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Results
Comparison of Strong-Alkali and Weak-Alkali ASP-Flooding Field Tests in Daqing Oil Field
Guo, Hu (China University of Petroleum, Beijing) | Li, Yiqiang (China University of Petroleum, Beijing) | Wang, Fuyong (China University of Petroleum, Beijing) | Gu, Yuanyuan (China University of Petroleum, Beijing)
Summary Alkali/surfactant/polymer (ASP) flooding is one of the most-promising enhanced-oil-recovery (EOR) technologies. Strong alkali (NaOH) was used in early field tests mainly because of its stronger emulsification ability and wider surfactant range, which can meet the requirements of ultralow interfacial tension (IFT). However, subsequent field tests indicated that the advantages of a strong alkali did not outweigh the disadvantages caused by serious scaling and production-capacity loss. Although a critical comparison of strong alkali ASP (SASP) and weak alkali ASP (WASP) on the basis of field tests is quite difficult and complex, considering the small differences in reservoir characteristics, injected fluid, and operational changes, the two completed field tests in Daqing provided us with valuable and important information. The petrophysical features of the two field tests were similar. The well spacings and well patterns of the two field tests were critically the same, and the same screening standards and design ideas were followed. The incremental recoveries of WASP and SASP were nearly the same, while WASP had a higher peak oil production than SASP after the injection took effect. WASP was proved to have less liquid-producing-capacity loss than SASP. The emulsification effects of WASP were weaker than those of SASP, which also lowered the difficulty and cost of the treatment of the emulsified fluid. The chromatographic separation was different in the two pilot tests, in which WASP had alleviated chromatographic separation. Breakthrough of the polymer occurred before the alkali followed by the surfactant, and this occurred at 0.06 pore volumes (PV) for SASP but was delayed until 0.13 PV for the WASP flooding. The scaling of SASP was much-more severe than that of WASP, leading to a much-higher treatment cost. The economic performances of the two tests, which are of vital importance in a low-oil-price era, were quite different, and WASP had much-better performance than SASP. The input/output ratios of WASP in B-2-X and SASP in B-1-DD were 1:3.7 and 1:2.3, respectively. The returns on investment (ROIs) of WASP in B-2-X and SASP in B-1-DD were 19.1 and 12.9%, respectively, whereas the financial internal rates of return (FIRRs) after tax were 22.3 and 18.0%, respectively. The average FIRR of local oil-industry projects is 12%. Field tests indicated that WASP is both technically and economically better than SASP under the conditions in the Daqing oil field.
- Geology > Mineral (0.69)
- Geology > Rock Type > Sedimentary Rock (0.46)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Mingshui Formation (0.99)
Comparison of Strong Alkali and Weak Alkali ASP Flooding Pilot Tests in Daqing Oilfield
Guo, Hu (China University of Petroleum) | Li, Yiqiang (China University of Petroleum) | Gu, Yuanyuan (China University of Petroleum) | Wang, Fuyong (China University of Petroleum) | Yuliang, Zhang (Research Institute of Xinjiang Oilfield Company, CNPC)
Abstract ASP flooding is one of the most promising EOR technologies. Lots of laboratory studies and pilot tests have been finished in Daqing oilfield which is the largest oilfield in China. Comparison of two typical strong alkali ASP (WASP) and weak alkali ASP (SASP) pilots are presented with detained information. ASP flooding could not only remarkably improve displacement efficiency but also improve sweep efficiency due to the low interfacial tension effect and mobility control technique with help of viscosity enhancement and emulsification effects. The incremental recovery of two ASP was near, while in peak oil production period after the injection took effects, WASP had high oil production rate than SASP. The emulsification effects in weak alkali ASP was weaker than strong one. The chromatographic separation was different in two pilot tests, in which weak alkali ASP had alleviated chromatographic separation. The constitution production sequence was both polymer first, then alkali and finally surfactant. The time gap between surfactant and polymer was about 0.0606 PV for strong alkali ASP, while a respective value of 0.1281PV for weak alkali ASP. Scaling was different and thus anti-scale technique adopted in two pilot tests were a little different. The overall input-output ratio for two tests was different and weak alkali ASP performed much better. Comparison was first made between strong alkali and weak alkali based ASP flooding from field tests perspective. Weak alkali based ASP is proven the development trend.
- North America > United States > California > Sacramento Basin > 3 Formation (0.99)
- Asia > China > Shandong > Bohai Basin > North China Basin > Gudong Field (0.99)
- Asia > China > Shandong > Bohai Basin > Jiyang Basin > Gudong Field (0.99)
- (4 more...)