Reservoir sand consumption

Lieu, V.T., Miller, S.G., Staphanos, S.J., 1982. Long-term consumption of caustic and silicate solutions by petroleum reservoir sands. Soluble Silicates, Am. Chem. Soc. Symposium Series 194, 215-226. 

The coking of reservoir sands in the bottomhole zone must take place under strictly controlled conditions as regards (a) the rate of air injection (b) rate at which the temperature of injected air is increased (c) the temperature maximum (d) the duration of the treatment, and (e) the energy consumption. 

Long-Term Consumption of Caustic and Silicate Solutions by Petroleum Reservoir Sands... 

A number of laboratory investigations were made into different aspects of consumption of sodium hydroxide and sodium orthosilicate in alkaline flooding of petroleum reservoirs for enhanced oil recovery. One investigation studied the role of reversible adsorption and of chemical reaction v en petroleum reservoir sands are contacted with alkaline solutiais. Another investigation studied the effect of flow rate on caustic consumption by means of a series of flow experiments through reservoir sand packs. A third series of high rate flow experiments studied changing alkaline consumption with time. 

The coisurr tion of alkaline chenical in tJie reservoir is a function of the amount and type of rock minerals r surface area and of the sands compactnessr alkaline chemical concentration used, reservoir temperature and the time the alkaline chemical is exposed to the reservoir sand (1, 4, 11) These factors are interdependent and together determine the overall consumption. 

As can be seen from Figure 1, where sodium hydroxide consumption is plotted as a function of time the consumption of caustic by all three sands was rapid as much as 35 to 60 meq /lOOg sand were consumed after 62 days. The consumption reactions were still in progress v en the experiments were terminated. From this study, it became obvious that caustic consumption by reservoir sand can be a long term phenomenon. 

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...

This section describes our study of the extent of reversible adsorption (and/or ion exchange) as compared with non reversible chonical consurtption between alkaline chemicals and reservoir sands. This is significant because in the case of reversible adsorption, the loss of alkaline chonical is temporary and thus the alkalinity may be recovered on the other hand, chenv-ical consumption is permanent and cannot be recovered. 

Figure 5. is a plot of % NaOH consumed versus the flow rate. It can be seen that the % NaOH ccxisumed increases with reduction in flow rate. Hiis is to be expected since with the slower flow rate, longer time is available for the caustic solution to react with the reservoir sand. Hiat is, slower flow rates increase the reaction residence time. For example, 1/3 PV/day correspovas to a residence time of 3 days, allowing longer exposure between the caustic and reservoir sand, and hence, more consumption. 

Campbell (13) measured rock consumption by stirring unconsolidated reservoir sand with 0.5% sodiun hydroxide or 0.5% sodium orthosilicate and the alkaline consumptiais were found to be about the same for the two solutions. The difference in the conclusions between our study and that of Campbell is not understood and is presently being studied. It seons to be be related to the difference in methods used ("Jar" test vs. 

Lieu, V. T., Miller, S. G., and Staphonos, S. J., "Long-term Consumption of Caustic and Silicate Solutions by Petroleum Reservoir Sands," in Soluble Silicates, American Chemical Society Symposium Series, No. 194, pp. 215-226,1982. 

The gas reservoirs located ia very deep waters, ia coal beds, and ia tight sands are now more accessible. Fifteen percent of the U.S. gas supply ia 1992 was derived from tight sand formations and 1.4 x 10 of coal-bed methane was added to the proven reserves (22). In 1992, U.S. proven reserves were placed at 4.67 x 10 ia the lower 48 states, and it was estimated that the identified gas resource ia the United States and Canada exceeds 3.4 X 10. Based on the 1992 rate of natural gas consumption, the United States has between 8 and 10 years of proven reserves and a domestic... 

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