Multi-slug composite pressure decreasing and injection increasing agent for ultra-low permeability oil field

Abstract

The invention relates to a multi-slug composite pressure decreasing and injection increasing agent for an ultra-low permeability oil field and belongs to the technical field of chemical pressure decreasing and injection increasing of the ultra-low permeability oil field. According to the agent, active retarded acid, a complex antiscaling agent, a shrinking agent and an antisludging agent are integrated, and a multi-slug and staging injection mode is adopted, so that the plugging of the formation of a water injection well of the ultra-low permeability oil field is effectively eliminated, the injection allocation of an under injection well is realized, and the water injection pressure of the under injection well is reduced, the energy of the formation is supplemented, and the recovery efficiency of crude oil is improved. The problem of low acidification effect and short effective period of measures, which are caused by shortened penetrating distance, the problem that the effects of an active agent are reduced because the active agent cannot reach a far well zone, and the problems of reduced permeability, shortened effective period, ineffectiveness or increased water injection pressure, which are caused by incompatibility of formation fluid and new generated precipitates in the process of applying the conventional single pressure decreasing and injection increasing technology to the ultra-low permeability oil field at site can be solved. The results of a site test prove that the effective rate of the measures can reach 91.3 percent, and the pressure of a single well can be decreased by 1.5MPa averagely.

Description

technical field [0001] The invention relates to a multi-slug composite depressurization and injection booster for ultra-low permeability oilfields, which belongs to the technical field of chemical depressurization and booster injection for ultra-low permeability oilfields. Background technique [0002] High water injection pressure has become an important factor restricting water injection development in low permeability oilfields, which not only causes reservoir damage, but also affects the improvement of ultimate oil recovery. However, increasing pressure and increasing injection is not a long-term solution for waterflooding development of low permeability oilfields. Only by controlling the rising trend of water injection pressure and doing a good job in injection water reformation and depressurization and increasing injection can the waterflooding development of low permeability oilfields have a way out. [0003] At present, the chemical depressurization and augmentation ...

AI Technical Summary

Problems solved by technology

However, ultra-low permeability oilfields (meaning the permeability is lower than 1×10 -3 μm 2 The salient features of water injection development are high displacement pressure, small effective driving pressure difference between oil and water wells, poor benefit of oil wells, and many low-yield and low-efficiency wells

[0004] Practice has proved that in the field application of the traditional and single depressurization and injection technology in ultra-low permeability oilfields, either because the acid rock reaction speed is too fast and the penetration distance is short, resulting in poor acidizing effect and short effective period of the measures; Surfactants have a large amount of adsorption near the well, so that they cannot reach the far well zone, reducing the effect of the active agent; or the injected chemical agent is incompatible with the formation fluid, and new precipitation occurs, resulting in a decrease in permeability. Decrease; resulting in low success rate of measures, short validity period, or even invalid or water injection pressure does not drop but rises