Heavy oil displacement method using wedged vicious slug

Abstract

The invention relates to a heavy oil displacement method using a wedged vicious slug. The method includes the steps of 1, dividing a nonhomogeneous reservoir into a plurality of layers according to water absorbing capacities, and acquiring permeability Ki of each reservoir; 2, designing three slugs, namely a pre-slug, a main wedged slug and a trailed slug, according to the permeabilities Ki and the physical properties in heavy oil and reservoirs; 3, alternately injecting the heavy oil reservoir with the pre-slug which is prepared with low-concentration B III-type poly-surfactant and which enters a high permeability layer to emulsify crude oil; 4, injecting the reservoirs with the main wedged slug for multiple rounds; and 5, injecting the trailed slug with low-concentration B III-type poly-surfactant or fresh water generally. In each round, the main wedged slug is divided into three small slugs; the small slugs in each round are combined by regulating the corresponding concentrations by the B III-type poly-surfactant according to formation permeability. According to the method, the nonhomogeneous heavy oil reservoirs are emulsified to reduce viscosity, the wedged equivalent vicious slug is used for equi-fluidity displacement, and swept volume is increased; accordingly, recovery efficiency of heavy oil can be further increased, investment can be reduced and operation can be simplified.

Description

Technical field: [0001] The invention relates to an oil displacement method for a heterogeneous heavy oil reservoir in the field of petroleum exploitation, in particular to a wedge-shaped viscosity slug oil displacement method for heavy oil. Background technique: [0002] With the continuous exploitation of oil, the oil reserves in the world, especially high-quality and easy-to-recover oil reserves, are constantly decreasing. In the proven oil resources, the proportion of heavy oil is increasing. my country is rich in heavy oil resources, and there are heavy oil reservoirs distributed in Liaohe, Xinjiang Karamay, Shengli, Henan, North China, Daqing and other oil fields. [0003] Due to its high viscosity, heavy oil is difficult to be recovered by ordinary methods. Because the viscosity of heavy oil is very sensitive to temperature, the main method of recovering heavy oil is thermal oil recovery, such as steam huff and puff and steam flooding. Steam stimulation and steam fl...

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Problems solved by technology

In the method of heavy oil recovery by steam huff and puff, huff and puff can only recover the crude oil in the formation near the wellbore of the oil well, but there is still a large amount of heavy oil between the wells that has not been recovered, and the recovery rate is only 10% to 20%. After steam flooding, part of the crude oil in the interwell formation can be recovered from the ground, and the recovery rate of heavy oil can be further increased by 20% to 30%. However, this method consumes a lot of heat energy, requires a large investment, is complicated in technology, and has high risks. , the current production of steam flooding is smaller than that of steam stimulation

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