet. Based on the results and better version of CaO, it was selected for performing NCs assisted WAG tests at WAG ratios of 1:1, 40 ℃, and 15 ppm.The recovery factor was increased from 42.9 % to 73 % in the presence of CaO during performing NCs assisted WAG tests, and residual oil saturation was decreased from 40.9 % to 19.4 %.
Hadi Zolfaghari; Alireza Zebarjadi; Omid Shahrokhi; Mohammad Hosein Ghazanfari
Abstract
Several studies have shown that oil recovery significantly increased by low salinity water flooding (LSWF) in sandstones. However, mechanism of oil recovery improvement is still controversial. CO2 that develops buffer in presence of water is expected as a deterrent factor in LSWF efficiency based on ...
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Several studies have shown that oil recovery significantly increased by low salinity water flooding (LSWF) in sandstones. However, mechanism of oil recovery improvement is still controversial. CO2 that develops buffer in presence of water is expected as a deterrent factor in LSWF efficiency based on mechanism of IFT reduction due to pH uprising. No bright evidence in literature supports this idea. Here, a set of core floods including a pair of CO2 WAG and a pair of water injection tests are conducted and, the efficiency of LSWF and high salinity water flooding (HSWF) were compared for each pair. HSWF was followed by LSWF in tertiary mode. Results showed that not only CO2 does not deteriorate LSWF recovery efficiency, but also improves recovery. Since CO2-low salinity WAG showed best performance among types by constant pore volume injected. Positive results in both secondary and tertiary modes with Kaolinite free samples used here showed that Kaolinite release is not the critical phenomenon in LSWF brisk performance. Also different pressure behaviour of CO2 WAG processes in comparison with reported behaviour of LSWF proves that LSWF performance may not depend on how pressure changes through flooding.