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Introduction All the conducted SAP pilot tests, e.g. Gudong, Karamay. Cambridge Minnelusa, West Kiehl, Sho-Vei-Tun oil fields, have achieved effective results. Crude oil in these oil fields generally bear characteristics of colloid, high paraffin content, high viscosity and high acid value, which is favorable to form ultra-low IFT with SAP solution system, while for non-acidic paraffin oil in Daqing oil field, whose resin and asphaltene content is low and acid value is nearly 0 (>0.3mgKOH/g oil), it is difficult for the crude oil to form ultra-low IFT with SAP solution system. Although successful experience in SAP complex flooding pilot test in Daqing oil field has been achieved, it is necessary to know the interfacial property between non-acidic paraffin and SAP solution, so as to understand the mechanism of SAP complex flooding in this kind of oil field. Our investigation shows that, type and concentration of alkaline play an important role in interfacial property between acidic crude oil and SAP solution system, thus we note complex flooding EOR method in this kind of oil field as ASP combination flooding, while structure, type and concentration of surfactant play a key role in interfacial property between non acidic crude oil and SAP solution system, we note the EOR method in this kind of oil field as SAP combination flooding. Investigation aimed at West Central Saertu SI1-4+5 in Daqing oil field shows that: application of petroleum sulfonate fabricated with fraction of non-acidic crude oil in Daqing oil field SAP combination flooding to enhance oil recovery is effective and economic, it can increase oil recovery rate by about 20% (OOIP). Field History and Condition Pilot area is located in western part of central Saertu, Daqing oil field, target layer is SI1-4+5. polymer flooding pilot test was conducted in P1-4 oil formation of this area in 1990-1992, then later move to the upper SII1-3 oil formation, SAP complex flooding pilot test was conducted in 1993-1995, then later move to upper SI1-4+5 oil formation to pre-perform this SAP complex flooding pilot test. The pilot area is composed of 4 inverse 5 spot well patterns, with 4 injectors, 9 producers, 1 inspection and 1 coring well respectively, average injector-producer well space is 106m, and production well space is 150m. Area of pilot area is 0.09km2, with average effective thickness of 5.15m, effective permeability of 0.3um2, permeability variation factor of 0.6653, pore volume of 10.47×104m3, and geological reserve of 6.92×104t; area of central well block is 0.0154km2, with effective thickness of 6.1m, pore volume of 2.2×104m3, and geological reserve of 1.45×104t. Reservoir parameter of pilot area is shown in table.1 Family composition of Daqing crude oil is shown in table 2-3 Waterflooding of the Pilot Area SI oil group of pilot area was put in to injection in Dec, 1996 to perform blank test, injectivity index is 2.36m3/d.m.Mpa, injection intensity is 2.08m3/m.d, original oil saturation of this formation is 79.4%, original oil saturation contour diagram of SI4+5 is shown in fig.2, test shows that, total non-water flooded thickness accounts for 81.9% of whole thickness, current residual oil saturation is 69.7%, current recovery percent is 12.14%(OOIP), water wash performance of each layer is shown in table.4. Investigation on formulation of SAP system For the speciality of non-acidic paraffine crude oil, surfactant is considered preferentially in the screening of formulation of SAP system, screening principles are: 1.the system can form ultra-low IFT (1~10-3mN/m) with petroleum in a wide range; 2. good compatibility with reservoir and other additives; 3. high oil displacing efficiency; 4. the products can be produced and applied in Daqing. Field History and Condition Pilot area is located in western part of central Saertu, Daqing oil field, target layer is SI1-4+5. polymer flooding pilot test was conducted in P1-4 oil formation of this area in 1990-1992, then later move to the upper SII1-3 oil formation, SAP complex flooding pilot test was conducted in 1993–1995, then later move to upper SI1-4+5 oil formation to pre-perform this SAP complex flooding pilot test. The pilot area is composed of 4 inverse 5 spot well patterns, with 4 injectors, 9 producers, 1 inspection and 1 coring well respectively, average injector-producer well space is 106m, and production well space is 150m. Area of pilot area is 0.09km2, with average effective thickness of 5.15m, effective permeability of 0.3um2, permeability variation factor of 0.6653, pore volume of 10.47×104m3, and geological reserve of 6.92×104t; area of central well block is 0.0154km2, with effective thickness of 6.1m, pore volume of 2.2×104m3, and geological reserve of 1.45×104t. Reservoir parameter of pilot area is shown in table.1 Family composition of Daqing crude oil is shown in table 2-3 Waterflooding of the Pilot Area SI oil group of pilot area was put in to injection in Dec, 1996 to perform blank test, injectivity index is 2.36m3/d.m.Mpa, injection intensity is 2.08m3/m.d, original oil saturation of this formation is 79.4%, original oil saturation contour diagram of SI4+5 is shown in fig.2, test shows that, total non-water flooded thickness accounts for 81.9% of whole thickness, current residual oil saturation is 69.7%, current recovery percent is 12.14%(OOIP), water wash performance of each layer is shown in table.4. |
