| Since the implementation of SP flooding on block J16, due to the impact of heterogeneity, part of the injection wells single suction is too large, moving speed of liquid in each layer is not uniform, the concentration of polymer in production wells increases rapidly. So we need to make the investigation on SP flooding injection method using Multi-slug with equi-mobility, by improving local closure pressure gradient in high permeability channels, to solve this kind of contradiction.A series of flooding experiments have been carried out to make the equi-mobility slug design. The experimental results show that: the mobility and viscosity of SP solution has a power function relationship in the same permeability.Investigation has been made to characterize the mobility control ability of the designed slugs. The experimental results show that: under the commingled water injection condition, single molecular weight is better than continuous reduction of molecular weight on fractional flow rate control. Under the single-string multi-zone injection condition, continuous reduction of molecular weight can achieve an ideal effect, which increased the recovery by 19.11% OOIP compared to the commingled water injection, more important the main contribution is made by the low permeability layer.A series of flooding experiments have been conducted to observe the additional oil recovery of SP flooding injection method using Multi-slug with equi-mobility. The experimental results show that: Under the condition of single molecular weight(2500×104),three equi-mobility slugs increased the recovery by 4.45% compared to the single slug. Four round injection(continuous reduction of molecular weight) showed the best oil displacement effect, the additional recovery is 35.2% OOPI, increased the recovery by 13.92% compared to the single slug. The four round injection can better control the rising speed of water, a long time to maintain the high injection pressure, maximum enhancing oil displacement effect. |
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