Commercial ASP Flood Test in Daqing Oil Field

Abstract

Alkali-Surfactant-Polymer (ASP) pilot test with small well spacing and the test with enlarged well spacing for commercial ASP flood are successful in Daqing Oil Field, demonstrating ASP process can greatly enhance oil recovery and bring more economic benefits. However, there are also some problems appearing during ASP flood test, such as serious scale, produced fluids hard to be disposed, and with the well spacing enlarged these two disadvantages might be worse. Therefore, a commercial ASP field test is performed to study performances of ASP flood, scaling characteristics and processing techniques of produced fluids. The five-spot well pattern is adopted in test area, including 18 injection wells and 29 producing wells, and chemical agent, sodium alkylbenzene sulfonate, is produced by Daqing Oil Field. On the basis of laboratory core flood, the formula has been optimized, which can create ultra-low interfacial tension with wide ranges and favorable emulsification. The studies, laboratory core test and numerical simulation, show that ASP system can improve oil recovery 20% more than water injection. At present, polymer injection is following the ASP flood, and the performances from commercial ASP flood are different from those of previous ASP flood. When water cut is slight declined, the injectivity will be greatly increased; the scale is serious for ground equipment, but it is rarely found in the borehole. With the surfactant produced, oil and water separation of produced fluid becomes much harder. The oil recovery enhanced by commercial ASP flood is less than ASP pilot test. If the well spacing is shortened, surfactant performance further improved and ASP system is more optimized, oil recovery efficiency will be further enhanced.

Evaluation of the Factors Influencing Residual Oil Evolution after Alkali/Surfactant/Polymer Flooding in Daqing Oilfield

“…After ASP flooding using the new formula, the residual oil types were like those after using the oil formula, but the proportion of the residual oil in droplet form was larger than that in cluster form. As shown in Figure 14, for the sulfonate system, because of the insufficient emulsifying ability, most of the residual oil in clusters was larger than 1000 voxel 3 . The emulsifying ability of the new formula was significantly better than that of the sulfonate system.…”

“…Daqing Oilfield is experiencing an ultrahigh water cut, and now is the first oilfield in the world that has implemented field-scale chemical flooding projects [1][2][3]. The ordinary tertiary displacement method (polymer-only or surfactant-only flooding) cannot provide sufficient improvement in oil recovery.…”

Chemical enhanced oil recovery and the role of chemical product design

“…Several smaller ASP oilfield applications are also studied in the literature [63,70,450,[465][466][467][468][469][470]. In Daqing the pilot tests reported oil recoveries were increased by 21 to 24 % OOIP using ASP flooding over waterflooding [471][472][473][474][475][476][477][478]. In the recent years, a significant progress has been made in both laboratory studies and pilot tests to show the potential of ASP projects in mature oilfields [322,454,460,469,472,[479][480][481][482][483][484][485][486].…”

A comprehensive review of emulsion and its field application for enhanced oil recovery

“…There are very few field test cases of emulsion flooding, and the most successful case is the field test at Section 5K of the Midway‐Sunset Oil Field . However, an obvious emulsification phenomenon appeared in the ASP flooding field test, which resulted in the development of reference values for laboratory studies and field tests of emulsion flooding.…”