A method for diverting and diverting acidification of long well sections in high-permeability sandstone reservoirs

Abstract

The invention relates to a high-permeability sandstone reservoir long well section diversion diversion acidification method, comprising: 1) using well-washing fluid A agent to perform circular cleaning from the oil casing annulus; 2) replacing the well-washing fluid in the drained wellbore with clean water ;3) Inject profile control agent B agent into the formation, B agent is composed of the following components by weight percentage: 0.5-5% polysaccharide + 0.1-2% regulator + 0.05-0.2 corrosion inhibitor + 0.5-2% clay stabilization 4) Inject phase change plugging agent C agent into the formation, C agent is composed of the following components by weight percentage: 20‑50% solid phase former+1‑5% surfactant+0‑30% Regulator + 0.5-2% clay stabilizer + 0-2% corrosion inhibitor, and the rest is water; 5) inject plugging agent D into the formation, and D agent is composed of the following components by weight percentage: inorganic plugging agent 5 ‑30% + penetration aid 5‑20% + system stabilizer 1‑2%, and the rest is water; 6) Inject displacement fluid E agent into the wellbore; 7) After shutting down the well for 30‑120 minutes, open the well and drain the fluid. The invention can improve the uniform acid distribution effect of the acid liquid in the reservoir, and realize matrix acidification of the long well section and high-permeability heterogeneous reservoir.

Description

technical field [0001] The invention relates to a method for improving the effect of general acidification of high-permeability heterogeneous sandstone reservoirs in the process of matrix acidification in the field of oil and gas field development, in particular to a method for acidizing high-permeability sandstone reservoirs with long well section diversion diversion. Background technique [0002] The homogeneity of oil and gas reservoirs is relative, while the heterogeneity is absolute. Due to the heterogeneity of the reservoir, if the conventional acidification process is used to acidify the reservoir, the acid liquid will form a "fingering" phenomenon in the large pores and fractures of the high-permeability layer, which cannot make the low-permeability layer and small pores be effectively reformed. In order to improve the acidizing effect, the most commonly used measure is to introduce the method of temporary blocking and diversion in the construction procedure. [00...

AI Technical Summary

Problems solved by technology

[0003] 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, and it is difficult to achieve intra-layer, Intra-fracture diversion, on the other hand, it is not possible to use tools to pack and acidize wells with small distances between layers or perforation intervals, and on the other hand, the process of lifting and unloading the packer 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 the construction process, as soon as the solid particles enter the wellbore, they will form a solid phase on the wellbore wall The cake is packed and cannot enter the high-permeability pores to achieve the ideal temporary plugging and diversion effect. At the same time, the solid-phase particles are likely to cause damage to the equipment and the electric submersible pump during the injection and flowback process.

These two types of chemicals are mainly used in acidizing and fracturing of carbonate rock reservoirs to reduce fluid loss. If they are used in sandstone reservoirs, they have their own shortcomings, such as: polymer residues are serious, and during the acidizing process Viscoelastic surfactants have harsh gelation conditions and are difficult to break. At the same time, surfactants are small molecules. Therefore, gelation with a certain strength requires a high concentration, which eventually leads to high costs and difficult flowback.

[0004] In order to solve the shortage of current split acidizing technology for heterogeneous sandstone reservoirs in the oil field and improve the poor acidizing effect of high-permeability heterogeneous sandstone reservoirs in long well sections, the research is applicable to the acidification of high-permeability heterogeneous sandstone reservoirs. A new technology of acidification for construction is an urgent task