Water-soluble temporary plugging agent for temporary blocking diversion in well fracturing, and preparation method thereof

Abstract

The invention discloses a water-soluble temporary plugging agent for temporary blocking diversion in well fracturing. The temporary plugging agent comprises unsaturated organic acid, sodium methallylsulfonate, N-vinylpyrrolidone, polyoxyethylene acrylate, an initiator, sodium hydroxide, a nano-modifier and distilled water. A preparation method of the temporary plugging agent comprises the following steps: adding distilled water into a reaction container, and introducing nitrogen to replace air; adding the unsaturated organic acid, sodium methallyl sulfonate and N-vinylpyrrolidone into the reaction container, stirring the added substances, adding 1 / 2 of the initiator, heating the obtained mixture to 100-110 DEG C, performing a reaction for 30 min, and adding sodium hydroxide; and heating the obtained reaction solution to 145-155 DEG C, performing a reaction for 1.0 h, adding the polyoxyethylene acrylate and the remaining initiator, heating the reaction solution to 175-185 DEG C, addingthe remaining initiator, performing a reaction for 2 h, adding the modifier, and drying the obtained reaction product to obtain the product. The temporary plugging agent has a good temporary blockingdiversion effect, has small damages to stratum after being degraded, passes compressive experiments, and has a compressive strength reaching 80 MPa or more.

Description

technical field [0001] The invention belongs to the technical field of increasing production of oil and natural gas, and in particular relates to a water-soluble high-strength temporary plugging agent for oil and gas well fracturing temporary plugging diversion and a preparation method thereof. Background technique [0002] my country's low-permeability oilfields are rich in petroleum geological reserves, and their resources account for about 30% of the country's total petroleum resources. Among the proven reserves, low-permeability oil reservoirs account for more than two-thirds of the country's reserves, and the development potential is huge. Although most low-permeability reservoirs have a large increase in production after fracturing, the production is still not high. In recent years, major oilfields have adopted multi-fracture technology or fracture diversion technology in the fracturing operation to intensify efforts to stimulate low-permeability reservoirs and maximiz...

AI Technical Summary

Problems solved by technology

In addition, the polymer mainly composed of polyacrylamide has also been used as a temporary plugging agent, and its plugging strength and temporary plugging rate can also meet the requirements of on-site construction, but its high viscosity after degradation makes fracturing difficult. The increase of liquid viscosity is not conducive to the flowback after construction, which will cause great damage to the formation

[0004] Therefore, the existing various temporary plugging agents have certain temporary plugging performance but also have their own defects. The release of inorganic salts during the dissolution process of the system composed of inorganic salts will cause permanent plugging of the formation, which is not conducive to later oil and gas production; Cross-linked polymers need to add a gel breaker after construction to break the gel. In construction operations that require a long temporary plugging time, the construction period will be increased, resulting in increased costs. At the same time, the solubility of cross-linked polymers is poor, and some in Fracturing fluid that cannot completely break the gel will also stay in the formation and affect the later mining process; the dissolution of PAM temporary plugging agent will increase the viscosity of the fracturing fluid, which is not conducive to the flowback of the fracturing fluid

Images