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Norman R. Morrow - One of the best experts on this subject based on the ideXlab platform.
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Scaling Of Viscosity Ratio For Oil Recovery By Imbibition From Mixed-wet Rocks
Petrophysics, 2020Co-Authors: Zhengxin Tong, Norman R. MorrowAbstract:Displacement of oil by spontaneous imbibition from the rock matrix of fractured reservoirs can be a dominant production mechanism. Laboratory tests on reservoir cores are often used to predict oil recovery from the reservoir by scaling results to reservoir conditions. Factors involved in scaling are the rock properties, liquid viscosities, interfacial tensions, core geometry and wettability. Some previous developments in scaling were based on oil recovery from very strongly Water-wet rocks (VSWW); results for different viscosity ratios were closely correlated by the geometric mean of the oil and aqueous phase viscosities. Most reservoirs have mixed wettability (MXW), and, as judged from rate and extent of imbibition, many are weakly Water-wet. Results have been obtained for mixed-wet sandstone prepared by adsorption from an asphaltic crude oil. The crude oil used to induce wettability change was displaced by decalin followed by mineral oil. The MXW states attained by this technique depended on the aging temperature, the Initial Water Saturation, and the number of pore volumes of decalin used to displace the crude oil. For MXW cores prepared by this technique, imbibition rates were much slower than for strongly Water-wet cores and were highly sensitive to Initial Water Saturation. A series of imbibition tests were performed with Initial Water Saturation ranging from 11.0% to 28.0%. MXW imbibition results for recovery of mineral oil, with viscosities ranging from 3.8 to 180.0 cp and Initial Water Saturation close to 21%, were correlated satisfactorily by the geometric mean of the viscosity ratio.
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Spontaneous imbibition for mixed-wettability states in sandstones induced by adsorption from crude oil
Journal of Petroleum Science and Engineering, 2003Co-Authors: Zhengxin Tong, Norman R. MorrowAbstract:Abstract Wettability control by methods that are of practical relevance to oil recovery is an ongoing problem in wettability research. The preparation of mixed-wettability cores by adsorption from an asphaltic crude oil at elevated temperature and pressure has been investigated. After aging, crude oil was displaced by flow of decalin, an intermediate solvent that was compatible with the crude oil with respect to asphaltene precipitation but not likely to cause undue desorption of polar components of crude oil from pore walls. The decalin was in turn removed by flow of refined oil. In tests of the stability of the induced wetting states obtained by this approach, imbibition measurements were repeated for up to six cycles of imbibition and drainage. In most cases, wettability changed slightly towards Water wetness after the first cycle, but there was comparatively little or no change for further cycles of spontaneous imbibition and forced drainage. Factors in preparation of mixed-wet cores such as the volume of decalin used to flush crude oil from the core and the temperature of flushing were investigated during the course of development of the experimental procedures. Once established, the induced wetting states were stable with respect to further flushing with decalin and also to flushing with toluene, a stronger solvent for asphaltenes. In experiments on displacement of brine by high viscosity refined oils, the Initial Water Saturation of mixed wet cores could be readily reduced to much lower values than the Water Saturation that was present at the time of aging. However, in contrast to the drastic reduction in imbibition rate for cores aged at low Water Saturation, low Initial Water Saturation obtained by this means had very little effect on subsequent spontaneous imbibition. This observation is consistent with the concept of mixed wettability postulated by Salathiel (1973) [JPT (1973) 12616] that the distribution of Water at the time of aging controls the distribution of adsorbed components of crude oil.
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Oil Recovery By Spontaneous Imbibition From Weakly Water-wet Rocks
Petrophysics, 2001Co-Authors: Norman R. MorrowAbstract:Spontaneous imbibition is of special importance to oil recovery from fractured reservoirs. Laboratory measurements of volume of liquid imbibed versus time are often used in the prediction of oil recovery. Imbibition measurements also provide a useful approach to the complex problem of characterizing the wetting properties of porous media. Correlation of a large body of data for imbibition of brine into porous media Initially saturated with refined oil was achieved through a semi-empirical scaling group which includes permeability, porosity, interfacial tension, oil and brine viscosity, and the size, shape and boundary conditions of the sample. The objective of the present study was to test this correlation for samples of different geometry for spontaneous imbibition under weakly Water-wet conditions established by adsorption from crude oil with Initial Water Saturation ranging from 14% to 31%. After establishing Initial Water Saturations, the wettability of thirty-two core samples was changed to weakly Water-wet by aging in an asphaltic crude oil at elevated temperature. Initial Water Saturation had a dominant effect on rate of oil recovery. Times for imbibition decreased by about 2 to 4 orders of magnitude with decrease in Initial Water Saturation. Results for cores with the same Initial Water Saturation but of different size and shape (cylindrical, annular, and rectangular) and boundary conditions (given by sealing off part of the rock surface with epoxy resin) were closely correlated. The presence of epoxy resin during aging in crude oil enhanced the decrease in Water-wetness attained for cores and crude oil alone. The contribution to oil recovery by gravity segregation at very weakly Water-wet conditions is addressed.
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interrelationship of wettability Initial Water Saturation aging time and oil recovery by spontaneous imbibition and Waterflooding
Spe Journal, 2000Co-Authors: Xianmin Zhou, Norman R. MorrowAbstract:Previous studies of crude oil/brine/rock ~COBR! and related systems showed that wettability and its effect on oil recovery depend on numerous complex interactions. In the present work, the wettability of COBR systems prepared using Prudhoe Bay crude oil, a synthetic formation brine, and Berea Sandstone was varied by systematic change in Initial Water Saturation and length of aging time at reservoir temperature ~88°C!. All displacement tests were run at ambient temperature. Various degrees of Water wetness were achieved and quantified by a modified Amott wettability index to Water, the relative pseudowork of imbibition, and a newly defined apparent advancing dynamic contact angle. Pairs of spontaneous imbibition ~oil recovery by spontaneous imbibition of Water! and Waterflood ~oil recovery vs. pore volumes of Water injected! curves were measured for each of the induced wetting states. Several trends were observed. Imbibition rate, and hence, Water wetness, decreased with increase in aging time and with decrease in Initial Water Saturation. Breakthrough recoveries and final oil recovery by Waterflooding increased with decrease in Water wetness. Correlations between Water wetness and oil recovery by Waterflooding and spontaneous imbibition are presented.
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Influence of brine composition and fines migration on crude oil/brine/rock interactions and oil recovery
Journal of Petroleum Science and Engineering, 1999Co-Authors: Guo Qing Tang, Norman R. MorrowAbstract:Increase in recovery of crude oil with decrease in salinity has been observed for numerous laboratory Waterfloods. Repeated Waterfloods on a single reservoir sandstone core indicated that potentially mobile fine particles play a key role in the sensitivity of oil recovery to salinity. This conclusion was tested using Berea sandstone after fines had been stabilized by firing at 800°C and metal oxides removed by acidizing. Recovery of crude oil from this fired and acidized sandstone was essentially independent of salinity. The presence of crude oil was also a necessary condition for sensitivity to salinity. When refined oil was used rather than crude oil, with all other conditions held the same, salinity had no effect on recovery. There was also no effect for cores that were Initially 100% saturated with crude oil so that the fines were Initially immersed in the oil phase. Adsorption from crude oil, the presence of potentially mobile fines, and Initial Water Saturation are all necessary conditions for increase in oil recovery with decrease in salinity. Observed recovery behavior is ascribed to partial stripping of mixed-wet fines from pore walls during the course of Waterflooding. (C) 1999 Elsevier Science B.V. All rights reserved.
A Firoozabadi - One of the best experts on this subject based on the ideXlab platform.
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Gas/oil ratio, temperature, and Initial Water-Saturation effects on solution-gas drive
2020Co-Authors: G Tank, A FiroozabadiAbstract:The effects of Initial Water Saturation, S wi , temperature, and gas/oil ratio (GOR) on solution-gas drive in heavy oils were studied. The viscosity and gravity of the stock-tank oil used in the tests were 560,000 cp and 8.7°API. In two tests, 4.0 and 5.2% S wi were used. Five tests were conducted at 35°C, and one test was conducted at 46°C.
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Macro- and Microscale Waterflooding Performances of Crudes which form w/o Emulsions upon Mixing with Brines
Energy & Fuels, 2014Co-Authors: Nima Rezaei, A FiroozabadiAbstract:We study the micro- and macroscale Waterflooding performances of unusual crudes which naturally form tight emulsions (stable after 15 months) upon mixing with Water and different brines—including the reservoir brine. These crudes are obtained from a large oil field with stock tank oil viscosities in the range 20–100 cP. The Waterflooding tests are conducted at constant injection rates in Berea cores and also in a glass-etched micromodel with and without Initial Water Saturation. With the Initial Water Saturation, the emulsions cause final oil recovery to be significantly lower while the breakthrough is surprisingly suppressed. Pressure data suggests that emulsions are formed in situ in the Waterflooding tests both with and without the Initial Water Saturation. The injection pressure data show significant fluctuations after about 3 pore volumes of injection. Both the pressure drop and pressure fluctuations are found to be higher at lower injection rates. Furthermore, the pressure drop is higher in tests wi...
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effect of gor temperature and Initial Water Saturation on solution gas drive in heavy oil reservoirs
Spe Journal, 2005Co-Authors: G Tang, A FiroozabadiAbstract:We have carried out an extensive set of tests on solution-gas drive for a heavy oil to study the effects of Initial Water Saturation, temperature, and gas-oil ratio (GOR). The viscosity and the API gravity of the stock-tank oil from Hamaca field (in Venezuela) used in our tests are 560,000 cp (at 24°C) and 8.7, respectively. The solution-gas drive tests were conducted using live oils with solution GOR of 6.5, 9.0, and 12.2 (vol/vol at standard conditions). In two tests, Initial Water Saturations of 4.0 and 5.2% were established. Five tests were conducted at a temperature of 35°C; one test was conducted at 46°C. The duration for each test was approximately 3 months. The following conclusions are drawn based on the results from all the tests. Initial Water Saturation decreases gas-bubble density. The recovery efficiency decreases because of an increase in gas mobility with increase in Initial Water Saturation. As the temperature increases from 35 to 46°C, the gas relative permeability increases one order of magnitude, which in turn results in a reduction of recovery efficiency. The temperature effect on recovery is in agreement with our previous work with temperature increase from 24 to 35°C. Increase in solution GOR has a significant effect on the gas-bubble nucleation process, mainly because of change in interfacial tension. For all the tests conducted, the oil recovery by solution-gas drive at test termination was approximately 16% and higher.
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gas oil ratio temperature and Initial Water Saturation effects on solution gas drive
2001 SPE Annual Technical Conference and Exhibition, 2002Co-Authors: G Tank, A FiroozabadiAbstract:The effects of Initial Water Saturation, S wi , temperature, and gas/oil ratio (GOR) on solution-gas drive in heavy oils were studied. The viscosity and gravity of the stock-tank oil used in the tests were 560,000 cp and 8.7°API. In two tests, 4.0 and 5.2% S wi were used. Five tests were conducted at 35°C, and one test was conducted at 46°C.
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effect of pressure gradient and Initial Water Saturation on Water injection in Water wet and mixed wet fractured porous media
Spe Reservoir Evaluation & Engineering, 2001Co-Authors: Guo Qing Tang, A FiroozabadiAbstract:Summary A systematic study of the effect of wettability and Initial Water Saturation on Water injection and imbibition is made in Kansas outcrop chalk samples. (Kansas outcrop chalk is very similar to the rock matrix of the North Sea fractured chalk reservoirs.) Waterinjection tests were conducted at different pressure gradients to simulate the effect of gravity (that is, negative P,) on recovery. Based on a large number of carefully conducted tests, the following conclusions are drawn: Initial Water Saturation has a pronounced effect on Water injection in an intermediate-wet chalk. This effect is much less pronounced for a strongly Water-wet chalk. The effects are also in opposite directions. Pressure gradients (which simulate the negative P, effect) have a very strong effect on Water-injection performance in an intermediate-wet chalk. Our interpretation of these experiments leads to the conclusion that recovery from the chalk reservoirs may be nearly independent of wettability state. The results from the experiments also reveal that there is no relation between laboratory measurements of spontaneous imbibition and field performance of mixed-wet reservoirs, even when the wettability state is perfectly restored in the laboratory.
Brent F Thomas - One of the best experts on this subject based on the ideXlab platform.
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formation damage issues impacting the productivity of low permeability low Initial Water Saturation gas producing formations
Journal of Energy Resources Technology-transactions of The Asme, 2005Co-Authors: Brant D Bennion, Brent F ThomasAbstract:Very low in situ permeability gas reservoirs (Kgas<0.1 mD) are very common and represent a major portion of the current exploitation market for unconventional gas production. Many of these reservoirs exist regionally in Canada and the United States and also on a worldwide basis. A considerable fraction of these formations appear to exist in a state of noncapillary equilibrium (abnormally low Initial Water Saturation given the pore geometry and capillary pressure characteristics of the rock). These reservoirs have many unique challenges associated with the drilling and completion practices required in order to obtain economic production rates. Formation damage mechanisms affecting these very low permeability gas reservoirs, with a particular emphasis on relative permeability and capillary pressure effects (phase trapping) will be discussed in this article. Examples of reservoirs prone to these types of problems will be reviewed, and techniques which can be used to minimize the impact of formation damage on the productivity of tight gas reservoirs of this type will be presented.
Ahmed Loukili - One of the best experts on this subject based on the ideXlab platform.
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plastic shrinkage and cracking risk of recycled aggregates concrete
Construction and Building Materials, 2016Co-Authors: Ahmed Z. Bendimerad, Emmanuel Roziere, Ahmed LoukiliAbstract:Abstract This paper presents the results of experimental research on recycled concrete at early age. The influence of recycled gravel and sand (RG and RS) and Initial Water Saturation of RG on plastic shrinkage and cracking sensitivity was investigated. Four Initial Water Saturations were studied: 30%, 70%, 100% and 120% of saturated surface dried (SSD). The total Water was kept constant for all the mixtures, so the added Water was adjusted to take into account the absorption of the aggregates during the mixing process. Other concrete mixtures were designed using 30% and 100% of recycled gravel, and 30% of recycled sand. The gravel/sand ratios were adjusted to keep the maximum paste thickness (MPT) constant. To understand the evolution of early age parameters, a timeline was established and the analyses showed correlations between the evolution of plastic shrinkage and other properties at early age. The Initial Water Saturation did not significantly affect the evolution of plastic shrinkage. Recycled aggregates actually show a relatively high rate of absorption during the first hour after mixing, i.e. before the development of plastic shrinkage. A stress/strength approach based on experimentally assessed parameters was used to compare the cracking sensitivity of different concretes with recycled aggregates. A high rate of substitution of recycled gravel or sand affected the early age properties of the recycled concrete and the cracking sensitivity especially when natural sand was replaced by recycled concrete sand.
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Drying of Recycled Aggregate Concrete: Plastic Shrinkage, Cracking Sensitivity, and Durability
Key Engineering Materials, 2016Co-Authors: Ahmed Z. Bendimerad, Emmanuel Roziere, Ahmed LoukiliAbstract:This paper presents the results of experimental research on recycled concrete at early age and long term. It consists in studying the effect of Initial Water Saturation of recycled concrete gravel (RG). Five mixtures were investigated, one mixture with natural aggregates only (reference concrete) and the second with 100% of RG using four Initial Water Saturations: 30%, 70%, 100% and 120% of saturated surface dried (SSD) state. A stress/strength approach was used to quantify the risk of cracking at early age. It is based on experimentally assessed parameters. At long term the effect of Initial Water Saturation on the ultimate drying shrinkage was investigated. The drying shrinkage was correlated with drying depth and the natural carbonation was also studied. At early age the results indicate RG affected the properties of the recycled concrete. However, the concrete with oversaturated RG showed a behavior close to reference concrete in terms of cracking sensitivity. At long term, the drying shrinkage is weakly depending of Initial Water Saturation, but the durability of concrete can be affected by the drying depth. A good correlation between compressive strength at one day and the carbonation depth at 18 months was observed
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influence of the Initial Water Saturation of aggregates on concrete shrinkage
Mechanics and Physics of Creep Shrinkage and Durability of Concrete: A Tribute to Zdenek P. Bažant, 2013Co-Authors: Emmanuel Roziere, Rachid Cortas, Ahmed Loukili, Ameur El Amine Hamami, Stephanie StaquetAbstract:The study presented in this paper deals with the influence of the Water Saturation of natural aggregates on shrinkage and cracking sensitivity of concrete at early age. Limestone crushed gravels were specially chosen for this study due to their high porosity. The degree of Water Saturation of gravels varied, from a given concrete mixture, keeping the total Water content constant. Significant variations of the plastic shrinkage and early age autogenous deformations were observed. Due to the kinetics of absorption of gravels, the Water content remaining in cement paste was different from the effective Water content. This was confirmed by the values of mechanical properties and porosimetry. The evolutions of elastic modulus and tensile strength were experimentally assessed and used to compare the cracking sensitivity of the three studied concretes by evaluating the self generated stresses.
Brant D Bennion - One of the best experts on this subject based on the ideXlab platform.
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formation damage issues impacting the productivity of low permeability low Initial Water Saturation gas producing formations
Journal of Energy Resources Technology-transactions of The Asme, 2005Co-Authors: Brant D Bennion, Brent F ThomasAbstract:Very low in situ permeability gas reservoirs (Kgas<0.1 mD) are very common and represent a major portion of the current exploitation market for unconventional gas production. Many of these reservoirs exist regionally in Canada and the United States and also on a worldwide basis. A considerable fraction of these formations appear to exist in a state of noncapillary equilibrium (abnormally low Initial Water Saturation given the pore geometry and capillary pressure characteristics of the rock). These reservoirs have many unique challenges associated with the drilling and completion practices required in order to obtain economic production rates. Formation damage mechanisms affecting these very low permeability gas reservoirs, with a particular emphasis on relative permeability and capillary pressure effects (phase trapping) will be discussed in this article. Examples of reservoirs prone to these types of problems will be reviewed, and techniques which can be used to minimize the impact of formation damage on the productivity of tight gas reservoirs of this type will be presented.