Refracturing method for digging remaining oil of crack in side direction in extremely-low permeability reservoir old well

Abstract

The invention discloses a refracturing method for digging remaining oil of a crack in the side direction in an extremely-low permeability reservoir old well. The method comprises the following steps that (1) a lateral production well in the water driving predominant direction is selected, and a potential layer section is preferably selected; (2) oriented perforating is conducted on the potential layer section and the distribution direction of remaining oil; (3) a dual-sealing fracturing string is tripped in a newly perforated layer section; (4), a layer section subjected to oriented perforating is subjected to continuous construction of acid fracturing and refracturing; (5), well shut-in and open flowing are conducted, the fracturing string is pulled out for repeated production. Accordingto the method, new turning cracks are formed in the refracturing process of an extremely-low permeability reservoir old oil field, remaining oil in the side direction of old cracks is dug, and the purposes of controlling water and increasing oil are achieved.

Description

technical field [0001] The invention relates to the field of oil production engineering, in particular to a method for increasing production by repeated fracturing for tapping the remaining oil potential in the lateral direction of fractures in an old well in an ultra-low permeability oil reservoir. Background technique [0002] The ultra-low permeability sandstone reservoir represented by the Chang 6 layer of Ansai Oilfield has a large thickness (15-20m) in the vertical direction and multiple small layers in the layer. The main development method is "water injection + fracturing" For development, the degree of initial shot opening is low (30%-40%). Affected by reservoir heterogeneity and fracture extension after multiple rounds of measures, with the prolongation of production time, the oil wells with fractures in the main direction have the dominant direction of water flooding, resulting in premature water breakthrough in the main direction oil wells. At the same time, the...

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Problems solved by technology

[0003] The above-mentioned existing lateral residual oil tapping methods mainly have the following problems: First, the construction controllability of a single temporary plugging agent in fractures is poor, the effect of temporary plugging and boosting pressure and construction continuity are not ideal, the success rate is low, and lateral fracture creation is difficult ; Second, the use of dense well layout has a greater impact on the production decline of old wells (from the second year onwards, an increase of more than 8% decline), and the single well productivity of new wells is low; High, slim hole production and maintenance are difficult

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