Sandstone reservoir self-diverting acidizing method

Abstract

The invention discloses a sandstone reservoir self-diverting acidizing method, which comprises the following steps of (1) injecting diverting acid into a sandstone reservoir to be used as ahead liquid; (2) injecting processing liquid into the sandstone reservoir; (3) injecting subsequent liquid into the sandstone reservoir; and (4) injecting displacing liquid into a pit shaft, and jacking acid liquid in the pit shaft into the deep path of the reservoir. The diverting acid is prepared from the following ingredients including 12 to 15 percent of HCl, 3 to 10 percent of diverting agents, 4 to 8 percent of additives and the balance water, wherein the diverting agents are erucyl amide hydroxysulfobetaine; the processing liquid is various kinds of conventional processing liquid suitable for sandstone acidizing; the subsequent liquid is prepared from the following ingredients including 5 to 15 percent of HCl, 1 to 2 percent of gel breakers, 4 to 8 percent of additives and the balance water; the displacing liquid is diesel oil, gasoline or 3-percent ammonium chloride solution. The percentage of the ingredients is mass percentage. The sandstone reservoir self-diverting acidizing method has the advantages that the uniform acid distribution effect of the acid liquid in the reservoir can be improved; the subsequent gel breaking residue is reduced; and the inhomogenous reservoir acidification is realized.

Description

technical field [0001] The invention relates to a method for improving the acidification effect of heterogeneous sandstone reservoirs in the process of matrix acidification in the field of oil and gas field development, in particular to a method for self-steering and split flow acidification of sandstone reservoirs. Background technique [0002] For sandstone reservoirs, there are mainly three conventional acidizing and diverting technologies: one is to use packer tools to selectively divert and acidify wells with large intervals between layers or perforation intervals, so that most of the wells with vertical heterogeneity The reservoir has been effectively improved, but at the same time there are great limitations. On the one hand, due to the strong heterogeneity of the formation during the conventional acidizing process, the acid liquid is likely to "finger" in the large pores and fractures of the high-permeability layer, which cannot make the low-permeability layer On the...

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Problems solved by technology

[0002] For sandstone reservoirs, there are mainly three conventional acidizing and diverting technologies: one is to use packer tools to selectively divert and acidify wells with large intervals between layers or perforation intervals, so that most of the wells with vertical heterogeneity The reservoir has been effectively improved, but at the same time there are great limitations. On the one hand, due to the strong heterogeneity of the formation during the conventional acidizing process, the acid liquid is likely to "finger" in the large pores and fractures of the high-permeability layer, which cannot make the low-permeability layer On the other hand, for wells with small distances between layers or perforation sections, it is impossible to use tools to pack and acidify wells. Third, the process of lifting and unloading packers is cumbersome and the construction cost is high.

The second is to use granular temporary plugging and diverting agents for diversion acidification, mainly including sodium benzoate and phenolic resin, but these two types of chemical substances also have limitations during construction. To achieve the ideal temporary plugging and diversion effect, at the same time, as soon as the solid phase particles enter the wellbore during the construction process, solid phase cakes will form on the well wall and cannot enter the high-permeability pores to achieve the ideal temporary plugging and diversion effect

The third is to use viscosity-increasing diverting agents for diversion acidification, mainly including polymer viscosifiers and viscoelastic surfactants. These two types of chemical substances are currently mainly used for acidizing and fracturing in carbonate rock reservoirs, and the reduction has been achieved. The role of filtration, these two types of sandstone reservoirs have their own shortcomings, polymer residues are serious, and viscoelastic surfactants also have their own shortcomings in the process of turning sandstone reservoirs, because sandstone reservoirs The content of hydrochloric acid solubles is low, and in order to reduce the secondary damage caused by the treatment liquid to the reservoir during the construction process, it is necessary to maintain a high concentration of H during the entire construction process. + Therefore, if the viscoelastic surfactant is directly used as the diverting agent for sandstone acidification, it is easy to cause the acid liquid to break the gel and make it difficult to flow back the acid liquid during the acidification process.

[0003] In order to solve the problem that the existing split-flow acidizing technology for heterogeneous sandstone reservoirs in the oil field is insufficient, which makes the acidizing effect of heterogeneous sandstone reservoirs in long well sections poor, research new acidizing technologies suitable for the actual situation of acidizing sandstone reservoirs , it is urgent

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