Berea sand

Figure 9 Adsorption (rag/g) dependence of nonionic cellulose ethers (2500 ppm) on salinity (N, NaCl) of aqueous solution. Substrate Berea sand (85 wt.%) blended with montraorillonite (15 wt.%). W-SP symbols ...

Berea sand Quartz + 1 0-1 5% clay 75-80% kaolinite 15-20% illite 30-56 47... 

THE EFFECT OF MICROEMULSION COMPOSITION ON THE ADSORPTION OF PETROLEUM SULFONATES ON BEREA SAND/MONTMORILLONITE CLAY ADSORBENTS... 

The adsorption from microemulsion of two petroleum sulfonates, PDM-334 and TRS 10-410, on Berea sand/montmorillonite clay adsorbents has been studied to determine 1) the effect of microemulsion composition, specifically its relative oil and brine content, on sulfonate adsorption 2) the effect of adsorption on the microemulsion composition and interfacial tension behavior. Whereas the degree of sulfonate adsorption can be determined by conventional methods (e.g. UV spectroscopy), one must utilize a microemulsion property which is a sensitive function of the relative oil and brine content of the microemulsion in order to determine the adsorption-induced changes in the microemulsion composition. This can be accomplished by the use of the microemulsion specific refraction. 

The Berea sand was obtained from Cleveland Quarries in Amherst, Ohio the montmorillonite was a clay mineral standard from Ward s Natural Science Establishment, Inc. Both solids were characterized well in terms of particle size distribution and surface area. The crushed clay and sand were sieved separately using US sieve series the fractions of sand and clay which passed through sieve No. 170 but not No. 200 were retained for use as adsorbents. The particle size distribution of these fractions is fairly narrow with the majority of particles in the 74-88 ym range (10). The surface areas of these adsorbents as determined by nitrogen adsorption were 2.86 m /g for the sand and 84.7 m 2/g for the clay. 

A known volume of microemulsion was then added to a bottle containing weighed amounts of the Berea sand and montmorillonite clay the bottle was sealed, placed on a roller and rotated gently at constant temperature for 48 hours. 

Fig. 3.5. Mechanical stability of HRAM and PAM as measured by flow through a Berea sand-stone core at flow rates of 10-10 ml/h...

The core experiments with Kern River oil were performed using sandpacks (25.4 cm by 3.7 cm) made from unconsolidated field core. The core material was packed into Teflon sleeves with Teflon end caps and then placed into a Hassler type core holder. Before packing, the sand was cleaned by Soxhlet extraction with toluene and was not fired. Otherwise, the procedure was similar to that for saturating the consolidated Berea sandstone cores. 

Martin (1959) and Bernard (1967) observed that clay swelling and/or dispersion accompanied by increased pressure drop resulted in incremental oil recovery. Tang and Morrow (1999) concluded that line mobilization (mainly kaolinite) increased recovery based on their observations (1) fired/acidized Berea core showed insensitivity of salinity on oil recovery, whereas unlired Berea core did show sensitivity and (2) for clean sandstones, the increase in oil recovery with the decrease in salinity was less than that for the clay sands. Figure 3.4 shows some of their results. In the tests, the reservoir CS core was used. The reservoir brine, CS RB, was used as connate brine for the entire CS core tests. 

The sample identifications are as follows 1) Berea sandstone, Amherst, Lorain County, OH, 2) Glenn Sand, Glenn Pool Field,... 

Figure 1. Electron micrographs of Berea sandstone and selected core samples (a) Berea sandstone, representative fracture surface, 102.75X (h) Berea sandstone, clay on quartz crystals, 959X (c) Glenn sand core, representative fracture surface, 123.3X (d) Glenn sand core, clay crystals on quartz, 3938.75X (e) San Andres core, representative fracture surface, 123.3X (f) San Andres core, clay and dolomite crystals, 993.25 X.

Energy dispersive X-ray analysis (EDXA) is of assistance in identifying the principal chemical elements in particular crystals. This information, along with crystal shape, enables one to identify reasonably well the minerals likely to be contacted by a surfactant slug when injected into a core or a reservoir formation. Thus, the basic sand matrix of these materials is revealed while the presence of particular clay minerals, such as kaolinite, can be seen in Berea sandstone and Glenn Sand dolomite appears to be present in significant amounts in the core from the San Andres formation. 

Adsorption on Berea Sandstone. Berea sandstone was reported by Malmberg and Smith (20) to consist of approximately 91 wt.% sand and 9 wt. % clay. The adsorption measurements reported here are for the crushed sandstone but it should be noted that essentially all of the adsorption occurred on the clay fraction. In a separate experiment the clay fraction was separated from the sand and the adsorption of SDBS measured on both fractions. No adsorption on the sand could be detected while strong adsorption on the clay was found. Moreover, the adsorption on the clay agreed very well with that found on the original crushed sandstone when converted to a common basis. 

Figure 11. The dependence of surfactant adsorption on temperature, measured in Berea sandstone or silica sand. Adsorption levels were obtained using the surface excess model (1—10).

Clays are considered detrimental to EOR processes that are based on the injection of chemicals, such as foam-forming surfactants, because clays provide a large amount of surface area for adsorption. Table VII shows a comparison of specific surface areas of some clays (97, 117, 118) and of the solids used in the adsorption experiments of Figure 15 (12, 119, 120). Figure 15 allows comparison of adsorption levels in Berea sandstone, which consists mainly of quartz and 6-8% clays, with adsorption on clean quartz sand. 

When normalized to unit surface area, the adsorption density of the anionic surfactant is higher on quartz than on Berea sandstone because quartz carries a more positive surface charge than the clays (The clays provide most of the surface area for adsorption in Berea sandstone). If it is assumed that the betaine adsorbs on sandstone at least in part by its cationic group, then the lower adsorption density of the betaine on quartz than on Berea sandstone can also be attributed to electrostatic interactions. Matrix grains of the size encountered in typical reservoir rocks have low specific surface areas. Accordingly, the absolute amount of surfactant adsorbed or the amount adsorbed per unit mass of rock is lower for a clean sand than for a sand containing clays (12, 34, 82). Therefore, the... 

Figure L Static equilibrium experiments to study caustic consumption of reservoir sands in the presence of large excess of NaOH solution. Key A, Aminoil LMZ sand at 165°F in 0.2% NaOH O, THUMS Ranger sand at 125°F in 0.2% NaOH X> Berea sandstone sand at 125°F...

In another set of static equilibrium tests, one pore volime (PV) of alkaline solution was mixed individually with Aminoil IMZ, THUMS Ranger and Berea sandstone sands. The volume of one PV used was calculated from the porosity of the same sand v en it was packed for sand pack flow study. After standing for a number of days, the mixtures were filtered and the filtrates were analyzed for their alkaline consurtption by titration with standard acid. As depicted in Table II, the consurapticxis were rapid in all cases and the alkaline chemicals were totally or almost totally consumed after 6 to 9 days for the THUMS Ranger and Aminoil IMZ sands. The consumption with Berea sandstone sand was slower by comparison but still quite significant. 

STATIC EQUILIBRIUM STUDY TO DETERMINE THE RELATIVE REACTIVITY OF RESERVOIR SANDS AND BEREA SANDSTONE SAND WITH THE USE OF Cm PORE VOLUME ALKALINE CHEMICALS AT 125 F... 

Aminoil IMZ Sand 100% (after 6 days) TOUMS Ranger Sand 100% (after 6 days) Berea Sandstcxie Sand... 

The oil displacement studies are the final step in the screening procedure. They are usually conducted in two or more types of porous media. Often initial screening experiments are conducted in unconsolidated sand packs and then in Berea sandstone. The last step in the sequence is to conduct the oil displacement experiments in actual cored samples of reservoir rock. Frequently, actual core samples are placed end to end in order to obtain a core of reasonable length since the individual eore samples are typically only 5-7 in long. 

Sand, used as a porous medium, was supplied by AGS CO Corp., Paterson, New Jersey, U.S.A., whereas the Berea sandstones were supplied by Cleveland Quarry, Cleveland, OH, U.S.A.. The size distribution for the sand used was 40-150 micron with average particle size of 95 micron. The sandstone cores were cast in Hysol Tooling Compound (Hi-Co Associates, Orlando, FL) inside PVC pipes. The sandpacks had permeabilities of about 2.5 darcy and porosities of 40%, whereas Berea sandstones had permeabilities of about 275 millidarcy cind porosities of 18%. The transducer used for the measurements of pressure across the porous medium was from Validyne Engineering Corp., Northrddge, CA, U.S.A.. The recorder was a Heath/Schlumberger Model 225, Heath Co., Benton Harbor, MI, U.S.A.. The water was pumped using a Cheminert metering pump Model EMP-2, Laboratory Data Control, Riviera Beach, FL, U.S.A.. 

Holbrook and Bernard (3) showed that Berea sandstone cores and 250-mesh sand adsorbed about 0.4-0.7 mg dye/gm core and 0.45 mg dye/ gm core, respectively, of methylene blue from 0.01 percent dye solutions, whereas the amount of adsorption was nil when the cores, or the sand, were treated with 5 percent Dri-Film SC-87 solution in hexane, oven dried and saturated with Soltrol. One of the untreated sandstone samples which was first saturated with water, driven to irreducible water with oil and then flooded to residual oil saturation with the dye solution adsorbed the same amount of dye as the untreated sample not containing oil, thereby indicating that in the process of water-flooding a water-wet core, the entire pore surface is contacted by the flood water. 

Oil displacement in porous media Horizontally mounted sand-packs and Berea cores encased in an air-circulating constant temperature box were used for oil displacement efficiency tests. 

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