Flood Testing

In order to determine the flood point, either vapor or liquid flow rate or both are raised. Most commonly, both are raised, because otherwise column material balance is affected and one product will have poor purity before flooding conditions are reached. The following techniques are commonly used for raising vapor and liquid rates during flood testing  

Raising feed rate, while simultaneously increasing reflux and reboil in proportion or in a manner that keeps product composition constant. This technique gives the most direct measurement of the maximum feed rate that can be processed through the column, but can only be applied when upstream and downstream units have sufficient capacity to handle the additional feed. 

Raising reflux and reboil rate while keeping feed rate constant. This is probably the most popular technique used. Only two variables (instead of three) need to be changed, and it is independent of the capacities available in other units, making it simpler and easier to implement. In most cases, data provided by this technique can be easily extrapolated to predict the maximum column feed rate. 

Varying preheater or precooler duty while adjusting reflux and 

Using any of the above techniques, reflux and reboil rates are varied. The procedure of varying these rates is important, and must take the column control system into account. 

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Studies on mechanisms are described by Balzer [192]. In the case of anionics the residual oil in the injection zone is removed via displacement into the adjacent reservoirs ether carboxylates show their good adaptation to differences in temperature and salinity. Further it was found from interfacial tension measurements, adsorption and retention studies, and flooding tests that use of surfactant blends based on ether carboxylates and alkylbenzensulfonates resulted... 

In general, chelating agents possess some unique chemical characteristics. The most significant attribute of these chemicals is the high solubility of the free acids in aqueous solutions. Linear core flood tests were used to study the formation of wormholes. Both hydroxyethylethylene diaminetriacetic acid and hydroxyethyliminodiacetic acid produced wormholes in limestone cores when tested at 150° F. However, the efficiency and capacities differ. Because these chemicals have high solubility in the acidic pH range, it was possible to test acidic (pH less than 3.5) formulations [644]. 

Berea core flood test results (Table VIII) suggested that the presence of DMAEMA improved the permeability damage characteristics of 80% NVP copolymers. The kerosene flow rate... 

Figure 5.7. Flooding test used in experiments of Bailey and Watkins (1951-52) to determine if a L/S system forms stable films (2.a) or drops (2.b).

Table 5.5. Wetting data derived from flooding tests (Bailey and Watkins 1951-52).

Figure 6. Volume of Liquid Between Gas Fingers During Drainage Displacement (GDS Flood) (Test 1-24A)...

The PS micromodel, on the other hand, had fewer pore connections, and the pores were of more uniform size consequently, it was almost completely swept of liquid in the GDS foam flood (Test... 

Surfactant flooding as a technique still has far to go before it be considered a demonstrated aiKl proven technology. Because of the uniqueness of each site and the interaction between surfactant, soil, and contaminant, even pilot-scale studies must be fine-tuned before conclusive results can become available for the development and application of this technique. This paper contributes to the development of this technique by presenting results of column-flooding tests on undisturbed soil cores. 

Table n. Soil Columns and Surfactants Us in Bench-Scale Surf tant Flooding Tests... 

Wang et al. (2001c) performed polymer and ASP flooding tests after the cores were completely watered out. Increasing displacing fluid viscosity leads to a... 

In the Shengtuo commercial polymer flooding test, KAPAM and MO-4000 were injected in two separate areas (Li, 2004a). The test areas are described in Table 5.6, and the water composition is shown in Table 5.7. The formation temperature was 80°C. The injection start dates were as follows ... 

In this test, the viscosity remained higher than 40,000 mPa s after being aged at 90°C for 100 hours. That means the gel solutions were thermally stable by 90°C. Being sheared at 3000 r/min for 15 minutes, the gel solutions lost 87 to 89% of their viscosity. After shearing was stopped, the gel viscosities were restored to 70 to 85% of the unsheared viscosity. Using the reservoir cores of 973 md, the flood tests showed that the plugging rate of 88 to 96% and the residual resistance coefficient of 16.2 to 28.6 were obtained after 10 PV of gel injection. In a three-layered artificial core of 1000 md permeability and 0.72 permeability variation coefficient, the incremental recovery factor of gel treatment was 0.4 to 0.93% OOIP. 

Conduct core flood tests with the polymer solution at different injection rates. Measure the pressure drop, Ap, corresponding to each injection rate (velocity u). The core permeability and porosity are measured before the core flood tests. 

When comparing the viscometric and core flood data, the reader should be reminded that several factors could lead to incorrectly estimated values of Tipp in the core flood tests. The polymer may be adsorbed and retained in the porous media, or there is microgel, which would lead to reduced permeability. Thus, if the permeability reduction is not considered, the estimated Papp using the Darcy eqnation conld be higher than the actual viscosity values because the shear rate is underestimated (see Eq. 5.25). There is also the slip effect (Sorbie, 1991), which occnrs in a low-shear regime and in a low-concentration polymer... 

The difference between Eqs. 7.84 and 7.85 is that the Darcy velocity is used in Eq. 7.84, whereas the pressure gradient and permeability are used in Eq. 7.85. When core flood tests were run at a constant velocity (thus, a constant v a/a), it appeared that the oil recovery increased for those rocks with lower permeabilities (Taber et al., 1973). Clearly, the higher recovery was not a... 

Core flood tests were conducted to compare the performance from the surfactant-polymer option and polymer injection option at different injection schemes. The formula selected for use in the core flood was 0.3 wt.% SLPS -F 0.1 wt.% cosurfactant + 1500 mg/L HPAM. For this formula, the chemical cost was about 2.6/bbl incremental oil. The final selected injection scheme in the pilot is presented in Table 9.4. According to this scheme, the... 

Example 10.2 Scale the Laboratory Core Flood Test in Example 10.1 to a Field Test... 

Suppose we have run a core flood test and confirmed the parameters in Example 1 0.1. Now we want to plan a field pilot. Assume the well spacing is 100 m, and the field injection rate is the same as that used in the core flood test (1 ft/day). Find out the wt.% minimum injection concentration for the pilot. 

Core flood tests were used to compare polymer flood only and alkaline-polymer performance. To model in situ oil/water viscosity ratio correctly, the operator mixed the crude oil with kerosene at a ratio of 100 26. Single-, double-, and triple-column tests were conducted. In the single-column tests, polymer flood increased sweep efficiency over waterflood by 5.6 to 9.77%, and AP flood increased by 13.7 to 19.3%. On average, AP outperformed polymer flood by 8.8%. In the double- and triple-column tests, AP recovery factors were about 18 to 20% higher than waterflood recovery factors. Half of the incremental recovery came from the low permeability column. 

One natural core was used to compare the performance of waterflood (W), AP flood, and ASP flood. The recovery factors for W, AP, and ASP were 50%, 69.7%, and 86.4%, respectively. These core flood tests were history matched, and the history-matched model was extended to a real field model including alkaline consumption and chemical adsorption mechanisms. A layered heterogeneous model was set up by taking into account the pilot geological characteristics. The predicted performance is shown in Table 11.3. In the table, Ca, Cs, and Cp denote alkaline, surfactant, and polymer concentrations, respectively. After the designed PV of chemical slug was injected, water was injected until almost no oil was produced. The total injection PV for each case is shown in the table as well. The cost is the chemical cost per barrel of incremental oil produced. An exchange rate of 7 Chinese yuan per U.S. dollar was used. From... 

Ye and Peng (1995) measured ASP solution/oil relative permeabilities based on the preceding principle. They first conducted a core flood test using an ASP solution and calculated the Darcy viscosity for the solution, which included the polymer permeability reduction factor. Then they conducted ASP/... 

Linear and radial core flood tests were conducted to determine the polymer concentration for mobility control requirement. Figure 13.39 shows Brookfield (UL adapter) viscosity properties for the Alcoflood 1275A polymer in injection water and in an alkaline-surfactant solution. Note that the AS dramatically decreased the viscosity, and a higher polymer concentration was required to provide the same viscosity. 

Salinity was found to decrease foam stability. The surfactant concentrations in which foaming ability increased with concentration were 0 to 0.5%. The optimum polymer molecular weight for foaming ability was around 17 million. Core flood tests showed that ASPF incremental oil recovery factor over ASP was above 10% because the ASPF sweep efficiency was higher than the ASP efficiency. 

Li, H.-E, Liao, G.Z., Han, P.-H., Yang, Z.Y., Wu, X.-L., Chen, G.-Y, Xu, D.-R, Jin, R.Q., 2003. Alkaline/surfactant/polymer (ASR) commercial flooding test in the central Xing2 area of Daqing Oilfield. Paper SPE 84896 presented at the International Improved Oil Recovery Conference in Asia Pacific, Kuala Lumpur, 20-21 October. 

Li, Z.-Q., 2004b. A commercial scale polymer flooding test in Gudao Zhong-1 block of high water cut. Petroleum Exploration and Development 31 (2), 119-121. 

Li, Z.-Q., 2004c. Polymer flooding test progress in Shengtuo block 1 of Shengli Field. Petroleum Processing and Petrochemicals 35 (10), 56—59. 

After a waterflood, the residual oil remaining in the porous reservoir is trapped by capillary forces. The corresponding interfacial tension between the aqueous and the oil phase is of a few mN rrT1 [109, 112-115]. Under these conditions, oil production is marginal and the water cut, on the other hand, becomes high [110, 113, 114]. Addition of surface-active substances (i.e. surfactants), however, can lower the interfacial tension by 3-4 orders of magnitude [109, 112-114, 117, 122, 124], which induces the production of more oil and lowers the water cut [113, 139]. Microemulsion flooding tests both at the laboratory and pilot scales have shown that the oil recovery could be more than 60% of the OOIP [ 110-114], which is about twice the current one. Nevertheless, most of the tests carried out in the field yielded an additional oil recovery of only 10-20% of the OOIP [114, 140], which indicates that the process still has to be improved. 

Figure 5.7-10 has been found to represent flood data for ail crossflow irays. Since the correlation Gist appeared in 1961, a significant number of leige-scale flood tests have been reported, meny of them in the 1,2 m columa of FRI. Analysis has shown that the correlation is conservative,9 and one can use 90% of the predicted flood values as suitable operating levels for design. 

Most of the research on foam sensitivity to oils in porous media, whether in microvisual or core-flood tests, has been concerned with water-wetted pore and throat surfaces. Because petroleum reservoirs are frequently of intermediate, mixed, or oil wettability, it is of considerable interest to understand how rock wettability influences foam stability. 

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