Mechanistic studies for improved understanding of low salinity waterflooding based enhanced oil recovery and potential application to the Alaskan North Slope reservoirs

Thesis (M.S.) University of Alaska Fairbanks, 2015Improvement in the recovery of oil by low or reduced salinity water has been reported by many researchers. However, a consistent mechanistic explanation behind low salinity waterflood has not yet emerged. A thorough literature review was conducted that pertains to low salinity water based enhanced oil recovery and preliminary screening criteria were proposed which may help in narrowing down the responsible mechanisms and identifying suitable candidates for low salinity waterflood. Altogether nine different variables, such as clays, oil characteristics, salinity ranges etc. were considered in developing the screening criteria. With the exception of some tests on standard Berea sandstone cores, all other experimental studies were carried out on representative Alaska North Slope (ANS) reservoir core samples and oil and brine samples. Experimental studies involved a direct visualization of the release of crude oil from the clay surface with low salinity waterflood as observed through a simple substrate type test. Amott type spontaneous displacement tests were performed to quantitatively determine the effect of low salinity water using core materials containing different types of clays. Two sets of low salinity water coreflooding experiments were conducted in the tertiary recovery mode; first using dead oil and the second using recombined oil at pseudo reservoir conditions to examine the potential in improving oil recovery. Oil recoveries were also compared with continuous injection vs slug-wise injection of low salinity water. Finally, surface level investigation was performed using an optical microscope to visually analyze the impact of low salinity water on core samples. All the experiments performed with low salinity water on Alaska North Slope (ANS) reservoir core samples consistently showed anywhere between a 3-30 % increase in oil production with the use of low salinity brine. The literature review identified wettability alteration, cation exchange capacity, clay type and clay content as some of the dominant mechanisms influencing low salinity waterflooding

HYRA gas-filled separator coupled to 4π spin spectrometer at IUAC, New Delhi

The Hybrid Recoil mass Analyzer (HYRA) operated in gas-filled mode has recently been coupled with the TIFR 4π spin spectrometer at IUAC, New Delhi to carry out spin (or angular momentum) distribution of heavy residues from fusion-evaporation reactions and spin gated GDR measurements. The details of the combined facility, initial experiments on evaporation residue tagged γ-multiplicity and the extraction of average transmission efficiency of HYRA are elaborated

Entrance channel effect for CN 200Pb

The spin distribution of Evaporation Residues (ER) was measured for the reaction 30Si + 170Er. ER spin distributions were compared for the systems 16O + 184W, 19F + 181Ta and 30Si + 170Er forming the Compound Nucleus 200Pb. Mean gamma multiplicity vs. excitation energy curve shows saturation at a lower value in case of 30Si + 170Er. This was attributed to non compound nuclear processes